Isolated revision meniscal repair – failure rates, clinical outcome, and patient satisfaction

The menisci of the knee joint play an important role in load transmission, shock absorption, proprioception, cartilage lubrication, and joint stability [1]. Therefore, integrity of the menisci is crucial for long term knee function. For several decades, total or partial meniscectomy was the treatment of choice for symptomatic meniscus tears [2]. However, with the growing understanding of meniscal function and an increasing number of studies reporting suboptimal results after meniscectomy [3] meniscal repair has become widely accepted [4]. Compared to partial meniscectomy, meniscus repair has shown to result in better knee function, higher activity levels, less progression of osteoarthritis, and cost saving [5‐9]. However, the reoperation rate after meniscal repair is higher [5] and according to recent systematic reviews, a failure rate of approximately 11–23% must be excepted [10‐12]. With the increasing numbers of meniscal repairs performed during the last decade [13], the number of failed meniscus repairs will also increase. Until now, meniscectomy seems to be the preferred technique to address failed meniscus repairs [14‐17]. However, revision meniscal repair may provide better long-term outcomes than meniscectomy, but the results of this procedure remain underreported [18‐21]. It is therefore unclear if revision meniscal repair is worthwhile.

The purpose of this study was to evaluate the clinical outcome and failure rates of isolated revision meniscal repair in patients with re-tears or failed healing after previous meniscal repair in stable knee joints. We hypothesized that revision meniscal repair would demonstrate good clinical outcomes and an acceptable failure rate.

The most important findings of this study were that isolated revision meniscal repair results in good to excellent knee function, high level of sports participation, and high patient satisfaction in patients with re-tears or failed healing after previous isolated meniscal repair. The failure rate of 25% is slightly higher compared to isolated primary meniscal repair, but still acceptable. Therefore, revision meniscal repair seems to be a valuable treatment option in selected cases.

Integrity of the menisci is vital to maintain knee joint health, and the management of meniscal tears has evolved over the last decades [2]. Current evidence suggests that meniscus repair should be preferred over meniscectomy whenever possible in order to preserve as much meniscus tissue as possible [5‐8]. However, failure of primary meniscal repairs must be expected in approximately 11–23% of patients [10‐12]. Kurosaka et al. demonstrated that repaired menisci may tear again even after arthroscopically confirmed healing [22]. In their study, stable healing of the repaired meniscus was observed in 90 of 111 patients during second-look arthroscopies at a mean of 13 months after repair. Of the 90 patients with stable repairs, however, 13 patients sustained a re-tear of the meniscus, which was always located at the primary repair site. This finding corresponds well to the findings of our study. Most of our patients sustained a traumatic re-tear during sporting activities. Given the fact that most patients were able to perform sports after the primary repair and the relatively long time period between primary repair and revision repair, it can be hypothesized that healing occurred after primary meniscal repair. Similarly to the findings of Kurosaka et al., the re-tear in our series occurred at the primary repair site in all cases [22]. This may be attributed to the mechanically less stable scar tissue at the repair side observed in animal studies [23, 24].

