This study compared patients who failed a cartilage restoration procedure and underwent ipsilateral knee arthroplasty with matched control subjects undergoing knee arthroplasty without prior cartilage restoration. Although patients with a failed cartilage procedure derived benefit from knee arthroplasty, their magnitude of improvement and final outcomes scores were lower than the matched control subjects. In this cohort, the cartilage patients also experienced little to no benefit from cartilage restoration, suggesting that unmeasured shared patient characteristics may play a role. This information can be used to counsel this difficult patient population on expected outcomes following arthroplasty procedures. Further research identifying characteristics of responders to treatment remains critical to refine clinical decision-making for this difficult patient group.
Key points
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When compared with matched control subjects, patients undergoing arthroplasty after prior cartilage/meniscal restoration have significantly less pain relief, lower functional outcomes, and less improvement following partial or total knee arthroplasty.
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Patients undergoing arthroplasty after prior cartilage/meniscal restoration have significantly less severe arthritic findings on radiographs as measured by the Kellegren and Lawrence grade compared with matched control subjects.
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In this study, patients who underwent arthroplasty after failed prior cartilage/meniscal restoration did not experience symptom relief after cartilage/meniscal restoration, which is atypical of the typical patient undergoing cartilage/meniscal restoration.
Introduction
Injuries to the articular cartilage of the knee are seen in up to 63% of arthroscopies. Articular cartilage defects do not reliably heal and can lead to degenerative joint disease, ultimately resulting in significant pain and disability. The optimal treatment strategy for these defects, one that provides the highest likelihood of a painless return to activity, remains unknown. In particular, young, active patients with symptomatic articular cartilage defects are challenging, because arthroplasty may lead to wear-related complications and a need for multiple revisions over an individual’s lifetime and hence articular cartilage and meniscal restoration procedures are being performed with increasing frequency.
Techniques including autologous chondrocyte implantation or variations thereof ( Fig. 1 ), osteochondral autograft transfer, osteochondral allograft transplantation, and meniscus allograft transplantation (MAT) provide alternatives to arthroplasty to help improve function and reduce pain. In some settings, both cartilage restoration and arthroplasty may be viable surgical alternatives for these patients. Given that patients’ status-post cartilage restoration can be revised to arthroplasty and arthroplasty cannot be revised back to native cartilage, cartilage restoration has been advocated as a “conservative” surgical approach that does not “burn any bridges.” If cartilage restoration fails, patients may progress to knee arthroplasty, including total knee arthroplasty (TKA) and unicompartmental knee arthroplasty (UKA), as their definitive pain-relieving surgical solution. It remains unknown whether the outcome of knee arthroplasty after cartilage restoration is equivalent to the outcome had the knee arthroplasty been performed primarily.
To date, no data are available regarding clinical outcomes following conversion of a joint preservation procedure, such as cartilage/meniscal restoration, to TKA. Such information would be especially important with respect to preoperative counseling for patients related to the outcomes following arthroplasty procedures. Therefore, the purpose of this study was to compare the clinical outcomes of patients with a history of cartilage or meniscal restorative procedures with age-, sex-, and procedure-matched control patients undergoing primary TKA or UKA. The authors hypothesized that outcomes following primary TKA will be equivalent to those with TKA following cartilage and/or meniscus restoration.
Introduction
Injuries to the articular cartilage of the knee are seen in up to 63% of arthroscopies. Articular cartilage defects do not reliably heal and can lead to degenerative joint disease, ultimately resulting in significant pain and disability. The optimal treatment strategy for these defects, one that provides the highest likelihood of a painless return to activity, remains unknown. In particular, young, active patients with symptomatic articular cartilage defects are challenging, because arthroplasty may lead to wear-related complications and a need for multiple revisions over an individual’s lifetime and hence articular cartilage and meniscal restoration procedures are being performed with increasing frequency.
