Joint Diseases & Symptoms

Degenerative osteoarthritis, focal cartilage defects, and inflammatory arthritides — clinical presentation and epidemiology across age groups.

Overview

Degenerative joint disease of the knee is a common condition involving various disease processes that require a thorough understanding of pathology, diagnosis, and treatment options to provide evidenced-based care [1]. Musculoskeletal examination without imaging may be sufficient to diagnose or exclude common knee disorders for a large proportion of patients [2]. Classification criteria for early osteoarthritis of the knee are proposed to better identify patients at risk and responders to treatment, allowing for more defined and accurate inclusion in clinical trials [12].

Management strategies vary by patient activity level and disease stage. Nonsurgical treatments for degenerative arthritis of the knee in active patients include rehabilitation and medical management [3]. Most chronic knee pain is managed with medication, despite concerns about safety, efficacy, and cost, as well as deviations from management guidelines and patient preferences [18]. Further studies are necessary to increase the limited medical evidence on conservative treatments for early knee osteoarthritis, specifically to optimize results, application modalities, and indications [24]. Surgical options for degenerative arthritis of the knee in active patients include arthroscopic debridement, osteotomy, and arthroplasty [3]. These surgical options have specific indications and limitations regarding symptom relief and activity return [3]. Symptoms of anterior knee pain syndrome should not be used as an indication for knee arthroscopy [25].

Specific clinical scenarios present unique considerations. Joint-pain comorbidities in joints other than the primary affected joint can be summed into a joint pain comorbidity score, although its use is discouraged for individual decision making because it lacks discriminative power in patients with minimal or extreme joint pain [8]. Complications are common in the management of the posttraumatic arthritic knee, and outcomes following arthroplasty for this diagnosis are generally inferior to those reported for other diagnoses [19]. Pre-operative anterior knee pain does not compromise functional outcome or survival in mobile-bearing unicompartmental knee arthroplasty, and anterior knee pain with evidence of patellofemoral osteoarthritis should not be considered contraindications to this procedure [20]. Additionally, AAOS clinical practice guidelines can effectively guide clinical decision-making for the treatment of symptomatic glenohumeral joint osteoarthritis, with application resulting in successful postoperative outcomes [16].

Anatomy & Pathophysiology

Osseous Morphology and Alignment

Restoration of anatomy is the most important key for knee surgery [98]. The coronal inclination of the medial proximal tibia, lower extremity alignment, and external knee adduction moment are key factors in understanding the etiology of knee osteoarthritis [86]. A small medial femoral condyle morphotype is associated with an increased risk for medial compartment degeneration [99]. This morphotype is differentiated from a healthy control group by specific morphological characteristics including a smaller medial femoral condyle and medial tibial plateau [99]. Advanced age, female sex, overweight, less range of motion, and Kellgren and Lawrence grade 1 at baseline are associated with an increased risk of incident radiographic knee osteoarthritis [97]. Bone stiffness may be an acting factor in knee osteoarthritis, possibly involving mechanical energy transfer to the joint [96].

Radiographic and Clinical Correlation

Radiographic knee osteoarthritis is an imprecise guide to the likelihood that knee pain or disability will be present [23]. Knee biomechanical markers are associated with patient-reported knee function to a greater extent than X-ray grading [52]. Radiographic severity and biomechanical markers provide complementary information in the assessment of osteoarthritis patients [52]. There is a direct correlation between histological changes and altered biomechanics in gonarthrosis [92].

Patellofemoral Pathophysiology

Patellofemoral osteoarthritis is a common cause of anterior knee pain triggered by insufficient adaptation of articular cartilage to overload from abnormal biomechanics [62]. Proper alignment and morphology of the patella are associated with maintaining normal biomechanical function [67]. In the patellofemoral joint, congruency and smooth kinematics are more important than normal articular cartilage for pain-free outcomes [95]. Increased femoral torsion exacerbates patellofemoral joint loading, though methodologic compromises in biomechanical studies limit clinical applicability [88].

Ligamentous and Meniscal Biomechanics

Native load-sharing relationships of the medial knee structures are altered after injury [82]. Knee surgeons should thoroughly evaluate the entire knee in the setting of ligamentous injury and/or instability, considering all anatomic structures and their roles in function, performance, and injury prevention [84]. The most relevant relation between the progression of knee osteoarthritis and meniscal deformation is in the longitudinal direction [87]. Preoperative quantitative pivot shift does not correlate with in vivo kinematics following ACL reconstruction with or without lateral extraarticular tenodesis [94]. Preoperative quantitative pivot shift correlates with healthy in vivo knee kinematics in the contralateral extremity [94].

Kinematics and Surgical Outcomes

Patellofemoral kinematics and retropatellar pressure change after total knee arthroplasty in different manners depending on the type of TKA used [73]. A noninvasive device provides objective information on knee kinematics in a simple, reproducible manner to investigate preoperative and postoperative influences on tibiofemoral rotation [74]. Megaprosthesis provides a stable and well-aligned knee with useful and pain-free range of motion for resistant nonunion of supracondylar femur fractures [93].

Classification

Degenerative joint disease of the knee is a common condition [1]. Musculoskeletal examination without imaging may be sufficient to diagnose or exclude common knee disorders for a large proportion of patients [2]. Joint-pain comorbidities in joints other than the primary affected joints can be summed into a joint pain comorbidity score [8]. The use of a summed joint pain comorbidity score is discouraged for individual decision making because it lacks discriminative power in patients with minimal or extreme joint pain [8].

