Arthroscopic Mechanical Chondroplasty of the Knee Is Beneficial for Treatment of Focal Cartilage Lesions in the Absence of Concurrent Pathology

Abstract

Background: Articular cartilage lacks the ability for intrinsic repair after acute injury, and focal articular cartilage lesions cause significant morbidity worldwide. Arthroscopic debridement (chondroplasty) represents the majority of cartilage procedures of the knee; however, limited data exist regarding outcomes after chondroplasty performed in isolation of concurrent procedures or not as a primary treatment for osteoarthritis (OA).

Hypothesis: Arthroscopic mechanical chondroplasty is beneficial for patients with a focal cartilage lesion of the knee in the absence of meniscal pathology or OA.

Study design: Case series; Level of evidence, 4.

Methods: Potential participants were identified by querying billing data from a 3-year period in a single-surgeon practice, and eligible patients were verified to meet inclusion criteria through electronic medical record review. OA was quantified through Kellgren-Lawrence (KL) scoring. Subjective patient-reported outcome (PRO) scores, including International Knee Documentation Committee (IKDC), Knee injury and Osteoarthritis Outcome Score (KOOS), Western Ontario and McMaster Universities Arthritis Index (WOMAC), Tegner, Lysholm, and Veterans RAND 12-Item Health Survey (VR-12), were collected preoperatively and at follow-up intervals. International Cartilage Repair Society (ICRS) grade and lesion size were determined at arthroscopy. Linear regression was used to determine the effect of baseline score on final follow-up score. Correlated regression equations were used to assess the relationship of covariates and change in PRO scores.

Results: Fifty-three of 86 (62%) eligible participants completed postoperative questionnaires at an average of 31.5 months (range, 11.5-57 months). The mean patient age was 37.3 ± 9.7 years and mean body mass index (BMI) was 27.7 ± 5.6 kg/m²; 33 (62%) participants were women. The mean treated lesion size was 3.3 ± 1.9 cm², of these, 36 (68%) were ICRS grade 2 or 3, and 42 (79%) patients had a KL score of 0 to -2. On average, the cohort demonstrated significant improvement from baseline for almost all PRO scores. Regression analysis of change in score versus baseline indicated participants with lower preoperative scores gained more benefit from chondroplasty. Correlated regression equations showed KL score >0 and male sex had a consistent positive effect on change in PRO scores, high ICRS grade had a consistent negative effect, and lesion size, age, and obesity had no effect. Eight patients (15%) required further surgical intervention within the follow-up period.

Conclusion: The clinical efficacy of chondroplasty for repair of focal cartilage defects of the knee has not been studied in isolation from concurrent orthopaedic procedures. Our data show that arthroscopic mechanical chondroplasty is beneficial to patients, and response to surgical intervention is correlated with baseline PRO scores, sex, ICRS grade, and KL score.

Keywords: arthroscopy; articular cartilage; cartilage repair; chondroplasty.

Figure 1.

CONSORT (Consolidated Standards of Reporting Trials) diagram categorizing the cohort by patient enrollment, follow-up, and analysis. CPT, Current Procedural Terminology; EMR, electronic medical records; KL, Kellgren-Lawrence; PRO, patient-reported outcome.

Figure 2.

(A) Scatterplot of International Knee Documentation Committee (IKDC) final values (post) and baseline values (pre). The dashed line represents no change in final score from baseline score for all possible values. Data points above the line represent an improvement from baseline. (B) Histogram plot of improvement from baseline (change) for final follow-up scores. Dashed gray vertical line represents no change. On average, the group improved 23.3 points. The minimal interesting change for the IKDC from our model was 14.6 (dashed red line).

Figure 3.

Regression of change in International Knee Documentation Committee (IKDC) score versus the standardized baseline score. There was a statistically significant but weak correlation between IKDC change and baseline score (R ² = 0.31, P < .001). Vertical red bars indicate mean (42.7) and standard deviation units (approximately ± 20) of the baseline IKDC scores. Horizontal red lines indicate the average change from baseline (µΔ = 23.3) and the minimal interesting change (MIC = 14.6). MIC is based on the slope of the regression line and represents the expected change induced by standard deviation differences in baseline score. Note: if you follow the regression line from right to left starting at where it crosses 0, the dots progressively cluster higher for each standard deviation block; this is visual evidence that the IKDC changes tended to be larger than we would have predicted from baseline scores alone.