Lateral compartment osteoarthritis of the knee

Long-term functional success and robust implant survival in lateral unicompartmental knee arthroplasty: A case series with a mean follow-up of twenty two and a half years

PURPOSE

Lateral unicompartmental knee arthroplasty (UKA) is an accepted treatment option in cases of end-stage lateral osteoarthritis. While lateral UKA has many proposed advantages compared to total knee arthroplasty, its technical challenges and relatively small number of cases make this an uncommon procedure. The aim of this study was to report the survivorship and functional outcomes beyond 20 years of follow-up of isolated UKA.

METHODS

Between January 1988 and October 2003, 54 lateral UKAs were performed in a single center. The fitted prosthesis was a fixed plate and cemented polyethylene (PE). All patients had isolated lateral tibiofemoral osteoarthritis, including five open meniscectomies, three arthroscopies, and three open reductions of lateral tibial plateau fractures. Patients with a minimum of 20 years of follow-up were included in the final analysis.

RESULTS

Of the 54 UKA, 22 died before reaching the minimum follow-up period and four were lost to follow-up. Twenty-eight were included in the final analysis. Among them, 21 patients remained alive and an additional seven were deceased after 20 years. The mean age at the last follow-up was 84.8 ± 11.9 years with a mean follow-up duration of 22.5 ± 2.1 years. Of the 28 knees, eight underwent revision surgery (5 for the progression of osteoarthritis; 2 for aseptic loosening; 1 for PE wear). Kaplan-Meier survival analysis revealed a survival rate at 20 and 25 years of 72.3% (CI 59.1; 88.6). The average time to revision was 14.9 ± 4.9 years. At the last follow-up, the mean function Knee Society Score (KSS) was 41.5 ± 32.9 and the mean objective KSS score was 79.4 ± 9.7. In the unrevised population, 94.7% of patients (n = 18) reported being satisfied or very satisfied with the surgery.

CONCLUSION

Lateral UKA remains a viable treatment option for patients with isolated lateral tibiofemoral osteoarthritis, providing satisfactory 20-year implant survivorship and high patient satisfaction.

Robotic-arm-assisted lateral unicompartmental knee arthroplasty leads to high implant survival and patient satisfaction at mean 10-year follow-up

BACKGROUND

There is a lack of literature reporting on long-term outcomes following robotic-arm-assisted lateral unicompartmental knee arthroplasty (UKA). This study assessed the long-term survivorship, patient-reported satisfaction and pain scores following robotic-arm-assisted lateral UKA for lateral compartment osteoarthritis (OA).

METHODS

A single surgeon's database was reviewed to identify all patients who underwent robotic-arm-assisted lateral UKA with a cemented, fixed-bearing prosthesis prior to May 2015. Patients were contacted to determine implant survivorship, satisfaction and pain. Kaplan-Meier models were applied to analyse survival.

RESULTS

A total of 77 knees (70 patients) with a mean follow-up of 10.2 ± 1.5 years (range: 8.1-13.3) were included. Five knees were revised, corresponding to a 10-year survivorship of 96.1% and estimated survival time of 12.7 ± 0.3 years (95% confidence interval: 12.2-13.2) with all-cause revision as the endpoint. Unexplained pain (40.0%) and progression of OA (40.0%) in contralateral compartments were the most reported reasons for revision. Among patients without revision, 94.4% were either satisfied or very satisfied with their lateral UKA and the average pain score was 1.1.

CONCLUSION

Robotic-arm-assisted lateral UKA led to high implant survivorship and patient satisfaction, and low pain scores at long-term follow-up. Progression of OA in contralateral compartments and unexplained pain were the most frequent reasons for revision. These findings support the continued use of robotic-arm-assisted lateral UKA for lateral compartment OA; however, its clinical value over conventional techniques remains to be established in prospective comparative studies.

LEVEL OF EVIDENCE

Therapeutic Level IV.

Effect of Varus-Producing Distal Femoral Osteotomy and High Tibial Osteotomy on Compartment Pressures and Contact Area at Varying Degrees of Knee Flexion

Background

In patients with valgus alignment and degenerative changes in the lateral compartment, both distal femoral osteotomy (DFO) and high tibial osteotomy (HTO) can be used to unload the lateral compartment. Prior studies have shown that in valgus knees, the tibial wear is posterior and DFO exerts the greatest effect in extension; however, its effect is decreased as flexion angle rises.

Hypothesis

Medial closing-wedge (MCW) HTO would significantly decrease contact area, mean contact pressure (MCP), and peak contact pressure (PCP) in the lateral knee compartment through knee flexion to a greater extent compared with lateral opening-wedge (LOW) DFO.

Study Design

Controlled laboratory study.

Methods

MCWHTO and LOWDFO were performed, correcting a mean of 8° of valgus alignment, in 10 cadaveric knees using plate fixation. Tibiofemoral contact pressure of the medial and lateral compartments was measured in 0°, 30°, 60°, and 90° of knee flexion before and after osteotomy using thin electronic sensors and load applied through an Instron device. PCP, MCP, and contact area were measured for each condition.

Results

The lateral MCP was significantly decreased in the HTO state compared with the native state in 30° (P = .015), 60° (P = .0199), and 90° (P < .0001) of flexion. The lateral MCP was also significantly decreased in the HTO state when compared with the DFO state in 60° (P = .0093) and 90° of flexion (P < .0001). After DFO, the lateral MCP returned to that of the native state in 60° (P > .999) and 90° (P > .999) of flexion. The lateral PCP decreased for all test states in all degrees of flexion; the HTO state was significantly decreased when compared with the native state in 60° (P < .0001) and 90° (P < .0001).

Conclusion

With varus corrections of 8°, MCWHTO was more effective at unloading the lateral compartment than LOWDFO. This effect was significant as the knee flexion angle increased. This study should be considered as one aspect of the surgical decision-making process.

Clinical Relevance

In patients with mild to moderate valgus deformity without hypoplastic lateral femoral condyle and without significant joint line obliquity, MCWHTO may improve offloading of the lateral compartment in flexion.

