Clinical Study On Lateral Cartilage Wear In Patients With Varus Deformity Knee Osteoarthritis

Objective(1)、The first objective was to analyze the gross features of articular cartilage wear in varus knee osteoarthritis, and discuss the particular wear pattern, together with their frequency of eligibility criteria for unicompartmental knee arthroplasty.(2)、The second objective was to investigate the correlation between CTX-II、IL-6、MMP-13 and lateral compartment wear in varus knee osteoarthritis and establish whether the biochemical factors play the key role in lateral compartment wear of varus knee.(3)、The third objective was to analyze the risk factors for lateral compartmental cartilage wear in varus knee osteoarthritis.MethodsThe study was divided into three parts, which were completed in different periods.(1)、Data collected from the dissection of knees with varus knee osteoarthritis undergone total knee arthropalstys from September 2012 to March 2013 were analysised. At the operation, the gross assessments of articular cartilage, ligament and meniscus were recorded, and then the slices were evaluated for histologic analysis. The cases with healthy lateral cartilage, intact anterior cruciate ligament (ACL) and posterior cruciate ligament(PCL), preoperative range of motion (ROM) greater than 90 degrees, flexion deformity less than 10 degrees, and genu varum less than 15 degrees were indicated for unicompartmental knee replacement(2)、Data prospectively collected from the varus knee osteoarthritis patients with lateral compartment wear who undergone total knee arthropalsty from June 2013 to June 2014 were analysised. At the operation, the gross assessment of lateral compartment articular cartilage was recorded, and then the slice was evaluated for histologic analysis. Synovial fluid was obtained by arthrocentesis. An equal number of patients from varus knee osteoarthritis without lateral compartment wear performed in the same period were selected and matched with respect to age, varus, preoperative range of motion and radiological grade of knee arthrosis. Synovial fluid concentrations of type II collagen C-terminal telopeptide (CTX-II),matrix metalloproteinase-13 (MMP-13), and interleukin-6 (IL-6) were evaluated by ELISA assay.(3)、Data prospectively collected from the dissection of 286 total knee arthropalsties (223 patients) with varus knee osteoarthritis from January 2013 to December 2013 were analyzed. At the operation, the gross assessments of articular cartilage, ligament and meniscus were recorded, and then the slices were evaluated for histologic analysis. Parameters of the patients with lateral compartmental cartilage wear were compared with those without lateral compartmental cartilage wear using the univariate analyses. Logistic regression analysis was used to analyze the risk factors associated with lateral compartmental cartilage wear.Results(1)、One hundred and forty eight knees with varus knee osteoarthritis in 113 patients who undergone total knee arthropalstys were included.The mean age was 66.2±8.4 years, varus degree was 7.6±4.8°. Wear patterns on the meidal compartmental surface showed that the areas involved in the majority of cases included middle and anterio-middle regions. The incidence of tibial middle and anterio-middle regions wear were 33.8%、27.7%, respectively. The incidence of the femoral middle region wear was 37.2%. The wear incidence of lateral compartmental was 22.3%. The mean thickness of the articular cartilage in tibial plateaus and femoral condyles from the weight bearing area at the meidal compartment were 0.97±0.93mm,1.17± 1.05mm, respectively. The thickness of the lateral articular cartilage in tibial plateaus and femoral condyles were 3.11±1.24mm,2.95±1.35mm, respectively.96 knees (64.9%) had intact ACL. The incidence of ACL-def iciency and absence was 27.7%,7.4%, respectively.20.3% cases would likely to be indicated for unicompartmental knee replacement.(2)、Histologic examination showed cartilage degeneration at a microscopic level in both groups. The concentrations of CTX-II, IL-6, MMP-13 in synovial fluid from the lateral compartment wear group were 111.8±55.7 ng/L,2.5±1.0 ng/L,134.4±33.1 ug/L, respectively. There were no difference comparing with the control group (CTX-II 91.7±57.1 ng/L, IL-6 2.1±0.5 ng/L, MMP-13 122.7±28.3 ug/L, respectively)(3)、Environmental factors showed no differences in age, side, gender, BMI, range of motion, and HSS score (P>0.05). Factors significantly increasing the risk of lateral compartmental cartilage wear by univariate analysis included varus degree, activity level, duration of onset, meniscus, Weidow grade, Kellgren-Lawrence grade, collateral ligament and anterior cruciate ligament (P<0.05). Multiple logistic regression analysis revealed the factors most highly associated with the increase risk for lateral compartmental wear were high activity level (OR=2.843,95% CI:1.010-8.002) and longer duration of onset (OR=1.216,95% CI:1.115-1.325). However, intact lateral meniscus (OR=0.012,95% CI:0.003-0.048) and anterior cruciate ligament (OR=0.406,95% CI:0.192-0.857) were associated with the protection of lateral compartmental.Conclusion(1)、In varus knee osteoarthritis undergone total knee arthroplasty, the middle third of both the femoral and tibial articular surfaces is most commonly involved in wears. The wear incidence of lateral compartmental was only 22.3%. It is potential to utilize UKA more frequently in the future.(2)、This study indicates that the biochemical factor may not play a key role in lateral compartment wear of varus knee osteoarthritis.(3)、In varus knee osteoarthritis, the wear incidence of lateral compartmental was low. High activity and increased duration of onset were risk factors of lateral compartmental wear. However, and intact meniscus and anterior cruciate ligament were protective factors.