Meniscal allograft transplantation (MAT) may offer an attractive alternative to restore the normal biomechanical structure of knees. The mean early failure rate (≤2 years) of MAT is approximately 10%.1–3 A successful outcome of MAT depends on the ligamentous stability of knee, limb alignment, graft types, and graft fixation methods.4,5 Graft fixations include the meniscal horns and the peripheral rim. Techniques for fixation of the peripheral rim include sutures or a meniscal repair device such as FasT-Fix (Smith & Nephew Inc, Andover, MA, USA). Here we present an unusual case of early graft failure using FasT-Fix sutured to the peripheral rim of the graft.
A 28-year-old male was referred to our center complaining of recurrent pain, swelling, and instability for 3 months after accidentally spraining his right knee. His medical history included injury of the medial meniscus of the right knee 3 years ago. A total open meniscectomy was performed by a local hospital. On physical examination, the right knee presented with mild effusion and tenderness on the medial joint line, marked anterior laxity (positive Lachman and pivot-shift test), the end-point was soft, and the side-to-side difference was 5 mm as measured by KT-1000 (MeDmetric Inc, San Diego, USA). Magnetic resonance imaging (MRI) demonstrated increased signal intensity of the anterior cruciate ligament (ACL) on T2-weighted images, and also indicated an absence of the medial meniscal tissue (Figure 1A and 1B).
It was decided to perform a medial MAT combined with single-bundle ACL reconstruction arthroscopically. During the surgery, arthroscopic findings showed grade II cartilage damage on the medial compartment of the femur and tibia according to Outerbridge classification (Figure 1C). Debridement was performed over the surface of the damaged cartilage.
The graft was deep-frozen (-80°C) and preserved with low-dose irradiation (1.5 M rads) for secondary sterilization. The graft size was 29 mm×49 mm (measured preoperatively by computed tomography).3 The meniscal allograft was transplanted using a double bone plug technique to fix the anterior and posterior horn. The anatomic insertional site of the anterior and posterior horn was visualized with the arthroscope introduced from the high anteromedial portal and the posteromedial portal. The middle and posterior portions of the peripheral rim of the graft were sutured to the capsule using FasT-Fix (1-0 non-absorbable USP braided polyester suture, Smith & Nephew Inc, Figure 1D and E). Six stitches were used, including three vertical mattress sutures and one horizontal mattress suture on the superior surface, together with two vertical mattress sutures on the inferior surface. Three additional vertical mattress sutures were placed at the anterior portion using a standard outside-in meniscal repair technique (2-0 Ethibond, Ethicon Inc, Somerville, NJ, USA).
Postoperatively, the patient participated in a standardized rehabilitation program.3 The knee was braced in extension for 4 weeks. Knee flexion did not exceed 90° during the first 4 weeks postoperatively. The patient was not allowed to squat for 3 months and was restricted to partial weight bearing until 6 weeks postoperatively.
At 3 months after surgery, the patient presented with slight limitation of the knee extension. Physical examination showed a 10° loss of passive knee extension, obvious tenderness on the medial joint line, no anterior laxity (negative Lachman and pivot-shift test), the end-point was firm, and the side-to-side difference was 0 mm measured by KT-1000. MRI revealed a low signal intensity ACL graft on T2-weighted images, and there was an obvious bucket-handle tear of the medial meniscus graft and the torn fragment was displaced into the intercondylar notch (Figure 1F and 1G). Arthroscopy showed that the ACL graft was in continuity. A bucket-handle tear of the medial meniscal graft was observed at the peripheral rim and was displaced within the intercondylar notch. All FasT-Fix sutures were disrupted (Figure 1H and 1I). It was decided to completely remove the graft, and performed a revision medial MAT. A double bone plug technique was chosen as previously described for fixation of the anterior and posterior horn. FasT-Fix was no longer used. The middle and posterior portion of the peripheral rim of the graft was sutured to the capsule using a standard inside-out meniscal repair technique (Figure 1J and 1K), with eight vertical mattress sutures (2-0 non-absorbable USP braided polyester suture, Linvetec Inc, Largo, FL USA). Four vertical mattress sutures were placed at the anterior portion with a standard outside-in meniscal repair technique using 2-0 Ethibond.
The post-operative rehabilitation protocol was the same as described previously. The patient was followed-up 12 months after revision of the medial MAT. On physical examination, there was no tenderness on the medial joint line, no anterior laxity (negative Lachman and pivot-shift test), the end-point was firm, and side-to-side differences were 2 mm measured by KT-1000. MRI demonstrated a low signal intensity ACL graft and a well-positioned medial meniscal graft, which showed no signs of degenerative changes or tears (Figure 1L and 1M). A second look arthroscopy (for the internal fixation removal) was performed. The ACL graft appeared normal with complete synovial coverage. The meniscal graft was intact and stable, the peripheral rim was totally healed with the capsule, and no tears were found (Figure 1N).
Most surgeons favor an all-inside arthroscopic meniscal repair device, such as FasT-Fix, because of the low complication rate, short surgical time and ease to use.6 However, some biomechanical studies have failed to find any statistical difference between FasT-Fix and inside-out suture repair.6 While the vertical inside-out suture technique is considered the gold standard for meniscus repair, there is no gold standard for peripheral rim fixation of MAT. Several factors influence the likelihood of a successful outcome, such as ligamentous stability of knee, limb alignment, graft types and size, and postoperative rehabilitation protocol.4,5
In this case, the influence factors are almost the same between the first MAT and revision except peripheral rim fixation of the middle and posterior portion of the graft. Rijk4 suggested that peripheral capsular fixation was a prerequisite for healing and vascularization of the graft. Absence of peripheral healing and revascularization induces cell death and matrix disorganization, which can result in MAT fixation failure. One reason for failure in our patient may have included insufficient fixation strength. The length of the peripheral rim fixation of meniscal graft in MAT is much longer and suture tension is also higher than in regular meniscus tears during the early postoperative period, so the fixation strength of FasT-Fix may not be sufficient to withstand this. However, to date there are no biomechanical studies that have investigated using meniscal repair device in MAT. Tissue reapproximation with Fast-Fix is not as good as that achieved using the inside-out technique and that may be another reason for early failure of the graft in our patient.
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4. Rijk PC. Meniscal allograft transplantation—part: background, results, graft selection and preservation, and surgical considerations. Arthroscopy 2004; 20: 728-743.
5. Jung KA, Lee SC, Hwang SH. “Suture-induced tear” after human meniscal allograft transplantation. Knee 2010; 17: 88-91.
6. Borden P, Nyland J, Caborn DN, Pienkowski D. Biomechanical comparison of the FasT-Fix meniscal repair suture system with vertical mattress sutures and meniscus arrows. Am J Sports Med 2003; 31: 374-378.