Association of AI-determined Kellgren-Lawrence grade with medial meniscus extrusion and cartilage thickness by AI-based 3D MRI analysis in early knee osteoarthritis

The associations among Kellgren-Lawrence (KL) grade, medial meniscus extrusion (MME), and cartilage thickness in knee osteoarthritis (OA) remain insufficiently understood. Our aim was to determine these associations in early to moderate medial tibiofemoral knee OA. We included 469 subjects with no lateral OA from the Kanagawa Knee Study. KL grade was assessed using artificial intelligence (AI) software. The MME was measured by MRI, and the cartilage thickness was evaluated in 18 subregions of the medial femorotibial joint by another AI system. The median MME width was 1.4 mm in KL0, 1.5 mm in KL1, 2.4 mm in KL2, and 6.0 mm in KL3. Cartilage thinning in the medial femur occurred in the anterior central subregion in KL1, expanded inwardly in KL2, and further expanded in KL3. Cartilage thinning in the medial tibia occurred in the anterior and middle external subregions in KL1, expanded into the anterior and middle central subregions in KL2, and further expanded in KL3. The absolute correlation coefficient between MME width and cartilage thickness increased as the KL grade increased in some subregions. This study provides novel insights into the early stages of knee OA and potentially has implications for the development of early intervention strategies.

Gender-specific distribution of knee morphology according to CPAK and functional phenotype classification: analysis of 8739 osteoarthritic knees prior to total knee arthroplasty using artificial intelligence

PURPOSE

Osteoarthritis of the knee is commonly associated with malalignment of the lower limb. Recent classifications, as the Coronal Plane Alignment of the Knee (CPAK) and Functional Phenotype classification, describe the bony knee morphology in addition to the overall limb alignment. Data on distribution of these classifications is not sufficient in large populations. The aim of this study was to analyse the preoperative knee morphology with regard to the aforementioned classifications in long leg radiographs prior to total knee arthroplasty surgery using Artificial Intelligence.

METHODS

The cohort comprised 8739 preoperative long leg radiographs of 7456 patients of all total knee arthroplasty surgeries between 2009 and 2021 from our institutional database. The automated measurements were performed with the validated Artificial Intelligence software LAMA (ImageBiopsy Lab, Vienna) and included standardized axes and angles [hip-knee-ankle angle (HKA), mechanical lateral distal femur angle (mLDFA), mechanical medial proximal tibia angle (mMPTA), mechanical axis deviation (MAD), anatomic mechanic axis deviation (AMA) and joint line convergence angle (JLCA)]. CPAK and functional phenotype classifications were performed and all measurements were analysed for gender, age, and body mass index (BMI) within these subgroups.

RESULTS

Varus alignment was more common in men (m: 2008, 68.5%; f: 2953, 50.8%) while neutral (m: 578, 19.7%; f: 1357, 23.4%) and valgus (m: 345, 11.8%; f: 1498, 25.8%) alignment was more common in women. The most common morphotypes according to CPAK classification were CPAK Type I (2454; 28.1%), Type II (2383; 27.3%), and Type III (1830; 20.9%). An apex proximal joint line (CPAK Type VII, VIII and IX) was only found in 1.3% of all cases (n = 121). In men, CPAK Type I (1136; 38.8%) and CPAK Type II (799; 27.3%) were the most common types and women were spread more equally between CPAK Type I (1318; 22.7%), Type II (1584; 27.3%) and Type III (1494; 25.7%) (p < 0.001). The most common combination of femur and tibia types was NEUmLDFA0°,NEUmMPTA0° (m: 514, 17.5%; f: 1004, 17.3%), but men showed femoral varus more often. Patients with a higher BMI showed a significantly lower age at surgery (R2 = 0.09, p < 0.001). There were significant differences between men and women for all radiographic parameters (p < 0.001).

CONCLUSION

Distribution in knee morphology with gender-specific differences highlights the wide range in osteoarthritic knees, characterized by CPAK and phenotype classification and may influence future surgical planning.

LEVEL OF EVIDENCE

Level III.

Complications after lateral unicompartmental knee arthroplasty in a fast-track setting: a prospective cohort study of 170 procedures

BACKGROUND AND PURPOSE

In existing studies on fasttrack unicompartmental knee arthroplasty (UKA), the majority of surgeries are medial. There are substantial differences between lateral and medial UKA, which is why outcomes cannot automatically be compared. To gain information on the feasibility and safety of fast-track protocols in lateral UKAs, we investigated length of stay (LOS) and early complications after lateral UKA, performed using a fast-track protocol in well-established fast-track centers.

PATIENTS AND METHODS

We retrospectively evaluated prospectively collected data on patients undergoing lateral UKA in a fast-track setup from 2010 to 2018 at 7 Danish fast-track centers. Data on patient characteristics, LOS, complications, reoperations, and revisions was analyzed using descriptive statistics. Safety and feasibility were defined as complication and reoperation rates within 90 days comparable to non-fast track lateral UKA or fast-track medial UKA.

RESULTS

We included 170 of patients with a mean age of 66 (SD 12) years. Median LOS was 1 day (interquartile range 1-1), which was unchanged from 2012-2018. 18% were discharged on the day of surgery. Within 90 days, 7 patients experienced medical complications and 5 patients experienced surgical complications. 3 patients underwent reoperation, 2 were soft tissue revisions and the third was removal of an exostosis due to catching of the patella. 1 patient was revised due to a bearing dislocation.

CONCLUSION

Our findings suggest that lateral UKA in a fast-track setting is feasible and safe.

Robotic-Arm-Assisted Lateral Unicompartmental Knee Arthroplasty with a Fixed-Bearing Implant

Background

Approximately 5% to 10% of patients with knee arthritis have isolated lateral compartment arthritis; however, lateral unicompartmental knee arthroplasty (UKA) comprises just 1% of all knee arthroplasties1. This low proportion is partly because of the perceived complexity of lateral UKA and concerns over implant longevity and survivorship compared with total knee arthroplasty (TKA)2,3. With an improved understanding of knee kinematics alongside advances in implant design and tools to aid in appropriate restoration of limb alignment, lateral UKA can be an appealing surgical alternative to TKA for certain patients with lateral knee arthritis4,5. In appropriately selected patients, lateral UKA has been associated with reduced osseous and soft-tissue resection, more natural knee kinematics, less pain, shorter hospitalization, decreased blood loss and infection rates, and excellent survivorship and patient-reported outcomes6-9.

Description

This surgical approach and technique described for lateral UKA utilizes robotic-arm assistance and modern fixed-bearing implants10. The specific steps involve appropriate patient evaluation and selection, extensive radiographic and computed-tomography-based preoperative templating, a lateral parapatellar approach, intraoperative confirmation of component position and alignment, and robotic-arm assistance to perform osseous resections to achieve limb alignment and kinematic targets10. Final implants are cemented in place, and patients typically are discharged home on the day of surgery10.

