Treatment of intrasubstance meniscal lesions: a randomized prospective study of four different methods

Introduction Intrasubstance meniscal lesions are incomplete horizontal lesions without connection to the surface or the bed of the meniscus [6, 26]. They present a prominent linear high-in- tensity signal on the magnetic resonance image (MRI) [6, 26] (Fig.1). The grade 2 signal intensity can occur with- out compartment pain or clinical significance. The signal intensity reflects myxoid degeneration with subsequent disintegration of fibrocartilage (chondrocyte destruction) [20]. The grade 2 signal can also be caused by synovial fluid in a horizontal lesion with pain in the joint line, es- pecially after mechanical stress and shearing forces. Dil- lon et al. [13] have suggested that a more extensive intra- substance signal would have a higher significance for rep- resenting a tear. Symptomatic intrasubstance lesions are painful. The meniscus itself [9] and the perimeniscal tis- sue [7] have a multitude of free nerve endings of type IVa. These nociceptors are highly sensitive to the injured tis- sue. Most intrasubstance meniscal lesions occur in the red- white zone and extend to the white-white central avascu- lar third of the meniscus [1]. The diminished vascular blood supply in these zones may explain why both degen- erative changes and incomplete horizontal lesions can oc- Abstract This study examined the effect of four different methods for treating intrasubstance meniscal le- sions. Forty patients (21 men, 19 women; age 30.4 years, range 16–50) with an isolated and sympto- matic painful horizontal grade 2 meniscal lesion on the medial side (documented with MRI) were in- cluded. Patients were randomly as- signed by the birth date to one of four treatment groups: group A, con- servative therapy (n = 12); group B, arthroscopic suture repair with ac- cess channels (n = 10); group C, arthroscopic minimal central resec- tion, intrameniscal fibrin clot and su- ture repair (n = 7); and group D, arthroscopic partial meniscectomy (n = 11). The average length of fol- low-up was 26.5 months (range 12–38 months). Follow-up evalua- tion consisted of clinical examination with the findings recorded according to the IKDC protocol, radiographs, and control MRI. Group A had 75% normal or nearly normal final evalu- ation at follow-up, group B 90%, group C 43%, and group D 100% normal or nearly normal at follow- up. These short-term results indicate that intrasubstance meniscal lesions can be treated best by performing partial meniscectomy. To preserve the important function of the menis- cus, arthroscopic suture repair with access channels might give even bet- ter medium- to long-term results. Conservative treatment is often not satisfactory. Additionally, our find- ings show that MRI examinations are not superior to accurate clinical ex- aminations. Key words Intrasubstance meniscal lesions · Arthroscopy · Treatment of meniscal lesions · Magnetic resonance imaging KNEE Knee Surg, Sports Traumatol, Arthrosc (2000) 8 :104–108 © Springer-Verlag 2000 Roland M. Biedert Treatment of intrasubstance meniscal lesions: a randomized prospective study of four different methods Received: 17 May 1999 Accepted: 15 December 1999 R. M. Biedert Sports Traumatology and Orthopedics, Institute of Sport Sciences, 2532 Magglingen, Switzerland e-mail: [email protected] Tel.: +41-32-3276304 Fax: +41-32-3276405 cur. Experimental and clinical observations have shown that avascular lesions are incapable of healing, thereby providing the rationale for partial meniscectomy [2, 3, 11, 16, 18]. In contrast, McLaughlin and Noyes [21] and Rub- man et al. [25] recommend repair of meniscal tears (com- plete or incomplete) that also extend into the avascular re- gion. No investigators, to our knowledge, have evaluated the treatment of horizontal grade 2 meniscal lesions. The pur- pose of the present study was to describe our experience with four different methods for treating isolated sympto- matic medial intrasubstance meniscal lesions. Patients and methods Between April 1994 and August 1996, 40 patients (21 men, 19 women; age 30.4 years, range 16–50) with an isolated and painful medial intrasubstance meniscal lesion were included in this prospective study. All patients had clinical symptoms of a menis- cal tear and a MRI linear high grade 2 signal intensity in the me- dial meniscus. The patients were randomly assigned by birthdate to one of the four treatment groups. Therefore the number in the groups varies. Groups and treatment All patients were treated by the same orthopedic surgeon. – Group A: conservative treatment (n = 12). These patients were treated by anti-inflammatory medication and local physical ther- apy (ultrasound). – Group B: arthroscopic suture repair with access channels (n = 10). An 18-gauge spinal needle was used to puncture the meniscus sev- eral times under arthroscopic control from outside in, extending from the capsule to the inner rim without perforating the surfaces. Then, using a standardized inside-out endoscopic technique, the surgeon repaired the meniscus with six to eight (half from superior and half from inferior) 2/0 Vicryl sutures (Fig.2). – Group C: arthroscopic minimal central resection, fibrin clot, su- ture repair (n = 7). The central part of the meniscus was minimally resected and the intrasubstance lesion palpated with a probe. Then the intrasubstance tissue was débrided with a full radius synovial resector from inside. The space between the superior and inferior surface was filled with a fibrin clot (Tissucol, Immuno, Vienna, Austria) and the lesion was repaired with six to eight 2/0 Vicryl su- tures (Fig.3). – Group D: arthroscopic partial meniscectomy (n = 11). The ratio- nal partial meniscectomy was performed by using a full radius re- sector and basket forceps. The outer rim with the horizontal fibers was preserved (Fig.4). Rehabilitation – Group A: The patients could continue with their normal daily and sport activity level during the whole time. – Groups B, C: Immediate knee motion was started the first day postoperatively to achieve 10–80° of knee flexion as soon as possi- ble. Full range of motion was allowed 6 weeks after repair. Crutches were used for the first 6 weeks postoperatively to prevent excessive stress (maximal 20 kg weightbearing). Patients were restricted from sports with cutting or jumping maneuvers for 4 months. – Group D: Crutches with 20 kg weightbearing were used for the first 2 weeks postoperatively. The range of motion was not limited. Full sport activities were allowed when the patient was free of pain and had no effusion within the joint (3–4 weeks postoperatively). Follow-up evaluation The average length of follow-up was 26.5 months (range 12–38 months). The follow-up evaluation consisted of clinical examina- tion with the findings recorded according to the International Knee Documentation Committee form, full weightbearing radiography in extension, and control MRI. All complications and postopera- tive problems were recorded. Statistical methods Because of the small sample size (and therefore small expected frequencies in the cross-tabulation), Fisher’s exact test was used to describe differences between groups of treatment. All analyses were performed with the Statistical Package for Social Science. The Significance level for Fisher’s exact test was 0.05. The statis- tical analysis was performed one time with three categories – (a) normal, (b) nearly normal, (c) abnormal and severely abnormal; and one time with four categories – (a) normal, (b) nearly normal, (c) abnormal, and (d) severely abnormal. Results The final evaluation of the clinical and radiographic find- ings of the 40 patients is summarized in Table 1. Statistical analysis using the three categories showed highly signifi- cant differences between groups D and A (P = 0.006) and between groups D and C (P = 0.003). Analysis using the four categories showed the differences between Groups D and C to be significant (P = 0.01) but not to the extent as in the analysis with three categories. No significant differ- ences were found between the other treatment groups. 105 Fig.1 Horizontal intrasubstance meniscal lesion on the medial side (arrow) Ten of the 40 patients had postoperative problems or complications. In group A two patients still suffered pain during light activity. One of these needed a partial menis- cectomy, and the other had a suture repair with access channels after the follow-up control. In group B one pa- tient complained of abnormal function and consistent pain. The patient also had saphenous nerve paresthesia. Subsequently a partial meniscectomy and decompression of the nerve were performed. In group C six patients had problems with pain, and one of the six had saphenous nerve paresthesia. A secondary partial meniscectomy was performed in two patients (one with additional nerve revi- sion) after the follow-up examination. Only one patient had a normal knee with the minimal central resection, fib- rin clot, and suture repair. In group D one patient did not tolerate strenuous activity and felt some pain. No revision surgery was necessary in this group. MRI (T1- and T2-weighted) during follow-up exami- nations showed no correlations in the different groups. 106 Fig.2 Arthroscopic suture repair Fig.3 Arthroscopic suture repair after resection of the central part of the meniscus and application of a fibrin clot Fig.4 Situation after arthroscopic partial meniscectomy Fig.5 Unstable central intrasubstance meniscal lesion in the white-white zone 2 3 4 5 Higher signal intensities were present or not in conserva- tively treated and in operated patients, in operated patients with symptoms, and patients with pain-free knees. Full weight-bearing radiography revealed no significant ab- normalities. Discussion Partial meniscectomy, according to our findings in the present study, offers the best short-term results for pa- tients with intrasubstance meniscal lesions. None of the patients treated with this technique needed revision sur- gery during the follow-up time. The best indications for partial meniscectomy are very central unstable lesions in the white-white zone (Fig. 5). Although Rubman et al. [25] recommend repair of meniscal tears that extend into the avascular central zone in young patients and highly competitive athletes, we have a different opinion at our Institute. We have found that treating central avascular le- sions by partial meniscectomy has advantages, especially in the knees of top-level athletes. These athletes wish short rehabilitation time (instead of 4–6 months) [25], no secondary intervention, lowest risk of complications (nerve paresthesia, restriction of range of motion, limita- tion of meniscus mobility), and the same or better activity level than before injury. With rational partial meniscec- tomy, the outer rim (which is required to resist normal hoop stresses) can be preserved, according to Mooney and Rosenberg [22]. Athletes with intact cartilage and age be- low 30 years at index operation have only an 8% inci- dence of late arthrosis (12–15 year follow-up) after partial