With the increasing numbers of meniscal repairs observed during the last decade [13], failed repairs will become a more common problem. Therefore, recommendations for appropriate treatment of these cases will become more important. Similarly to primary meniscal repair, revision meniscal repair may provide better functional outcomes and less progression of osteoarthritis than meniscectomy [5‐8]. However, meniscectomy seems to be the preferred treatment option since results of revision meniscal repair remain underreported [14‐17]. To the best of our knowledge, only three studies have specifically analysed the results of revision meniscal repair so far [18‐20]. Despite differences in patient population, meniscal tear patterns, concomitant procedures, and follow-up period, the results of these studies are generally comparable to our results (Table 3): Voloshin et al. reported on a series of 18 repeat meniscal repairs performed over an 11-year period. After a mean follow-up of 7 years, the clinical success rate was 72% [20]. Imade et al. analyzed the results of revision meniscal repair in 15 patients. The success rate was 67%, and all failed revision repairs had degeneration of the meniscal tissue. The authors therefore concluded that revision meniscal repair should be considered in the setting of a re-torn meniscus without degenerative changes [18]. Krych et al. retrospectively investigated 34 patients at 2 to 17 years after revision meniscal repair. In 13 of these cases, concomitant ACL reconstruction was performed. The clinical success rate was 79%. Younger age was associated with an increased risk of revision repair failure, whereas tear zone, tear pattern, meniscal side, surgical technique, and combined ligament reconstruction were not significant predictors of failure [19]. The main difference between the present and the above stated studies is that we did not include patients who underwent concomitant reconstructive procedures, especially ACL reconstruction. It has been demonstrated that concomitant ACL reconstruction at the time of meniscal repair improves healing rates of the repaired meniscus [14]. We therefore excluded patients with concomitant procedures in order to reduce confounding factors. The present study is therefore the first to focus on isolated revision meniscal repair in stable knee joints.

Revision meniscal repair seems to have slightly higher failure rates compared to primary repairs. Nepple et al. [10] performed a systematic review of studies reporting the outcome of primary meniscal repair at a minimum of five years postoperatively. A total of 566 knees were included and the pooled rate of meniscal repair failure was 23%. Grant et al. [12] conducted a systematic review to compare the effectiveness of inside-out and all-inside repair techniques for isolated unstable peripheral longitudinal meniscal tears. The rate of clinical failure was 17% for inside-out repairs and 19% for all-inside repairs. In a more recent systematic review, Fillingham et al. [11] analyzed the results of inside-out and modern all-inside repairs for isolated meniscal tears. The overall clinical failure rate was 11% with no statistically significant differences between the two techniques. In the present study, the failure rate after isolated revision meniscal repair was 25%, which is slightly higher compared to the above reported failure rates after primary repairs. Furthermore, in 2 of the 3 failures, re-revision repair was performed, with clinically success in both patients. Therefore, the meniscus could be saved in a total of 92% of our patient cohort.

Despite a slightly higher failure rate, the clinical results observed in the present study are comparable to those reported after primary repairs. In the systematic review of Fillingham et al. [11], the mean Lysholm score was 89.0 and the mean Tegner score was 5.7. In the systematic review of Grant et al. [12], the Lysholm score was 90.2 for all-inside repairs and 87.8 for inside-out repairs. Corresponding Tegner scores were 5.5 and 5.6. In our study, the mean Lysholm Score was 95.2 and the mean Tegner score was 6.8. We therefore conclude that revision meniscal repair can achieve the same clinical results and same activity level as primary repair.

This study has several limitations. First, the study population was relatively small, which limits the overall validity of our results. However, revision meniscal repair is performed only infrequently and only patients without concomitant procedures were included. Therefore, our study cohort represents a relatively homogenous collective with regard to surgical treatment. Second, failure of revision meniscal repair was not evaluated by MRI or second-look arthroscopy. Therefore, the actual failure rate may be underestimated. Third, no statistical analysis was performed because preoperative scores were not available. However, the main intention of this study was to analyze the failure rate and clinical outcome at a minimum of 2 years after isolated revision meniscal repair. Fourth, no control group was analyzed. The present study cannot answer the question whether revision meniscal repair is superior compared to conservative treatment or partial meniscectomy. Further studies are necessary to evaluate whether revision meniscal repair can prevent or delay osteoarthritis.

In patients with re-tears or failed healing after previous isolated meniscal repair, revision meniscal repair results in good to excellent knee function, high level of sports participation, and high patient satisfaction. Clinical outcome scores and activity level after revision repair are not inferior compared to primary repairs. The failure rate is slightly higher compared to isolated primary meniscal repair, but still acceptable. Therefore, revision meniscal repair is worthwhile in selected cases in order to save as much meniscal tissue as possible.