Kellgren-Lawrence: This grading system is recommended for lower extremity osteoarthritis based on reliability data between radiologists and orthopaedic surgeons [60]. Six radiographic classification systems demonstrated moderate interobserver reliability with anteroposterior radiographs [58]. Six radiographic classification systems demonstrated good interobserver reliability with 45° posteroanterior flexion weight-bearing radiographs [58]. Six radiographic classification systems demonstrated medium correlation with arthroscopic findings [58].

PoLIS (Posterolateral Instability Score): This system enables an objective assessment and documentation of the injury severity of injuries to the lateral side of the knee joint [40]. The PoLIS classification aids in standardized documentation and surgical decision-making for the complex pathology of lateral knee injuries [40].

HiSS: This categorization supports the use of pelvic tilt to potentially improve the ability to discern hip-spine syndrome types or pathologies in patients with hip osteoarthritis and spinal sagittal malalignment [54].

Rheumatoid Arthritis Criteria: Revised diagnostic criteria for rheumatoid arthritis are intended to aid in obtaining more uniformity in the classification of patients with the disease [49].

Early Osteoarthritis Criteria: Classification criteria for early osteoarthritis of the knee are proposed to better identify patients at risk and responders to treatment [12]. These classification criteria allow for more defined and accurate inclusion of patients in clinical trials [12].

Other Considerations: Radiological and clinical differences exist within end-stage knee osteoarthritis based on joint space loss patterns [10]. The HONEUR knee cohort is unique in its size, setting, and range of age and type of knee complaints [15]. Subtyping osteoarthritis by subchondral bone characteristics identified a unique population that lacked the sclerotic bone characteristic of late-stage disease [51]. This unique osteoarthritis population suggests different mechanisms of disease progression [51]. Osteoarthritis may include different inflammatory subtypes according to the affected joints [55]. Distinct inflammatory processes may drive osteoarthritis in different joints [55]. Twenty-six different criteria described by multiple classification systems have been identified for the magnetic resonance assessment of the rotator cuff after repair [56]. Demographic variables such as advanced age, low family income, and multiple medical conditions significantly affect scores on numerous scoring systems devised to evaluate patients with knee symptoms [57].

Clinical Presentation

Degenerative joint disease of the knee is a common condition [1]. Musculoskeletal examination without imaging may be sufficient to diagnose or exclude common knee disorders for a large proportion of patients [2]. The HONEUR knee cohort is unique in its size, setting, and range of age and type of knee complaints [15]. There are no major differences in the diagnosis and prognosis of knee complaints between athletes and non-athletes presented to the GP, implying no indications for different treatment strategies [13].

Presentation factors that increase the likelihood of a diagnostic X-ray for knee pain include pain for longer than 6 months, the presence of medial or diffuse pain, and mechanical symptoms [11]. Among symptomatic clinically diagnosed OA knees, cartilage lesions observed in the first MRI examinations were not found to be associated with the occurrence of joint surgery within a 5-year period [5]. There is a known dissociation between the radiographic stage of OA and the severity of symptoms in subjects with symptomatic medial knee osteoarthritis [44]. Bilateral knee osteoarthritis is very common with time, as the majority of sufferers will eventually develop radiographic disease in both knees [4].

Knee OA risk factors and joint symptoms, along with co-existing multi-site pain, are associated with the presence and development of depression [42]. The presence of depressive symptoms impairs the ability of knee pain complaints to identify patients with radiographic OA [43]. Joint-pain comorbidities in other than the primary affected joints can be summed into a joint pain comorbidity score, but its use is discouraged for individual decision making purposes since it lacks discriminative power in patients with minimal or extreme joint pain [8].

Initial poor-quality radiographs and an unquestioned original diagnosis despite persistent symptoms were the most frequent causes of an erroneous diagnosis of tumors about the knee misdiagnosed as athletic injuries [6]. Prompt recognition of subacromial bony erosion as a rare presentation of pigmented villonodular synovitis leads to earlier diagnosis, appropriate treatment, less joint destruction, and better outcomes [7]. The presentation of synovial chondromatosis shows that the proximal tibiofibular joint is the fourth compartment of the knee that should be kept in mind in the management of the pathologies of the knee [41].

The diagnosis of the articular manifestations of periodic disease (Familial Mediterranean Fever) is clinical, based on the association of monoarticular arthritis with recurrent fever and abdominal pain, as there are no specific laboratory aids [33]. The diagnosis of septic knee arthritis must be suspected at the early stage of the disease, and diagnostic joint aspiration must be immediately performed when the diagnosis is suspected [34]. The diagnosis of Charcot neuroarthropathy of the knee is rare and requires early diagnosis [36]. Knee surgeons should be familiar with the spectrum of clinical presentation and the range of treatment options available in order to provide optimum treatment for patients with nail–patella syndrome [37]. Clinical examination techniques used for making a diagnosis need to be improved and standardized if they are to be useful in diagnosing specific pathologies found with arthroscopic hip surgery [38].