Alternatives

Nonoperative treatment for end-stage knee arthritis includes weight loss, activity modification, assistive devices, bracing, nonsteroidal anti-inflammatory medications, and various injections11. Alternative surgical treatments include TKA4 and, in certain patients, an offloading periarticular osteotomy12.

Rationale

Lateral UKA is an appealing surgical option for nonobese patients who have disabling knee pain isolated to the lateral compartment, good preoperative range of motion, and a passively correctable valgus limb deformity10,13.

Expected Outcomes

Patients are typically discharged home on the day of surgery, or occasionally on postoperative day 1 if medical comorbidities dictate hospital monitoring overnight10. Patients return to light activities, including walking, immediately postoperatively. By 3 months postoperatively, patients will generally have returned to all desired activities9. The mid-term outcomes of this procedure, as performed by the corresponding author, have been published recently14,15. The 5-year survivorship of 171 lateral UKAs was 97.7%, with 72.8% of patients reporting that they were very satisfied with their procedure and 19.8%, that they were satisfied14. Only 3.8% of patients reported dissatisfaction with their lateral UKA14. The mean Knee Injury and Osteoarthritis Outcome Score (KOOS) and standard deviation were 85.6 ± 14.314. These outcomes did not differ from those observed in 802 medial UKAs, which showed a survivorship of 97.8% and KOOS of 84.3 ± 15.914. These findings are generally in line with previously published studies, which have demonstrated excellent survivorship and patient-reported outcomes with fixed-bearing lateral UKA16-19.

Important Tips

Component position and alignment are critical to achieve target knee kinematics.Target postoperative alignment is 1° to 4° of valgus.A meticulous cementation technique is required for optimal fixation and avoidance of excess residual cement in the posterior knee.

Acronyms and Abbreviations

ACL = anterior cruciate ligamentAP = anteroposteriorBMI = body mass indexCT = computed tomographyCAT = computed axial tomographyIT = iliotibialKOOS JR = Knee Injury and Osteoarthritis Outcome Score for Joint ReplacementMCL = medial collateral ligamentMRI = magnetic resonance imagingOR = operating roomPFJ = patellofemoral jointpoly = polyethyleneROM = range of motionTKA = total knee arthroplastyUKA = unicompartmental knee arthroplasty.

Patella resurfacing is not associated with a difference in the Oxford knee score after total knee arthroplasty but stair descent is enhanced

BACKGROUND

The primary aim was to assess the Oxford knee scores (OKS) on patients who underwent a total knee arthroplasty (TKA) with patellar resurfacing compared to those who did not. Secondary aims were to identify: (1) factors associated with resurfacing, (2) the effect of resurfacing on specific components of the OKS related to patellofemoral function, (3) the influence on patient satisfaction, and (4) whether a subgroup of patients had an improved outcome when resurfacing was undertaken.

METHODS

A retrospective cohort study was undertaken using outcome data from the arthroplasty database held at the study centre. Patient demographics and OKS were collected preoperatively and at 1 and 2 years postoperatively. Patient satisfaction was assessed at 1 and 2 years postoperatively.

RESULTS

Three thousand one hundred and twenty-two patients met the inclusion criteria of which 46.5% (n = 1453) underwent resurfacing. There were no differences in the OKS change at 1 or 2 years between those undergoing and not undergoing resurfacing (difference 0.2, p ≥ 0.469). Patients undergoing resurfacing were more likely to be female (odds ratio (OR) 1.53, 95% CI 1.30-1.79, p < 0.001), undergo a posterior stabilised knee (OR 6.87, 95% CI 5.71-8.27, p < 0.001) or had a worse response to question 5-standing from a chair, (p = 0.011) or 12-stair descent, (p = 0.017) of the OKS preoperatively. There was no difference in postoperative patient satisfaction (p ≥ 0.180). There was a significantly greater improvement in question 12 of the OKS at 1 year (p = 0.019) in the resurfaced group. There were no patient-related factors or symptoms that were associated with a clinically significant (≥ 5 points) greater postoperative OKS.

CONCLUSION

Patella resurfacing was not associated with a clinically important improvement in OKS. No specific indications for patella resurfacing were identified that offered an improved outcome, but when it was undertaken there was a greater improvement in the ability to descend stairs. Level of evidence Retrospective diagnostic study, Level III.

Surgical principles for complex primary total knee arthroplasty in the presence of extra-articular deformity

Background

Accurate restoration of alignment is vital to the success of a total knee arthroplasty (TKA) procedure. Deformities, whether these are intra-articular and/or extra-articular AND/OR whether these are uniplanar/multiplanar/complex, can impose varying technical challenges in surgical planning and execution. Literature on performing TKA in presence of limb deformity is limited, especially for extra-articular deformities.

Objectives

The objectives of this narrative review are twofold. Firstly, we analyse the existing English literature for studies focussed on TKA and deformity correction and summarise the important points about deformity pathomechanics, clinical and radiological assessment, pre-operative planning and surgical techniques. The second objective is to provide the readers with a simplistic and wholistic management algorithm to assist surgeons in meticulous planning to tackle the technical challenges imposed by lower limb deformities while performing a TKA.

Discussion

Approach to each patient must be holistic and customised on an individual basis according to patient characteristics, deformity characteristics and surgeon experience. The three main options available are: (1) Primary TKA (symmetric cuts/asymmetric cuts with/without computer navigation assistance) (2) Single stage corrective osteotomy and TKA and (3) Two-staged deformity correction and TKA. A multi-disciplinary team approach is required and a knee surgeon well-versed in revision arthroplasty and a limb reconstruction surgeon specialising in deformity correction, should be involved from the outset. The use of computer navigation technology, particularly for deformity correction and TKA, has increased over the last couple of decades and is recommended by the authors for these challenging cases.

Lateral unicompartmental knee arthroplasty (UKA) showed a lower risk of failure compared to medial unicompartmental knee arthroplasty in the Register of Prosthetic Orthopedic Implants (RIPO)

INTRODUCTION

The present study aimed to investigate differences in survivorship between medial and lateral unicompartmental knee arthroplasty (UKA) by analyzing the data of an Italian regional registry. The hypothesis was that, according to recent literature, lateral implants have comparable survivorship with regard to the medial implants.