Techniques including autologous chondrocyte implantation or variations thereof ( Fig. 1 ), osteochondral autograft transfer, osteochondral allograft transplantation, and meniscus allograft transplantation (MAT) provide alternatives to arthroplasty to help improve function and reduce pain. In some settings, both cartilage restoration and arthroplasty may be viable surgical alternatives for these patients. Given that patients’ status-post cartilage restoration can be revised to arthroplasty and arthroplasty cannot be revised back to native cartilage, cartilage restoration has been advocated as a “conservative” surgical approach that does not “burn any bridges.” If cartilage restoration fails, patients may progress to knee arthroplasty, including total knee arthroplasty (TKA) and unicompartmental knee arthroplasty (UKA), as their definitive pain-relieving surgical solution. It remains unknown whether the outcome of knee arthroplasty after cartilage restoration is equivalent to the outcome had the knee arthroplasty been performed primarily.
To date, no data are available regarding clinical outcomes following conversion of a joint preservation procedure, such as cartilage/meniscal restoration, to TKA. Such information would be especially important with respect to preoperative counseling for patients related to the outcomes following arthroplasty procedures. Therefore, the purpose of this study was to compare the clinical outcomes of patients with a history of cartilage or meniscal restorative procedures with age-, sex-, and procedure-matched control patients undergoing primary TKA or UKA. The authors hypothesized that outcomes following primary TKA will be equivalent to those with TKA following cartilage and/or meniscus restoration.
Methods
This study underwent approval by our university’s institutional review board. A retrospective review of prospectively collected data on consecutive patients who underwent cartilage restoration by a single surgeon and subsequently progressed to arthroplasty was performed. Inclusion criteria included patients with a history of a prior open or arthroscopic cartilage and/or meniscal restoration procedure and subsequent ipsilateral UKA or TKA. The cartilage/meniscal restoration procedures included osteochondral autograft transfer, osteochondral allograft transplantation, and/or MAT of the same condyle and joint. All cartilage patients were matched with control patients based on sex, age ± 5 years, body mass index (BMI) ± 5, smoking status, and arthroplasty type. All patients in both the cartilage and the control groups were followed for a minimum of 2 years. Exclusion criteria in the cartilage group included patients whose cartilage/meniscal procedure was complicated by infection or chondrolysis as a complication of the index cartilage procedure and patients undergoing revision cartilage/meniscal restoration.
In the cartilage group, indications for cartilage/meniscal restoration versus primary knee arthroplasty included symptomatic, unipolar, full-thickness articular cartilage lesions and/or symptomatic meniscal deficiency not amenable to repair, in patients without diffuse arthritic changes in the affected compartment. Patients were also required to be ligamentously stable (or correctable) with neutral (or correctable) coronal plane alignment. In the cartilage group and the control groups, indications for arthroplasty were symptomatic medial or lateral tibiofemoral pain (UKA) or diffuse symptomatic bicompartmental or tricompartmental degenerative changes (TKA), unresponsive to prior treatment. In addition, indications for UKA included intact cruciate ligament status, lack of patellofemoral arthritis greater than grade III or IV on radiographs, lack of coronal plane deformity greater than 5°, and lack of knee flexion contracture greater than 5°. All patients in both groups underwent preoperative physical therapy.
Data collected for all patients included age, sex, laterality, comorbidities, preoperative and final follow-up Knee Society Score (KSS), Quality of Life Short-Form-12 score, Hospital for Special Surgery scores, and range of motion (ROM). Prearthroplasty radiographs were graded according to the Kellgren and Lawrence scale. In addition, the cartilage patients were assessed pre–cartilage procedure and post–cartilage procedure (prearthroplasty) with the following outcomes assessments: Tegner, Lysholm, International Knee Documentation Committee (IKDC), and Knee Injury and Osteoarthritis Outcome Score (KOOS) for pain. The control patients were not analyzed with the Tegner, Lysholm, IKDC, or KOOS scores because these outcomes instruments are not used in the preoperative or postoperative assessment of patients undergoing primary knee arthroplasty for osteoarthritis.
Statistical Analysis
All analyses were performed in Excel X (Microsoft Inc, Redmond, WA) and SPSS version 21 (IBM Inc, Armonk, NY). Categorical data were compared between study and control groups using chi-square and Fisher exact tests as appropriate. For continuous variables Komolgorov-Smirnov testing was performed. To compare between study and control groups Student t tests and Mann-Whitney U tests were performed as appropriate. Within study and control groups preoperative and postoperative data were compared using paired Student t tests and related-samples Wilcoxon signed rank tests as appropriate. Because a limited number of patients are available who have undergone both cartilage restoration and knee arthroplasty on the same knee, all eligible patients were included and no a priori power analysis was conducted. A post hoc power analysis was performed; based on the means and standard deviations for the difference in preoperative and postoperative KSS the effect size was 1.67. With this study size the study’s power was found to be 98%.