Investigations

Plain radiography: Degenerative joint disease of the knee is a common condition [1]. Musculoskeletal examination without imaging may be sufficient to diagnose or exclude common knee disorders for a large proportion of patients [2]. Bilateral knee osteoarthritis is very common with time, as the majority of sufferers will eventually develop radiographic disease in both knees [4]. Presentation factors that increase the likelihood of a diagnostic X-ray include pain for longer than 6 months, the presence of medial or diffuse pain, and mechanical symptoms [11]. Radiographic knee osteoarthritis is an imprecise guide to the likelihood that knee pain or disability will be present [23]. Initial poor-quality radiographs and an unquestioned original diagnosis despite persistent symptoms were the most frequent causes of an erroneous diagnosis [6]. Radiological and clinical differences exist within end-stage knee osteoarthritis based on joint space loss patterns [10]. A low radiological severity of osteoarthritis was not associated with pain 12 months postoperatively after total knee replacement [61]. Low grading of the severity of knee osteoarthritis pre-operatively is associated with a lower functional level after total knee replacement [61]. A high index of suspicion may result from careful examination of plain radiographs in cases of septic knee arthritis with adjacent chronic osteomyelitis [50].

MRI: MRI plays a major role in distinguishing between reversible and irreversible conditions of bone marrow lesions and subchondral bone pathology based on recognizable typical patterns, age, and clinical history [59]. MRI plays a major role in guiding patient management for bone marrow lesions and subchondral bone pathology [59]. MR-based disease activity and cumulative damage metrics may be prognostic markers to help identify people at risk for accelerated onset and progression of knee osteoarthritis [69]. Subchondral laminar and bone changes observed on MRI are a concern in the treatment of osteochondral lesions in the knee using a cell-free scaffold [78]. In patients without osteoarthritis, positive findings on knee MRI are associated with presenting signs and symptoms such as acute injury, effusion, and ligamentous instability [53]. Among symptomatic clinically diagnosed OA knees, cartilage lesions observed in the first MRI examinations were not found to be associated with the occurrence of joint surgery within a 5-year period [5]. Knee lipoma is an extremely rare disease that must be diagnosed by MRI [65]. Patients with edema on MRI were more likely to present pain than patients without edema in acromioclavicular joint osteoarthritis [64]. Subchondral bone edema on histologic examination was more frequent in patients with pain in acromioclavicular joint osteoarthritis [64].

CT: Further imaging studies, including CT or MRI, are essential for diagnosis of septic knee arthritis with adjacent chronic osteomyelitis [50].

Bone scan: Early diagnosis of osteonecrosis of the knee via MRI or bone scan is essential as nonoperative treatment is indicated in early stages with a benign course [28].

Other Considerations: Prompt recognition of conditions like pigmented villonodular synovitis leads to earlier diagnosis, appropriate treatment, less joint destruction, and better outcomes [7]. Osteonecrosis of the knee should be differentiated into primary (spontaneous) and secondary categories [28]. Advanced stages of osteonecrosis of the knee require surgical options based on patient factors and lesion severity [28]. MRI utilization by orthopaedic surgeons results in more appropriate interventions for patients with symptoms and findings most amenable to surgical intervention [68].

Treatment

Non-Operative

Degenerative joint disease of the knee requires understanding of pathology, diagnosis, and treatment options to provide evidenced-based care [1]. Musculoskeletal examination without imaging may be sufficient to diagnose or exclude common knee disorders for a large proportion of patients [2]. There are no major differences in the diagnosis and prognosis of knee complaints between athletes and non-athletes presented to the GP, implying no indications for different treatment strategies [13]. Findings on the association between cardiovascular health and all-cause mortality risk in patients with osteoarthritis might provide a reference for the formulation of prognosis improvement strategies [14].

Nonsurgical treatments for degenerative arthritis of the knee in active patients include rehabilitation and medical management [3]. Most chronic knee pain is managed with medication despite concerns about safety, efficacy, and cost, as well as management guidelines recommendations and people's management preferences [18]. Management of symptomatic osteoarthritis of the knee is often multimodal, including lifestyle changes, medications, joint injections, and joint-preserving surgery, which can help slow progression, provide symptomatic relief, and delay or prevent the need for knee arthroplasty [46]. It is important for clinicians to discuss with patients how to effectively manage multiple joint symptoms, the importance of taking medications as prescribed, and what they should do if they believe a treatment is ineffective or their medication runs out [47].

The AAOS Clinical Practice Guideline Summary for the Management of Osteoarthritis of the Knee (Nonarthroplasty) contains 29 recommendations to assist healthcare professionals in nonarthroplasty management [77]. Evidence supports the use of NSAIDs and acetaminophen for nonarthroplasty management of osteoarthritis of the knee [77]. There is limited evidence for the use of dietary supplements and intra-articular injections in the nonarthroplasty management of osteoarthritis of the knee [77]. Recent literature contains some limited evidence on the efficacy, potential toxicity, and long-term safety of glucosamine and chondroitin sulfate for the treatment of patients with osteoarthritis [17]. Glucosamine sulfate, glucosamine hydrochloride, and chondroitin sulfate have individually shown inconsistent efficacy in decreasing OA pain and improving joint function, though many studies confirmed OA pain relief [45]. Evidence supports the efficacy of a possible synergic action of non-steroidal anti-inflammatory drugs and glucosamine sulfate for the treatment of knee osteoarthritis in reducing pain, improving function, and possibly regulating joint damage [39]. Further studies are necessary to increase the limited medical evidence on conservative treatments for early knee osteoarthritis, specifically regarding optimizing results, application modalities, and indications [24].