MATERIALS AND METHODS

The Register of Orthopaedic Prosthetic Implants (RIPO) of Emilia-Romagna (Italy) database was searched for all UKAs between July 1, 2000, and December 31, 2019. For both cohorts, subject demographics and reasons for revision were presented as a percentage of the total cohort. Kaplan-Meier survivorship analysis was performed using revision of any component as the endpoint and survival times of unrevised UKAs taken as the last observation date (December 31, 2019, or date of death).

RESULTS

Patients living outside the region and symmetrical implants (which do not allow the compartment operated to be traced) were excluded. 5571 UKAs implanted on 5172 patients (5215 medial UKAs and 356 lateral UKAs) were included in the study. The survivorship analysis revealed 13 failures out of 356 lateral UKAs (3.7%) at a mean follow-up of 6.3 years and 495 failures out of 5215 medial UKAs (9.5%) at a mean follow-up of 6.7 years. The medial UKAs had a significantly higher risk of failure, with a Hazard Ratio of 2.6 (CI 95% 1.6-4.8; p < 0.001), adjusted for age, gender, weight, and mobility of the insert. Both the groups revealed a good survival rate, with 95.2% of lateral implants and 87.5% of medial implants still in situ at 10 years of follow-up.

CONCLUSIONS

Lateral UKA is a safe procedure showing longer survivorship than medial UKAs (95.2% and 87.5% at 10 years, respectively) in the present study.

LEVEL OF EVIDENCE

Level 3, therapeutic study.

Correlation between goniometric measurements of range of motion and radiographic scores in osteoarthritis knee: An observational study among females

Osteoarthritis (OA) is a chronic degenerative joint disease. Different radiological changes are found according to grades. Range of motions (ROMs) of knee decreases with severity of OA. Women are more sufferer than men in OA knee. Objective was to correlate goniometric ROM with Kellgren-Lawrence (KL) radiographic score of female osteoarthritic knee. The study was a cross-sectional study conducted in Department of Physical Medicine and Rehabilitation, BSMMU, Dhaka, from February 2020 to March 2021. According to ACR (American College of Rheumatology) criteria, total 66 patients with primary OA knee were selected and examined in this study. Maximal flexion, extension, and rotation movements were measured by a universal goniometer. X-ray of standing both (A/P and lateral) view and skyline view of knee joint were taken and assessed with KL radiographic scores for medial, lateral, and patellofemoral compartments. Correlations between ROMs and KL scores were analyzed by Pearson correlation test. Among the 66 patients, mean age was 53.59 ± 7.19 years and mean body mass index was 26.62 ± 3.35. Majority (84.8%) of the patients were housewives. Mean maximum flexion was 126.71 ± 4.88°, maximum extension was -3.98 ± 1.74°, and internal and external rotations were 6.38 ± 1.29 and 8.48 ± 1.55°, respectively. More than half of patients had medial compartment KL score 3 or more while KL score 2 was found in 47% and 62.1% patients, respectively, in lateral and patellofemoral compartments. Statistically significant negative correlations were found between range of motion and radiographic scores. Strong correlation was present between maximal flexion and medial compartment score (r = -0.821, P < .001), whereas moderate correlation with other compartments. Extension values were moderately correlated with patellofemoral scores (r = -0.560, P < .001) and weakly correlated with rest of radiographic scores. Internal and external rotation were more related with medial compartment (r= -0.469, P < .001) and lateral compartment scores (r = -0.481, P < .001), respectively, than other compartment scores. There were significant negative correlations between goniometric measurements of knee ROM and radiographic scores in osteoarthritis knee in female patients.

Distal femoral osteotomy versus lateral unicompartmental arthroplasty for isolated lateral tibiofemoral osteoarthritis with intra-articular and extra-articular deformity: a propensity score-matched analysis

Purpose

Lateral unicompartmental arthroplasty (UKA) and distal femoral osteotomy (DFO) represent surgical solutions in cases of valgus malalignment and isolated lateral osteoarthritis (OA) of the knee. The aim of the present study was to assess the clinical results, complications, and the overall postoperative alignment of a series of DFO and lateral UKA with a minimum 2-year follow-up in active middle-aged patients.

Methods

Patients with valgus knee and isolated lateral OA who underwent opening-wedge DFO or UKA from 2017 to 2019 were reviewed. Each patient was characterized by a joint line convergence angle (JLCA) > 3° and mechanical lateral distal femoral angle (mLDFA) < 87°. We excluded patients who underwent meniscus or osteochondral allograft during DFO. The Oxford Knee Score (OKS), Knee Injury and Osteoarthritis Outcome Score (KOOS), complications, and postoperative alignment were assessed. Propensity score matching was used to identify comparable patients.

Results

The DFO and lateral UKA groups consisted of 29 patients each. No statistically significant differences in gender, age, body mass index (BMI), length of follow-up, or limb deformity were reported between the two groups. In the DFO group, OKS was reported to improve from 27.51 to 38.59 (p < 0.05) and KOOS from 51.14 to 67.2 (p < 0.05). Similarly, in the UKA group, OKS improved from 26.23 to 35.43 (p < 0.05) and KOOS from 50.12 to 65.91 (p < 0.05). However, the improvement in OKS and KOOS (delta) did not differ between groups (p = 0.35 and p = 0.95). The DFO and UKA groups were characterized by similar postoperative hip-knee-ankle (HKA) angle measurements of −3.26 and −3.00, respectively (p = 0.65). No patients in the UKA group underwent revision or other knee surgeries during follow-up. No infections were detected in either group. In the DFO group, no cases of nonunion or delayed union were reported. However, 40% of DFO patients underwent plate removal. One patient in each group was characterized by progression of medial OA with Kellgren-Lawrence (KL) grade > 3.

Conclusion

UKA and DFO represent an effective treatment in lateral knee OA with intra-articular and extra-articular deformity. Both surgeries were able to provide a significant and comparable clinical improvement.

Level of evidence: III, comparative retrospective cohort study.

Does Implant Design Influence Failure Rate of Lateral Unicompartmental Knee Arthroplasty? A Meta-Analysis

BACKGROUND

Lateral unicompartmental knee arthroplasty (UKA) is a viable solution for isolated lateral compartment arthritis. Several prosthetic designs are available such as fixed-bearing metal-backed (FB M-B), fixed-bearing all-polyethylene (FB A-P), and mobile-bearing metal-backed (MB M-B) implants. The purpose of this meta-analysis is to compare failure rates of different prosthetic designs.