meniscectomy presenting 85–95% good clinical results [19]. An additional advantage of early minimal partial meniscectomy is that these small grade 2 lesions are pre- vented from turning into larger grade 3 lesions that would require more substantial resections of the meniscus into the red-red zone [2, 3, 11, 16, 18]. Indications for partial meniscectomy are degenerative tears or tears larger than 6 mm from the periphery [22], tears into the avascular in- ner third of the meniscus [23], and a central one-third fragmented meniscus [21]. However, partial meniscectomy significantly increases contact pressures. It does not appear always to be a benign procedure [4]. The increased risk of tibiofemoral joint arthrosis after meniscectomy has been demonstrated in several long-term clinical studies, especially in patients with preexisting chondral damage [19, 25]. For DeHaven [12], good indications for suture repair are peripheral or nearly peripheral meniscus tears within 2 mm of the meniscosynovial junction. According to Beaufils [5], suit- able tears for arthroscopic repair are 4 mm from the pe- riphery. A 2.5-mm tear from the periphery should be re- paired by performing an arthrotomy. Tears less than 2 mm from the periphery heal better than those 4 mm from it. Beaufils also states that meniscal repair must be in the red-red zone. In children and adolescents, meniscal tears within 50–60% of the periphery can be repaired because the middle third of the meniscus is more vascular than in adults [10]. Arthroscopic suture repair with access channels from outside-in lead to normal or nearly normal results in 90% of our patients and might yield even better medium- to long-term results than partial meniscectomy. This proce- dure preserves the important functions of the meniscus. To extend the level of repair in the critical avascular areas, various techniques that provide vascularity to these white- white tears have been described in the literature. These techniques include vascular access channels [2, 15, 28], fibrin clots [8, 24], and synovial abrasion [17]. Fox et al. [15] treated symptomatic incomplete meniscal tears by stimulation of vascular channels (trephination) and re- ported good and excellent overall results in 90% of their cases, but all the tears were considered stable (the portion of the meniscus central to the tear could not be displaced by more than 3 mm) at the time of arthroscopy. The im- portant benefit of access channels with injury within the peripheral vascular zone seems to be the formation of a fibrin clot that is rich in inflammatory cells. Vessels from the perimeniscal capillary plexus proliferate through this fibrin “scaffold,” as described by Ulrich and Arnoczky [27]. The lesion is filled with a scar tissue that glues the wound edges together [27]. We suggest that this healing process is also possible in intrasubstance meniscal le- sions. Our results support this concept. Preoperative MRI findings were correlated in all pa- tients with the perioperative situation. We found no grade 3 lesions. The MRI was reliable for planning surgery in combination with the clinical examination. MRI was included in the follow-up evaluation of pa- tients with conservative treatment and those with suture repair with access channels. Normal and/or abnormal MRI signals were present in cases of asymptomatic and symp- tomatic menisci. Higher MRI signals often persist in re- paired menisci and do not properly allow the evaluation of meniscal healing. In our opinion, the careful clinical ex- amination, performed by an experienced orthopedic sur- geon is superior to the MRI evaluation. On MRI evalua- tions Eggli et al. [14] found normal anatomical position- ing of the sutured meniscus without any significant gap around the original tear in patients with failed meniscus 107 Table 1 International Knee Documentation Committee evalua- tion (percentages) Group A Group B Group C Group D (n = 12) (n = 10) (n = 7) (n = 11) Normal 25 60 14 91 Nearly normal 50 30 29 9 Abnormal 25 10 43 0 Severely abnormal 0 0 14 0 108 repairs. They also concluded that MRI does not provide definitive information concerning the healing properties of the repaired menisci. In conclusion, two important questions must be raised when the surgeon is treating intrasubstance meniscal le- sions arthroscopically: (a) Is the lesion stable? If it is un- stable (the portion of the meniscus central to the lesion can be displaced by more than 3 mm), suture repair is nec- essary. If it is stable, trephination to create vascular access channels into the lesion in the avascular portion is proba- bly sufficient. (b) Is the lesion in the red-red (vascular), the red-white (less functioning vessels), or the white- white (avascular) zone? If the lesion is in the red-white zone, access channels are needed to improve healing of these lesions. Our recommendations for the overall treatment of in- trasubstance meniscal lesions can be summarized as fol- lows: – Diagnostic: local anesthesia from outside into the meniscus – Conservative: fibrin clot/blood from outside by injec- tion Local anesthesia with trephination of the meniscus – Operative: – Stable lesion: red-red zone: nothing Red-white: access channels/trephination White-white zone: minimal partial meniscectomy – Unstable lesion: in the periphery and red-white zone: suture repair and access channels Central portion: partial meniscectomy 1.Arnoczky SP (1992) Gross and vascu- lar anatomy of the meniscus and its role in meniscal healing, regeneration, and remodeling. 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