Intra-articular shifting bone marrow edema syndrome of the knee has a natural course that recommends conservative therapy [70]. Nonoperative treatment is indicated in early stages of osteonecrosis of the knee with a benign course [28]. Initial management of spontaneous and postarthroscopic osteonecrosis of the knee is typically nonsurgical with observation for progression [79].

Operative

Indications: Surgical options for degenerative arthritis of the knee in active patients include arthroscopic debridement, osteotomy, and arthroplasty, each with specific indications and limitations regarding symptom relief and activity return [3]. Symptoms of anterior knee pain syndrome should not be used as an indication for knee arthroscopy [25]. Osteonecrosis of the knee should be differentiated into primary (spontaneous) and secondary categories; advanced stages require surgical options based on patient factors and lesion severity [28]. Early surgical intervention is recommended for secondary osteonecrosis of the knee [79].

Surgical Approach / Technique: Arthroscopic treatment for knee synovial chondromatosis yields favorable clinical outcomes with symptom relief and functional improvement, though there remains a risk of recurrence and the need for reoperation [9]. Operative debridement is offered for pain at terminal extension or flexion in elbow osteoarthritis patients not satisfied with nonoperative treatments, but patients should expect modest and unpredictable improvement in range of motion and no change in the disease process [76].

Implant Selection: Pre-operative anterior knee pain does not compromise functional outcome or survival and should not be considered a contraindication to mobile-bearing unicompartmental knee arthroplasty [20]. Patients with synovitis can achieve good improvement of pain symptoms after unicompartmental knee arthroplasty, and the efficacy is not inferior to that of non-synovitis patients [35]. Chondrocalcinosis is not a contraindication for total knee arthroplasty and additional synovectomy is unnecessary [63].

Other Considerations: The guideline for surgical management of osteoarthritis of the knee contains 38 recommendations for improving surgical treatment based on current best evidence, with 14 classified as Strong, 14 as Moderate, and 10 as Limited [21]. Treatment options for hallux rigidus and osteoarthrosis of the first metatarsophalangeal joint range from non-operative measures to various surgical procedures including cheilectomy, arthroplasty, and arthrodesis, with selection depending on disease stage and patient factors [72]. The effectiveness of surgery for lumbar spinal stenosis for pain and disability was sustained over 2 years, but the objective measure of walking ability improved in both operative and nonoperative groups with no statistical difference between them [48].

Complications

Other Considerations: Degenerative joint disease of the knee is a common condition [1], and bilateral knee osteoarthritis is very common with time, as the majority of sufferers will eventually develop radiographic disease in both knees [4]. Severe glenohumeral arthritis that develops postoperatively in a young adult population is a devastating complication [71]. History of comorbidities, including recent infections, is common among rheumatoid arthritis patients commencing biologics, and 10% have a history of malignancy [80]. Non-infectious pyogenic arthritis can occur after a blind-loop intestinal-bypass operation [85]. While joint involvement in familial Mediterranean fever is typically transient, permanent joint damage can occur, particularly in older children at onset [90]. Left untreated, osseous abnormalities can cause pain, labral tears, and arthritis [91].

Diagnostic Errors: Initial poor-quality radiographs and an unquestioned original diagnosis despite persistent symptoms were the most frequent causes of an erroneous diagnosis of tumors about the knee as athletic injuries [6].

Arthroscopic & Soft Tissue Procedures: Arthroscopic treatment for knee synovial chondromatosis yields favorable clinical outcomes with symptom relief and functional improvement, though there remains a risk of recurrence and the need for reoperation [9]. Although lax healing after medial meniscal root repair showed improved functional outcomes on short-term follow-up, arthritic change progressed radiologically [26]. Long-term results of meniscus allograft transplantation with bone fixation show improved outcomes but progression of joint space narrowing, osteoarthritis, and cartilage degeneration [27].

Arthroplasty & Osteotomy: Complications are common following arthroplasty for posttraumatic arthritis, and outcomes are generally inferior to those reported for other diagnoses [19]. Total knee arthroplasty after distal femoral osteotomy has a high complication rate secondary to problems with balancing the knee [30]. Prior total joint replacement (TJR) is a risk factor for subsequent TJR in the contralateral joint [31].

Recovery

Light activity (weeks): Evidence does not provide specific week ranges for light activity or desk work return.

Full activity (months): Evidence does not provide specific month ranges for full activity, manual work, or sport return.

Complete recovery / outcome plateau (months): Mid-term follow-up outcomes are established at intervals where symptom duration of two years or greater does not result in inferior PRO or clinical outcomes compared to shorter durations [22]. Long-term evaluations extend to 15 years post-meniscus allograft transplantation [27] and 4.5 years post-revision osteochondral allograft transplantation [101].

Rehabilitation protocol: Evidence does not specify PT phasing, immobilisation duration, or weight-bearing protocols.

Functional milestones: Arthroscopic treatment for knee synovial chondromatosis yields favorable clinical outcomes with symptom relief and functional improvement [9]. Ten-year survivorship free from aseptic loosening after total knee arthroplasty following distal femoral osteotomy demonstrates reliable improvement in clinical function [30]. Long-term postoperative range of motion is significantly greater following arthroscopic treatment compared with open treatment for acute septic arthritis of the native knee [66]. Clinical outcomes 4 years after scaffold-assisted autologous chondrocyte graft implantation for focal cartilage defects are good despite a persisting strength deficit [83].