METHODS

Preferred Reporting Items for Systematic Reviews and Meta-Analyses systematic review was conducted using 4 databases (MEDLINE, EMBASE, Cochrane, and PubMed) to identify all studies that investigate outcomes of lateral UKA. Twenty-one studies met the inclusion criteria, and failure rates were compared by implant type and follow-up time separately in order to assess potential confounding factors. Two separate analyses have been performed among different implant designs (FB M-B vs FB A-P vs MB M-B) and different follow-ups (<5 years, between 5 and 10 years, >10 years).

RESULTS

The failure rate of FB M-B lateral UKA was significantly lower compared to other lateral UKA designs present in the market (0.8% vs 8.6% and 7.1% for FB M-B, FB A-P, and MB M-B, respectively). No significative difference among groups has been detected when comparing all implants with regard to follow-up time.

CONCLUSION

Considering actual evidence, for a surgeon approaching lateral UKA, the FB M-B design is preferable, given the lower failure rates and subsequently a longer implant survivorship.

Consequences of Progressive Full-Thickness Focal Chondral Defects Involving the Medial and Lateral Femoral Condyles After Meniscectomy: A Biomechanical Study Using a Goat Model

Background:

Full-thickness chondral defects alter tibiofemoral joint homeostasis and, if left untreated, have the potential to progress to osteoarthritis.

Purpose:

To assess the effects of isolated and dual full-thickness chondral defect size and location on the biomechanical properties of the lateral femoral condyle (LFC) and medial femoral condyle (MFC) during dynamic knee flexion in goat knees without menisci.

Methods:

In 12 goat knees, we created progressively increasing full-thickness circular chondral defects (3-, 5-, and 7.5-mm diameter) in the weightbearing contact area of flexion and extension in the MFC, the LFC, or both. Each knee was fixed into a custom steel frame and attached to a motor with sensors inserted intra-articularly. For each testing condition, the knee was loaded to 100 N and underwent a dynamic range of motion between 90° of flexion and 30° of extension. The following parameters were collected: contact area, contact pressure, contact force, peak area, and peak pressure.

Study Design:

Controlled laboratory study.

Results:

The peak pressure at the defect rim of the MFC at full extension increased by 51.51% from no defect (1.887 MPa) to a 7.5-mm defect (2.859 MPa) (P < .001), and the peak pressure at the defect rim of the LFC at full extension increased by 139.14% from no defect (1.704 MPa) to a 7.5-mm defect (4.075 MPa) (P < .001). The peak pressures for LFC defects at all 3 diameters were significantly greater when compared with dual defects consisting of increasing LFC defect diameter and constant MFC defect diameter (P < .001 for all).

Conclusion:

Extremely large increases in peak pressure were seen at the rim of articular cartilage defects when evaluated under dynamic loading conditions. Isolated LFC defects experienced a greater increase in defect rim stress concentrations when compared with isolated MFC defects for equivalent increases in defect size. Defect size played a significant role independent of location for peak pressures on the MFC and LFC.

Clinical Relevance:

Significant rim-loading effects increase with defect size under dynamic loading and may result in increasingly rapid progression of articular cartilage lesions. Within the context of this goat model, findings suggest that lateral compartment chondral lesions are more likely to progress than medial compartment lesions of equivalent size.

Midterm Outcomes in Lateral Unicompartment Knee Replacement: The Effect of Patient Age and Bearing Choice

Isolated lateral compartment knee osteoarthritis (OA) affects between 7 and 10% of patients with knee OA. Although lateral unicompartmental knee arthroplasty (UKA) is an accepted treatment to manage this condition, it is performed relatively infrequently. The aim of this study was to evaluate the mid-term survivorship, radiographic outcomes, and patient-reported outcome measures (PROMs). We performed a retrospective review of a prospectively maintained database of consecutive isolated lateral UKAs performed by a single surgeon at an academic institution between September 2007 and December 2015. Our primary outcome was failure defined as revision surgery to total knee arthroplasty (TKA). Secondary outcomes included any additional surgery for any other reason. Forty-nine consecutive patients (27 females) with median age of 54.7 years (45.2-82.2) met the inclusion criteria. The survival rate for the whole cohort was 86.1% (95% confidence interval [CI]: 73.2-99.0) at 10 years as defined by conversion to TKA. There were a total of four lateral UKAs (all mobile bearings) revised to TKAs. The entire cohort demonstrated statistically significant improvements from preoperative PROMs compared with the most recent postoperative PROMs including the Western Ontario and McMaster Universities Osteoarthritis Index, Knee injury and Osteoarthritis Outcome Score, and Tegner activity scale at a median 8.8 (1.7-12.2) years follow-up. Patients with mobile bearing underwent higher revision to TKA and reoperation for all indications compared with fixed-bearing lateral UKA. In this relatively young cohort, lateral UKA yielded acceptable long-term survival and satisfactory improvement in functional outcomes. Patients who had fixed-bearing implants had similar improvement and trended toward lower revision rates than those with mobile-bearing implants. Level III therapeutic: retrospective Study was performed.

Early results of fixed-bearing unicompartmental knee replacement designed for the lateral compartment

Background

Isolated lateral compartment knee arthritis is less prevalent than medial. While the reported results of medial unicompartmental knee replacement (UKR) have been good and comparable to total knee replacement, the results of lateral UKR have been mixed. We present the short-term results and survivorship of a fixed-bearing UKR designed specifically for the lateral compartment.

Methods

We report the result of 130 primary fixed-bearing lateral Oxford (FLO) UKRs (123 patients) performed between 2015 and 2019 with a minimum follow-up of 1 year. The indications for lateral UKR were: isolated lateral osteoarthritis (n = 122), post-trauma (n = 5) and osteonecrosis (n = 3). The mean age was 69.1 (± 11.6), mean BMI 28.4 (± 4.9), 66.9% female, 60% right-sided, and mean follow-up 3 (range 1–4.8 years, standard deviation ± 1) years. The primary outcome measure was the Oxford knee score (OKS). Survival analysis was performed with “revision for any reason”, “reoperation”, and “implant failure” as the endpoints.

Results

Six patients died from unrelated reasons. None of the implants failed. One required the addition of a medial UKR for medial arthritis. There were no other reoperations. At 4 years, the survival for implant failure was 100% and for both revision and all reoperations was 99.5% (95% CI 96.7–99.9%). At the last review, at a mean of 3 years, the mean Oxford knee score was 41.

Conclusion

The good survivorship and outcome scores suggest that UKR designed for the lateral compartment is an excellent alternative to total knee replacement in selected patients with isolated lateral tibiofemoral arthritis at short-term follow-up.