Results
A total of 26 patients were included, with 13 patients (eight TKA and five UKA) in each group. The average clinical follow-up was 3.7 years (range, 2.0–7.2 years). There were no significant differences in age, sex, BMI, smoking status, worker’s compensation status, preoperative physical therapy participation, preoperative ROM, postoperative ROM, or preoperative KSS scores between groups ( P >.05 in all cases), suggesting adequate matching ( Table 1 ). There were no intraoperative or postoperative complications, and there were no differences in tourniquet time between the cartilage and control groups (average of 82 vs 90 minutes, respectively; P = .08).
| Control Group | Cartilage Group | P Value | |
|---|---|---|---|
| Age, y | 44 ± 5 | 42 ± 6 | .567 |
| BMI | 32 ± 7 | 31 ± 6 | .576 |
| Length of follow-up, y | 3.3 ± 1.5 | 4 ± 1.7 | .239 |
| Time from cartilage restoration to arthroplasty, y | N/A | 2.6 ± 1.8 | N/A |
| Female, % | 46 | 46 | 1.000 |
| Smokers, % | 15 | 15 | 1.000 |
| Worker’s compensation, % | 23 | 38 | .673 |
| Arthroplasty type | 5 UKA, 8 TKA | 5 UKA, 8 TKA | N/A |
| Tourniquet time, min | 90 ± 13 | 81 ± 10 | .08 |
Before arthroplasty, the patients in the cartilage group underwent the following cartilage/meniscal restoration procedures: medial femoral condyle osteochondral allograft (n = 8), medial femoral condyle osteochondral allograft with corrective osteotomy (n = 1), MAT with anterior cruciate ligament reconstruction (n = 1), MAT with corrective osteotomy (n = 2), and patella osteochondral allograft with corrective osteotomy (n = 1). For the 10 patients with focal chondral lesions, the average defect size was 331 ± 204 mm 2 (range, 100–625 mm 2 ). Before cartilage/meniscal restoration, patients had undergone an average 2 ± 2 prior surgeries (range, 1–7 surgeries) on the ipsilateral knee, including diagnostic arthroscopy, arthroscopic chondroplasty, arthroscopic partial meniscectomy, medial collateral ligament reconstruction, anterior cruciate ligament reconstruction, tibial plateau open reduction internal fixation, and medial patellofemoral ligament imbrication. Following cartilage/meniscal restoration, all patients underwent a standardized rehabilitation protocol at the direction of the senior author, including 6 to 8 weeks of protected weight-bearing, physical therapy, and return to full activities by 4 to 6 months following surgery. The duration of time between the cartilage/meniscal restoration procedure and the arthroplasty averaged 2.6 ± 1.8 years (range, 7.8 months to 7.7 years).
In the cartilage group, there were no significant differences in precartilage scores to postcartilage (prearthroplasty) scores for any of the outcomes assessments. Specifically, there were no postcartilage restoration improvements in the Tegner (2.4 ± 2.4–2.3 ± 0.8; P = .729), Lysholm (30.8 ± 17.1–38.2 ± 20.0; P = .474), IKDC (26.4 ± 10.3–33.0 ± 10.3; P = .847), or KOOS-pain (41.7 ± 19.4–59.0 ± 19.9; P = .672) scores.
Patients in the cartilage group had a significantly lower prearthroplasty (postcartilage) Kellgren and Lawrence grade (average, 2.6 ± 0.9) compared with matched control subjects (average, 3.7 ± 0.5; P = .004).
Patients in the cartilage group had significantly lower postoperative KSS scores (78 ± 13 vs 91 ± 5; P = .005) ( Table 2 ) and experienced significantly less improvement in KSS scores (30 ± 10 vs 46 ± 10; P <.001). Two patients (15%) in the cartilage group required revision TKA at 1.9 years (for pain) and 4.7 years (for infection) following the index TKA. There were no reoperations in the control group.
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