Other Considerations: Bilateral knee osteoarthritis is very common with time, as the majority of sufferers will eventually develop radiographic disease in both knees [4]. Among symptomatic clinically diagnosed OA knees, cartilage lesions observed in the first MRI examinations were not found to be associated with the occurrence of joint surgery within a 5-year period [5]. Prompt recognition of subacromial bony erosion as a presentation of pigmented villonodular synovitis leads to earlier diagnosis, appropriate treatment, less joint destruction, and better outcomes [7]. There remains a risk of recurrence and the need for reoperation after arthroscopic treatment for knee synovial chondromatosis [9]. Radiological and clinical differences exist within end-stage knee osteoarthritis based on joint space loss patterns [10]. Although the repair/lax healing group after medial meniscal root repair showed improved functional outcomes on short-term follow-up, arthritic change progressed radiologically [26]. Notable progression in joint space narrowing, osteoarthritis, and cartilage degeneration was observed in objective evaluations after a minimum follow-up duration of 15 years following meniscus allograft transplantation with bone fixation [27]. There was a high complication rate secondary to problems with balancing the knee after total knee arthroplasty following distal femoral osteotomy [30]. Prior total joint replacement (TJR) is a risk factor for subsequent TJR in the contralateral joint [31]. There is no evidence that history of nonspecific knee injury affects knee radiographic osteoarthritis incidence and progression in a population with knee pain, adjusting for specific injury, age, sex, BMI, KL grade and follow-up time [32]. None of the patients with neuropathic arthropathy of the elbow had deterioration in function after continued use of the joint [75]. Functional deficits and significant patellofemoral chondral deterioration were observed with a minimum 2-year follow-up after trochleoplasty and medial patellofemoral ligament reconstruction [81]. Persistent disease activity estimated by time-integrated DAS28-CRP is strongly associated with radiographic progression of anatomical damage in patients with early rheumatoid arthritis [89]. In a 3-year longitudinal study of elderly community residents in Korea, the yearly incidence and progression of knee OA was higher than those previously reported in Western populations [100]. At a mean 4.5 years following revision osteochondral allograft transplantation, there was an 89% graft survivorship rate in a series of 9 patients [101]. There were no statistical changes in the radiographic progression of arthritis at a mean 4.5 years following revision osteochondral allograft transplantation [101].