Cemented Lateral Unicompartmental Knee Replacement: A retrospective single centre independent series

Background

Unicompartmental knee replacement (UKR) has functional and economic benefits when compared with total knee replacement, however it is technically demanding and may be associated with higher failure rates. The primary aim of this independent series study was to evaluate the survival of lateral UKRs implanted in our institution and their clinical outcomes. The secondary outcome was to compare the results of mobile and fixed-bearing prostheses.

Methods

This is a retrospective series study of 183 cemented lateral UKRs implanted in 170 patients, for advanced isolated lateral compartment arthritis, under the care of two senior surgeons. Fixed or mobile-bearing prostheses were used according to the surgeon's preference. Kaplan Meier analysis was used to evaluate prosthesis survival with the endpoint being revision for any reason. A subgroup analysis of survival was also done for each bearing type. Functional outcomes were evaluated using the Oxford knee score (OKS) at final follow-up.

Results

This series included 103 Fixed-bearing and 80 mobile-bearing prostheses. Median follow-up was 6.9 years. 9 knees required revision. The commonest reason for revision was progression of arthritis to the medial compartment. Dislocation was the commonest cause of revision in the mobile-bearing group. Survival at 10 years was 91.9% with no significant difference ( p = 0.083) between bearing types (fixed-bearing 93.8% and mobile-bearing 90.6%). The OKS were comparable in both groups, the mean OKS was 44/48.

Conclusion

Good survival and functional outcomes can be achieved using cemented lateral UKRs with both bearing types. There was a trend towards superior outcomes in the fixed-bearing group.

Functional results and survivorship after medial unicompartmental knee arthroplasty: a single center experience from Saudi Arabia

BACKGROUND

Isolated involvement of the medial compartment of the knee in degenerative disease is encountered in about 25% of patients with gonarthrosis. We aim to show that in a well-selected group of such patients, medial unicompartmental knee arthroplasty (UKA) is a good option.

OBJECTIVES

Review the functional outcomes of patients undergoing UKA and determine the long-term survivorship of the implants and complications of the procedure.

DESIGN

Analytical retrospective chart review.

SETTING

Academic tertiary care medical center and tertiary care private hospital in the western region of Saudi Arabia.

PATIENTS AND METHODS

We selected patients who underwent medial UKAs by the same surgeon between December 1988 and December 2009. The life table approach and the Kaplan-Meier statistical method were used to estimate the survival rate (5-30 years) with revision as the endpoint. Functional outcome scores were determined according to the Knee Society Clinical Rating System.

MAIN OUTCOME MEASURES

Change in performance scores for pain, walking, and range of movement. Survivorship of the implants with removal of the implant as the endpoint; post-operative complications.

SAMPLE SIZE

218 implants on 142 patients.

RESULTS

The survival rate of UKA was 94.7% at 10 years (95% CI 0.906-0.970), 80.9% at 20 years (95%CI 0.724-0.871), and 77.8% at 30 years (95%CI 0.669-0.855). The average grand total functional score increased from 61 (maximum 200) at 0 months to above 150 at ≥6 months.

CONCLUSION

UKA is a good option for isolated medial compartment gonarthrosis with excellent functional outcome and good survivorship in selected patients.

LIMITATION

Single center experience, retrospective. We lost 6.0% of patients during follow-up. Comparison with other treatment modalities is based on literature review and not on our own data.

CONFLICT OF INTEREST

None.

Excellent outcomes for lateral unicompartmental knee arthroplasty: Multicenter 268-case series at 5 to 23 years' follow-up

INTRODUCTION

Isolated lateral compartment osteoarthritis of the knee (LCOA) is 10 times less frequent than medial compartment involvement. Long-term assessments of unicompartmental knee arthroplasty (UKA) in this indication are rare, with small series.

HYPOTHESIS

Survival and functional outcome of lateral UKA in a large series are quite acceptable; the strategy is suited for isolated LCOA.

MATERIAL AND METHOD

A multicenter retrospective study in 6 French health establishments included all lateral UKAs performed between January 1988 and September 2014. Clinical data (range of motion, International Knee Society (IKS) knee and function scores, satisfaction), paraclinical data (radiologic angles) and complications were prospectively entered in medical files during follow-up and analyzed retrospectively at end of follow-up.

RESULTS

During the study period, 311 lateral UKAs were performed in 295 patients, using 5 fixed-bearing implant models. Twenty-eight patients died within 5 years, and 15 (4.8%) were lost to follow-up. The series thus comprised 268 lateral UKAs in 63 male and 205 female patients, with a mean age of 68.8±10.5 years, including 7 cases of post-traumatic osteoarthritis and 4 of aseptic osteonecrosis. Mean follow-up was 9.1 years (range, 5-23 years), implant survivorship with failure defined as all-cause revision surgery was 85.4% at 10 years and 79.4% at 20 years. At last follow-up, IKS knee score was 87.0 and IKS function score 80.2. Maximal flexion was 125°. 94.3% of patients were satisfied or very satisfied. The main cause of revision surgery was osteoarthritis in another knee compartment (66,7%, n=26).

CONCLUSION

Lateral UKA showed good survivorship, comparable to medial UKA, with good functional results and excellent long-term satisfaction.

LEVEL OF EVIDENCE

IV, retrospective cohort study.

A Comprehensive Evaluation of Lateral Unicompartmental Knee Arthroplasty Short to Mid-Term Survivorship, and the Effect of Patient and Implant Characteristics: An Analysis of Data From the Dutch Arthroplasty Register

BACKGROUND

The rarity of lateral unicompartmental knee arthroplasty (UKA) results in a lack of large cohort studies and understanding. The aim of this study is to comprehensively evaluate survivorship of lateral UKA with registry data and compare this to medial UKA.

METHODS

Lateral (n = 537) and medial UKAs (n = 19,295) in 2007-2017 were selected from the Dutch Arthroplasty Register. Survival analyses were performed with revision for any reason as primary endpoint. Adjustments were made for patient and implant characteristics. Stratified analyses according to patient and implant characteristics were performed. Reasons and type of revision were grouped according to laterality and bearing design.

RESULTS

The 5-year revision rate was 12.9% for lateral UKA and 9.3% for medial UKA. Multivariable regression analyses showed no significant increased risk for revision for lateral UKA (hazard ratio 0.87, 95% confidence interval 0.66-1.15). Stratified analyses showed that the effect of patient characteristics on revision was comparable between lateral and medial UKA; however, the use of mobile-bearing design for lateral UKA was associated with increased revision rate. Progression of osteoarthritis was the main reason for revision on both sides accompanied by tibia component loosening for medial UKA. Reasons and type of revision varied depending on bearing design.