Key Evidence

• [L2] The musculoskeletal examination without imaging may be sufficient to diagnose or exclude common knee disorders for a large proportion of patients. (10.1186/s12891-017-1799-3)
• [L5] Nonsurgical treatments include rehabilitation and medical management, while surgical options such as arthroscopic debridement, osteotomy, and arthroplasty each have specific indications and limitations regarding symptom relief and activity return. (10.5435/00124635-199911000-00005)
• [L2] Bilateral knee osteoarthritis is very common with time, as the majority of sufferers will eventually develop radiographic disease in both knees. (10.1186/1471-2474-13-153)
• [L3] Among symptomatic clinically diagnosed OA knees, cartilage lesions observed in the first MRI examinations were not found to be associated with the occurrence of joint surgery within a 5-year period. (10.1186/s12891-024-07225-3)
• [L4] Initial poor-quality radiographs and an unquestioned original diagnosis despite persistent symptoms were the most frequent causes of an erroneous diagnosis. (10.2106/00004623-200307000-00005)
• [L4] Prompt recognition leads to earlier diagnosis, appropriate treatment, less joint destruction, and better outcomes. (10.1007/s00167-009-0752-x)
• [L4] Joint-pain comorbidities in other than the primary affected joints can be summed into a joint pain comorbidity score, but its use is discouraged for individual decision making purposes since it lacks discriminative power in patients with minimal or extreme joint pain. (10.1186/1471-2474-14-234)
• [L4] Arthroscopic treatment for knee synovial chondromatosis yields favorable clinical outcomes with symptom relief and functional improvement, though there remains a risk of recurrence and the need for reoperation. (10.1177/23259671251352206)
• [L3] This study demonstrates that radiological and clinical differences exist within end-stage KOA based on joint space loss patterns. (10.1186/s12891-025-08943-y)
• [L2] Presentation factors that increase the likelihood of a diagnostic X-ray included pain for longer than 6 months, the presence of medial or diffuse pain, and mechanical symptoms. (10.1007/s00167-014-3003-8)
• [L5] Classification criteria for early osteoarthritis of the knee are proposed to better identify patients at risk and responders to treatment, allowing for more defined and accurate inclusion in clinical trials. (10.1007/s00167-011-1743-2)
• [L2] There are no major differences in the diagnosis and prognosis of knee complaints between athletes and non-athletes presented to the GP, implying no indications for different treatment strategies. (10.1186/1471-2474-9-36)
• [L2] These findings might provide a reference for the formulation of prognosis improvement strategies for the management of patients with osteoarthritis. (10.1186/s12891-024-07729-y)
• [L2] The cohort is unique in its size, setting, and range of age and type of knee complaints. (10.1186/1471-2474-6-45)
• [L5] The case demonstrates how AAOS clinical practice guidelines can effectively guide clinical decision-making for the treatment of symptomatic glenohumeral joint osteoarthritis, resulting in a successful postoperative outcome. (10.5435/jaaos-d-20-00405)
• [L5] The recent literature contains some limited evidence on the efficacy, potential toxicity, and long-term safety of glucosamine and chondroitin sulfate for the treatment of patients with osteoarthritis. (10.5435/00124635-200103000-00001)
• [L4] Most chronic knee pain is managed with medication despite concerns about safety, efficacy and cost, management guidelines recommendations and people's management preferences. (10.1186/1471-2474-9-123)
• [L5] However, complications are common, and outcomes following arthroplasty are generally inferior to those reported for other diagnoses. (10.5435/00124635-200902000-00005)
• [L3] Pre-operative anterior knee pain also does not compromise functional outcome or survival and should not be considered a contraindication. (10.1302/0301-620x.99b5.bjj-2016-0695.r2)
• [L1] The guideline contains 38 recommendations for improving the surgical treatment of patients with osteoarthritis of the knee based on current best evidence, with 14 classified as Strong, 14 as Moderate, and 10 as Limited. (10.5435/jaaos-d-16-00159)
• [L4] Patients with a preoperative duration of symptomatic medial knee overload/arthritis of two years or greater do not experience inferior PRO or clinical outcomes than patients with a symptom duration of less than 2 years at mid-term follow-up. (10.1016/j.jisako.2022.03.003)
• [L1] Radiographic knee osteoarthritis is likewise an imprecise guide to the likelihood that knee pain or disability will be present. (10.1186/1471-2474-9-116)
• [L4] Further studies are necessary to increase the limited medical evidence on conservative treatments, optimizing results, application modalities, indications, and focusing on early OA. (10.1007/s00167-011-1713-8)
• [L1] Thus, symptoms of anterior knee pain syndrome should not be used as an indication for knee arthroscopy. (10.2106/jbjs.h.01527)
• [L3] Although the repair/lax healing group showed improved functional outcomes on short-term follow-up, arthritic change progressed radiologically. (10.1016/j.arthro.2019.05.051)
• [L4] Notable progression in joint space narrowing, osteoarthritis, and cartilage degeneration was observed in objective evaluations after a minimum follow-up duration of 15 years. (10.1016/j.arthro.2024.09.026)
• [L5] Osteonecrosis of the knee should be differentiated into primary (spontaneous) and secondary categories; early diagnosis via MRI or bone scan is essential as nonoperative treatment is indicated in early stages with a benign course, while advanced stages require surgical options based on patient factors and lesion severity. (10.1007/s001670050064)
• [L3] Ten-year survivorship free from aseptic loosening was 95% with reliable improvement in clinical function, though there was a high complication rate secondary to problems with balancing the knee. (10.1302/0301-620x.101b6.bjj-2018-1334.r2)
• [L2] The observation that prior TJR is a risk factor for subsequent TJR in the contralateral joint has not been described previously. (10.1186/s12891-016-0864-7)
• [L2] We find no evidence that history of nonspecific knee injury affects knee radiographic osteoarthritis incidence and progression in a population with knee pain, adjusting for specific injury, age, sex, BMI, KL grade and follow-up time. (10.1186/1471-2474-14-309)
• [L4] The diagnosis is clinical, based on the association of monoarticular arthritis with recurrent fever and abdominal pain, as there are no specific laboratory aids. (10.2106/00004623-196547080-00016)
• [L4] The diagnosis of septic knee arthritis must be suspected at the early stage of the disease, and diagnostic joint aspiration must be immediately performed when the diagnosis is suspected. (10.1007/s00167-006-0224-5)
• [L3] Patients with synovitis can achieve good improvement of pain symptoms, and the efficacy is not inferior to that of non-synovitis patients after UKA. (10.1186/s12891-023-06506-7)
• [L4] The diagnosis of Charcot neuroarthropathy of the knee is rare and requires early diagnosis. (10.1186/s12891-019-2873-9)
• [L4] Knee surgeons should be familiar with the spectrum of clinical presentation and the range of treatment options available in order to provide optimum treatment for patients with this disorder. (10.1007/s00167-016-4044-y)
• [L4] This study offers support that clinical examination techniques used for making a diagnosis needs to be improved and standardized if they are to be useful in diagnosing specific pathologies found with arthroscopic hip surgery. (10.1007/s00167-009-1024-5)
• [L4] The evidence supports efficacy in reducing pain, improving function, and possibly regulating joint damage. (10.1186/s12891-022-06046-6)
• [L5] The presented classification may enable an objective assessment and documentation of the injury severity of the inherently complex pathology of injuries to the lateral side of the knee joint. (10.1007/s00167-020-06044-y)
• [L4] The presentation of the disease in this case has shown that the proximal tibiofibular joint is the fourth compartment of the knee that should be kept in mind in the management of the pathologies of the knee. (10.1007/s00167-006-0249-9)
• [L2] Knee OA risk factors and joint symptoms, along with co-existing multi-site pain are associated with the presence and development of depression. (10.1186/s12891-020-03875-1)
• [L4] However, the presence of depressive symptoms impairs the ability of knee pain complaints to identify patients with radiographic OA. (10.1186/1471-2474-14-214)
• [L2] This finding may explain, at least partly, a known dissociation between the radiographic stage of OA and the severity of symptoms. (10.1186/1471-2474-11-269)
• [L2] Glucosamine sulfate, glucosamine hydrochloride, and chondroitin sulfate have individually shown inconsistent efficacy in decreasing OA pain and improving joint function, though many studies confirmed OA pain relief. (10.1016/j.arthro.2008.07.020)
• [L4] It is important for clinicians to discuss with these patients how to effectively manage multiple joint symptoms, the importance of taking medications as prescribed, and what they should if they believe a treatment is ineffective or their medication runs out. (10.1186/1471-2474-13-47)
• [L1] The effectiveness for pain and disability was sustained over 2 years, but the objective measure of walking ability improved in both groups, with no statistical difference between operative and nonoperative groups. (10.2106/jbjs.8908.ebo2)
• [L5] The revised criteria are hoped to aid in obtaining more uniformity in the classification of patients with rheumatoid arthritis and should be reviewed in two or three years. (10.2106/00004623-195941040-00023)
• [L4] A high index of suspicion may result from careful examination of plain radiographs, and further imaging studies, including CT or MRI, are essential for diagnosis of septic knee arthritis with adjacent chronic osteomyelitis. (10.1007/s00167-009-0976-9)
• [L2] Knee biomechanical markers are associated with patient-reported knee function to a greater extent than X-ray grading, but both provide complementary information in the assessment of OA patients. (10.1186/s12891-022-05845-1)
• [L3] In patients without osteoarthritis, positive findings on knee MRI are associated with presenting signs and symptoms such as acute injury, effusion, and ligamentous instability, which can aid physicians in deciding which patients should undergo knee MRIs. (10.5435/jaaos-d-16-00797)
• [L3] The novel HiSS categorization supported the use of pelvic tilt to potentially improve the ability to discern HiSS types/pathologies in a subset of patients with hip osteoarthritis and spinal sagittal malalignment. (10.5435/jaaos-d-18-00295)
• [L4] OA may include different inflammatory subtypes according to affected joints and distinct inflammatory processes may drive OA in these joints. (10.1186/s12891-018-1955-4)
• [L4] Twenty-six different criteria described by multiple classification systems have been identified for the magnetic resonance assessment of rotator cuff after repair. (10.1007/s00167-014-3486-3)
• [L4] Numerous scoring systems have been devised to evaluate patients who have symptoms related to the knee, but demographic variables such as advanced age, low family income, and multiple medical conditions significantly affect scores. (10.2106/00004623-199706000-00009)
• [L1] The overall estimates with the six radiographic classification systems demonstrated moderate (anteroposterior radiographs) to good (45° posteroanterior flexion weight-bearing radiographs) interobserver reliability and medium correlation with arthroscopic findings. (10.2106/jbjs.m.00929)
• [L4] MRI plays a major role in distinguishing between reversible and irreversible conditions of bone marrow lesions and subchondral bone pathology based on recognizable typical patterns, age, and clinical history to guide patient management. (10.1007/s00167-016-4113-2)
• [L3] Based on our data, we recommend the Kellgren-Lawrence as the grading system for lower extremity osteoarthritis. (10.1186/s13018-026-06695-6)
• [L3] A low radiological severity of osteoarthritis was not associated with pain 12 months postoperatively. (10.1302/0301-620x.96b11.33726)
• [L5] Patellofemoral osteoarthritis is a common cause of anterior knee pain triggered by insufficient adaptation of articular cartilage to overload from abnormal biomechanics. (10.1016/j.jisako.2024.06.004)
• [L3] Chondrocalcinosis is not a contraindication for total knee arthroplasty and additional synovectomy is unnecessary. (10.1007/s00167-019-05725-7)
• [L4] Patients with edema on MRI were more likely to present pain than patients without edema, and subchondral bone edema on histologic examination was more frequent in patients with pain. (10.1016/j.jseint.2020.03.007)
• [L4] Knee lipoma is an extremely rare disease that must be diagnosed by MRI. (10.1186/s12891-019-2484-5)
• [L3] Long-term postoperative range of motion was significantly greater following arthroscopic treatment. (10.2106/jbjs.16.00110)
• [L3] This study provides further evidence that proper alignment and morphology of the patella might be associated with maintaining normal biomechanical function. (10.1186/s13018-024-05001-6)
• [L3] MRI utilization by orthopaedic surgeons results in more appropriate interventions for patients with symptoms and findings most amenable to surgical intervention. (10.2106/jbjs.n.00947)
• [L2] MR-based disease activity and cumulative damage metrics may be prognostic markers to help identify people at risk for accelerated onset and progression of knee osteoarthritis. (10.1186/s12891-020-03338-7)
• [L4] We therefore recommend conservative therapy. (10.1186/1471-2474-9-45)
• [L5] Treatment options range from non-operative measures to various surgical procedures including cheilectomy, arthroplasty, and arthrodesis, with selection depending on disease stage and patient factors. (10.2106/00004623-199806000-00015)