CONCLUSION

Similar survivorship of lateral and medial UKA was reported. Specifically, there is a notable risk for revision when using mobile-bearing designs for lateral UKA. Failure modes and type of revision depends on laterality and bearing design. These findings emphasize that surgical challenges related to anatomy and kinematics of the lateral and medial knee compartment need to be considered.

Technique for Medial Closing-Wedge Proximal Tibia Osteotomy in the Valgus Knee

Valgus malalignment can be corrected with a medial closing-wedge proximal tibia osteotomy in patients with symptomatic lateral compartment disease. Advantages of this technique include the inherent stability of the closing wedge with direct bone contact and reliable healing that enables early weight bearing and shorter recovery time. In addition, a tibial-based osteotomy alters joint contact forces in both flexion and extension versus femoral-based osteotomies. The purpose of this article is to present a reproducible technique for medial closing-wedge proximal tibia osteotomy and review the indications, preoperative planning, rationale, and clinical outcomes.

Could knee joint mechanics during the golf swing be contributing to chronic knee injuries in professional golfers?

Full three-dimensional movements and external moments in golfers' knees and the possible involvement in injuries have not been evaluated using motion capture at high sample frequencies. This study measured joint angles and external moments around the three anatomical axes in both knees of 10 professional golfers performing golf drives whilst standing on two force plates in a motion capture laboratory. Significant differences were found in the knee joint moments between the lead and trail limbs for the peak values and throughout all stages during the swing phase. A significantly higher net abduction moment impulse was seen in the trail limb compared with the lead limb (-0.518 vs. -0.135 Nms.kg^-1), indicating greater loading over the whole swing, which could contribute to knee lateral compartment or anterior cruciate ligament injuries. A significant correlation (r = -0.85) between clubhead speed at ball contact and maximum joint moment was found, with the largest correlations being found for joint moments at the top of the backswing event and at the end of the follow-through. Therefore, although knee moments can contribute to high clubhead speeds, the large moments and impulses suggest that they may also contribute to chronic knee injuries or exacerbate existing conditions.

High Survival Rate and Very Low Wear of Lateral Unicompartmental Arthroplasty at Long Term: A Case Series of 54 Cases at a Mean Follow-Up of 17 Years

BACKGROUND

Survivorship of lateral unicompartmental knee arthroplasty (UKA) has progressively improved. However, there are few studies describing long-term results, and no study reports on polyethylene (PE) wear in lateral unicompartmental arthroplasty. The aims of this study are to determine the survival rate of lateral UKA with a fixed, all-PE bearing, and the PE wear of the tibial implant at a minimum of 15 years follow-up.

METHODS

From January 1988 to October 2003, we performed 54 lateral UKAs in 52 patients. All patients had isolated lateral osteoarthritis (OA). The mean age at the index procedure was 65.4 ± 11 years. Thirty-nine UKAs were available for follow-up (30 alive and 9 dead after 15 years). Twelve patients had died before 15 years and 3 patients were lost to follow-up. The mean follow-up was 17.9 years (range, 15-23 years).

RESULTS

At the final follow-up, 8 knees of 39 (20.5%) had a surgical revision. The cumulative survival rate was 82.1% at 15 years and 79.4% at 20 years. The main reason of revision was progression of OA (87.5%), followed by aseptic loosening of the tibial component (12.5%). With a mean follow-up of 17.9 years, the mean PE wear was 0.061 mm/y. There was no radiographic loosening in the surviving implants and no revisions for wear. The mean functional International Knee Society score was 66.5 ± 26.8, with a mean objective score of 84.4 points ± 13.2. In the population without revision, 90.5% were satisfied or very satisfied at the latest follow-up.

CONCLUSION

Lateral UKA with a fixed, all-PE tibial bearing and a femoral resurfacing implant presents a high survivorship at long term, with very low PE wear.

Primary Cells Isolated from Human Knee Cartilage Reveal Decreased Prevalence of Progenitor Cells but Comparable Biological Potential During Osteoarthritic Disease Progression

BACKGROUND

Current decisions on cellular therapies for osteoarthritis are based primarily on clinical experience or on assumptions about preferred cell sourcing. They have not been informed by rigorous standardized measurements of the chondrogenic connective-tissue progenitors (CTP-Cs) or their intrinsic diversity of chondrogenic potential. The goal of this study was to quantitatively define the CTP-Cs resident in cartilage of different grades of osteoarthritis and to compare their concentration, prevalence, and biological potential.

METHODS

Twenty-three patients who had varus malalignment of the knee and were scheduled to undergo elective total knee arthroplasty for idiopathic osteoarthritis and who had grade 1-2 osteoarthritis on the lateral femoral condyle and grade 3-4 osteoarthritis on the medial femoral condyle were recruited for study of the cartilage removed during surgery. CTP-Cs were assayed by a standardized colony-forming-unit assay using automated image-analysis software based on ASTM standard test method F2944-12.

RESULTS

Cell concentration was significantly greater (p < 0.001) in grade 3-4 cartilage than in grade 1-2 cartilage. The prevalence of CTP-Cs varied widely, but it trended lower in grade 3-4 cartilage than in grade 1-2 samples (p = 0.078). The biological performance of CTP-Cs from grade 1-2 and grade 3-4 cartilage was comparable. Increased cell concentration was a significant predictor of decreased CTP-C prevalence (p = 0.002).

CONCLUSIONS

Although grade 3-4 cartilage showed fewer CTP-Cs than grade 1-2 cartilage, the range of biological performance was comparable, which suggests that either may be used as a source for potent CTP-Cs. However, the biological reason for the heterogeneity of CTP-Cs in cartilage and the biological implications of that heterogeneity are not well understood and require further study.

CLINICAL RELEVANCE

In order to improve the efficacy of cartilage cell therapy procedures, it is key to characterize the quality and quantity of the cells and progenitors being administered. Additionally, understanding the heterogeneity in order to select appropriate subsets of populations will improve the rigor of decisions concerning cell sourcing and targeting for pharmacological and cellular therapies.

Comparison of Gait Biomechanics in Patients with and without Knee Osteoarthritis during Different Phases of Gait

Background

This study aimed to characterise knee adduction angles (KAA) and knee adduction moments (KAM) and compare this with foot centre of pressure (COP) in volunteers with and without knee osteoarthritis (OA).

Methods

A total of 108 participants were recruited; 84 had no known pathology, 18 had medial knee OA, and six had lateral knee OA. Linear regression was used to determine correlations between the normalised COP, KAM, and KAA during each phase of gait for all participants.

Results

The first phase of gait demonstrated significant differences between groups for all measures: KAA in all phases, COP in phases one and two, and KAM in phase one only.

Conclusion

The largest mechanical changes are seen in the first phase of gait in osteoarthritic patients. Although COP is an easy to measure tool, it is not as sensitive as KAA and did not demonstrate a significant difference between healthy and medial OA patients.

High occurrence of osteoarthritic histopathological features unaccounted for by traditional scoring systems in lateral femoral condyles from total knee arthroplasty patients with varus alignment

Background and purpose - A better understanding of the patterns and variation in initiation and progression of osteoarthritis (OA) in the knee may influence the design of therapies to prevent or slow disease progression. By studying cartilage from the human lateral femoral condyle (LFC), we aimed to: (1) assess specimen distribution into early, mild, moderate, and severe OA as per the established histopathological scoring systems (HHGS and OARSI); and (2) evaluate whether these 2 scoring systems provide sufficient tools for characterizing all the features and variation in patterns of OA. Patients and methods - 2 LFC osteochondral specimens (4 x 4 x 8 mm) were collected from 50 patients with idiopathic OA varus knee and radiographically preserved lateral compartment joint space undergoing total knee arthroplasty. These were fixed, sectioned, and stained with HE and Safranin O-Fast Green (SafO). Results - The histopathological OA severity distribution of the 100 specimens was: 6 early, 62 mild, 30 moderate, and 2 severe. Overall, 45/100 specimens were successfully scored by both HHGS and OARSI: 12 displayed low OA score and 33 displayed cartilage surface changes associated with other histopathological features. However, 55/100 samples exhibited low surface structure scores, but were deemed to be inadequately scored by HHGS and OARSI because of anomalous features in the deeper zones not accounted for by these systems: 27 exhibited both SafO and tidemark abnormal features, 16 exhibited only SafO abnormal features, and 12 exhibited tidemark abnormal features. Interpretation - LFC specimens were scored as mild to moderate OA by HHGS and OARSI. Yet, several specimens exhibited deep zone anomalies while maintaining good surface structure, inconsistent with mild OA. Overall, a better classification of these anomalous histopathological features could help better understand idiopathic OA and potentially recognize different subgroups of disease.

Osteoarthritis of the knee

Osteoarthritis of the knee is a degenerative condition that is commonly seen in the elderly population and sometimes occurs earlier in the athletic population. Pain and stiffness are common features, which can be debilitating. Clinical assessment of the knee joint requires consideration of its associated muscles, ligaments, tendons, bursae and menisci. The aim of this article is to provide an overview of knee pain assessment, to discuss the diagnosis of knee osteoarthritis, and to review some evidence-based management options.

The effect of implant position on bone strain following lateral unicompartmental knee arthroplasty: A Biomechanical Model Using Digital Image Correlation

Objectives

Unicompartmental knee arthroplasty (UKA) is a demanding procedure, with tibial component subsidence or pain from high tibial strain being potential causes of revision. The optimal position in terms of load transfer has not been documented for lateral UKA. Our aim was to determine the effect of tibial component position on proximal tibial strain.

Methods

A total of 16 composite tibias were implanted with an Oxford Domed Lateral Partial Knee implant using cutting guides to define tibial slope and resection depth. Four implant positions were assessed: standard (5° posterior slope); 10° posterior slope; 5° reverse tibial slope; and 4 mm increased tibial resection. Using an electrodynamic axial-torsional materials testing machine (Instron 5565), a compressive load of 1.5 kN was applied at 60 N/s on a meniscal bearing via a matching femoral component. Tibial strain beneath the implant was measured using a calibrated Digital Image Correlation system.

Results

A 5° increase in tibial component posterior slope resulted in a 53% increase in mean major principal strain in the posterior tibial zone adjacent to the implant (p = 0.003). The highest strains for all implant positions were recorded in the anterior cortex 2 cm to 3 cm distal to the implant. Posteriorly, strain tended to decrease with increasing distance from the implant. Lateral cortical strain showed no significant relationship with implant position.

Conclusion

Relatively small changes in implant position and orientation may significantly affect tibial cortical strain. Avoidance of excessive posterior tibial slope may be advisable during lateral UKA.

Cite this article: A. M. Ali, S. D. S. Newman, P. A. Hooper, C. M. Davies, J. P. Cobb. The effect of implant position on bone strain following lateral unicompartmental knee arthroplasty: A Biomechanical Model Using Digital Image Correlation. Bone Joint Res 2017;6:522–529. DOI: 10.1302/2046-3758.68.BJR-2017-0067.R1.

Insights into osteoarthritis progression revealed by analyses of both knee tibiofemoral compartments

OBJECTIVE

To identify disease relevant genes and pathways associated with knee Osteoarthritis (OA) progression in human subjects using medial and lateral compartment dominant OA knee tissue.

DESIGN

Gene expression of knee cartilage was comprehensively assessed for three regions of interest from human medial dominant OA (n = 10) and non-OA (n = 6) specimens. Histology and gene expression were compared for the regions with minimal degeneration, moderate degeneration and significant degeneration. Agilent whole-genome microarray was performed and data were analyzed using Agilent GeneSpring GX11.5. Significant differentially regulated genes were further investigated by Ingenuity Pathway Analysis (IPA) to identify functional categories. To confirm their association with disease severity as opposed to site within the knee, 30 differentially expressed genes, identified by microarray, were analyzed by quantitative reverse-transcription polymerase chain reaction on additional medial (n = 16) and lateral (n = 10) compartment dominant knee OA samples.

RESULTS

A total of 767 genes were differentially expressed ≥ two-fold (P ≤ 0.05) in lesion compared to relatively intact regions. Analysis of these data by IPA predicted biological functions related to an imbalance of anabolism and catabolism of cartilage matrix components. Up-regulated expression of IL11, POSTN, TNFAIP6, and down-regulated expression of CHRDL2, MATN4, SPOCK3, VIT, PDE3B were significantly associated with OA progression and validated in both medial and lateral compartment dominant OA samples.

CONCLUSIONS

Our study provides a strategy for identifying targets whose modification may have the potential to ameliorate pathological alternations and progression of disease in cartilage and to serve as biomarkers for identifying individuals susceptible to progression.