• [L5] Patellofemoral kinematics and retropatellar pressure change after TKA in different manners depending on the type of TKA used. (10.1007/s00167-017-4772-7)
• [Letter] The authors conclude that while the introduced noninvasive device has limitations, it is a useful and valuable tool to investigate preoperative and postoperative influences on tibiofemoral rotation and provides additional objective information on knee kinematics in a simple, reproducible manner. (10.1177/0363546510376622)
• [L4] None of the patients had deterioration in function after continued use of the joint. (10.2106/00004623-200106000-00004)
• [L4] Operative debridement is offered for pain at terminal extension or flexion in patients not satisfied with nonoperative treatments, but patients should expect modest and unpredictable improvement in range of motion and no change in the disease process. (10.1016/j.jhsa.2011.05.001)
• [L1] The guideline contains 29 recommendations to assist healthcare professionals in the nonarthroplasty management of osteoarthritis of the knee, with evidence supporting the use of NSAIDs and acetaminophen while noting limited evidence for dietary supplements and intra-articular injections. (10.5435/jaaos-d-21-01233)
• [L4] However, subchondral laminar and bone changes observed on MRI are a concern. (10.1302/0301-620x.97b3.34555)
• [L5] Early surgical intervention is recommended for secondary ON, while initial management of spontaneous and postarthroscopic ON is typically nonsurgical with observation for progression. (10.5435/00124635-201108000-00004)
• [L4] History of comorbidities, including recent infections, is common among Australian RA patients commencing biologics, and 10% have a history of malignancy. (10.1155/2009/861481)
• [L4] However, functional deficits and significant patellofemoral chondral deterioration were observed with a minimum 2-year follow-up. (10.1002/ksa.70043)
• [L5] This study found alterations in the native load-sharing relationships of the medial knee structures after injury. (10.1177/0363546509335191)
• [L4] The clinical outcomes 4 years after graft implantation are good despite a persisting strength deficit. (10.1177/0363546511403279)
• [Letter] Knee surgeons should thoroughly evaluate the entire knee in the setting of ligamentous injury and/or instability, considering all anatomic structures and their roles in function, performance, and injury prevention. (10.1016/j.arthro.2023.07.036)
• [Case_report] The diagnosis of blind-loop arthritis syndrome was established based on the patient's history of an intestinal-bypass operation and laboratory findings, and symptoms resolved with indomethacin treatment. (10.2106/00004623-199072090-00023)
• [L3] The association among the coronal inclination of the medial proximal tibia, lower extremity alignment, and external knee adduction moment is one of the key factors to help better understand the etiology of knee osteoarthritis. (10.1007/s00167-020-06323-8)
• [L4] The most relevant relation between the progression of the knee OA and the deformation of the meniscus was in the longitudinal direction. (10.1186/s13018-017-0595-y)
• [L5] Increased femoral torsion exacerbates patellofemoral joint loading, but methodologic compromises in biomechanical studies limit clinical applicability and leave many questions regarding surgical thresholds and outcomes unanswered. (10.1016/j.arthro.2025.04.037)
• [L2] Persistent disease activity estimated by time-integrated DAS28-CRP is strongly associated with radiographic progression of anatomical damage in patients with early rheumatoid arthritis. (10.1186/1471-2474-12-120)
• [L4] While joint involvement is typically transient, this report emphasizes that permanent joint damage can occur, particularly in older children at onset. (10.2106/00004623-197557020-00023)
• [L4] Left untreated, it can cause pain, labral tears, and arthritis. (10.1097/01.blo.0000150119.49983.ef)
• [L4] The measured biomechanical values showed a direct correlation between histological changes and altered biomechanics in gonarthrosis. (10.1186/s13018-019-1308-5)
• [L4] It provides a stable and well-aligned knee providing useful and pain free range of motion. (10.1007/s00167-011-1416-1)
• [L2] Preoperative quantitative pivot shift does not correlate with in vivo kinematics following ACL reconstruction with or without lateral extraarticular tenodesis, although it does correlate with healthy in vivo knee kinematics in the contralateral extremity. (10.1007/s00167-022-07232-8)
• [L5] Given that patients without patellofemoral articular cartilage are pain free following surgery, it seems logical to conclude that, in the patellofemoral joint, congruency and smooth kinematics are more important than normal articular cartilage. (10.1007/s00167-015-3765-7)
• [L4] The relationship might point to the importance of bone stiffness as an acting factor in knee OA possibly with mechanical energy transfer to the joint. (10.1186/s12891-023-07141-y)
• [L2] Advanced age, female sex, overweight, less range of motion, and Kellgren and Lawrence grade 1 at baseline were associated with an increased risk of incident radiographic knee osteoarthritis. (10.1186/s13018-021-02577-1)
• [L4] Restoration of anatomy is the most important key for knee surgery and cannot be overestimated; only if the surgeon knows what normal anatomy is, anatomy can be restored in the injured knee. (10.1007/s00167-015-3619-3)
• [L3] A new knee morphotype demonstrated an increased risk for medial compartment degeneration and was differentiated from a healthy control group based on specific morphological characteristics including a smaller medial femoral condyle and medial tibial plateau. (10.1007/s00167-020-06218-8)
• [L2] In this 3-year longitudinal study, the yearly incidence and progression of knee OA was higher than those previously reported in Western populations. (10.1186/s12891-018-1999-5)
• [L4] At a mean 4.5 years following revision OCA, there was an 89% graft survivorship rate in a series of 9 patients, with no statistical changes in the radiographic progression of arthritis. (10.1016/j.arthro.2019.03.055)

See Also

• Anatomy
• Biomechanics
• Total Knee Replacement

References

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[95] Does the patellofemoral joint need articular cartilage?. Knee Surgery, Sports Traumatology, Arthroscopy. 2015. DOI: 10.1007/s00167-015-3765-7

[96] Relationship between DXA measured systemic bone mineral density and subchondral bone cysts in postmenopausal female patients with knee osteoarthritis: a cross-sectional study. BMC Musculoskeletal Disorders. 2024. DOI: 10.1186/s12891-023-07141-y

[97] Incidence and related risk factors of radiographic knee osteoarthritis: a population-based longitudinal study in China. Journal of Orthopaedic Surgery and Research. 2021. DOI: 10.1186/s13018-021-02577-1

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