Lateral Meniscal Transplantation Research Articles

Bone bridge technique for lateral meniscal allograft transplantation: no difference in clinical outcome compared to the soft tissue technique.

There is considerable debate regarding the optimal method of fixation for lateral meniscus allograft transplantation (MAT), with bone bridge techniques technically harder but allowing maintenance of root attachments, while soft tissue techniques are potentially more challenging for healing. The aim of this study was to compare the clinical results of the bone bridge and soft tissue techniques for lateral MAT in terms of failure, re-operation rate, complications and patient reported outcomes. Retrospective analysis of prospectively collected data for patients undergoing primary lateral MAT with a minimum of 12-month follow-up. Patients following surgery utilising the bone bridge technique (BB) were compared with historical control patients who underwent MAT with the soft tissue technique (ST). Outcome was assessed by failure rate, defined as removal or revision of the meniscus transplant, survivorship by Kaplan-Meir analysis, re-operation rates, and other adverse event. Patient-reported outcome measures (PROMs) were compared using data at the 2-year point or 1year if not reached 2years. One-hundred and twelve patients following lateral meniscal transplants were included, 31 in the BB group and 81 in the ST historical control group, with no differences in demographics between both groups. Median follow-up for the BB group was 18 (12-43) months compared to 46 (15-62) months for the ST group. There were 3 failures (9.6%) in the BB group v 2 (2.4%) in the ST group (n.s.) with a mean time to failure of 9months in both groups. 9 patients (29%) required a re-operation (all cause) in the BB group v 24 patients (29.6%) in the ST group (n.s). There was no difference in complications between both groups. There was significant improvement (p < 0.0001) in all PROMs (Tegner, IKDC, KOOS and Lysholm) between baseline and 2-year follow-up for both groups but no between-group differences. Lateral MAT has a high success rate for symptomatic meniscal deficiency with significant benefits irrespective of the fixation technique. There is no advantage in performing the more technically demanding BB technique over ST fixation. Level 2.

Correlation Between Anatomic Landmarks and Bony Trough Position in Lateral Meniscal Allograft Transplant.

Background:Determining the rotational axis of the bony trough during lateral meniscal allograft transplant (MAT) is difficult. The use of anatomic landmarks may help a surgeon determine the rotational alignment of the graft during the procedure.Purpose:To investigate the association between the knee's anatomic landmarks and the position of the bony trough to prevent extrusion after lateral MAT.Study Design:Cross-sectional study; Level of evidence, 3.Methods:Enrolled were 44 patients who underwent lateral MAT between July 2000 and February 2011. The patients’ mean age at the time of surgery was 30.8 years. Extrusion was measured on magnetic resonance imaging (MRI) scans at a mean of 3.6 months postoperatively, and patients were divided into an extrusion group (n = 15) and a no-extrusion group (n = 29). Three coronal MRI scans from each patient were selected, each from the region at the level of the tibial tuberosity (TT), the anterior bony trough, and the posterior bony trough. We measured the distance between the center of the anterior bony trough and the center of the TT (the TT distance) and the distance between the center of the posterior bony trough and the medial border of the lateral femoral condyle (LFC) (the LFC distance).Results:The mean center of the anterior bony trough was in a more medial position relative to the center of the TT in the no-extrusion group (–2.9 ± 4.8 mm) compared with the extrusion group (1.3 ± 4.9 mm; P = .010). The mean center of the posterior bony trough was in a more medial position relative to the medial border of the LFC in the no-extrusion group (–1.7 ± 3.9 mm) compared with the extrusion group (1.0 ± 3.2 mm; P = .027). Both TT distance and LFC distance were significantly correlated with extrusion (P = .005 and .025, respectively). The cutoff value was –0.24 mm for the anterior bony trough and –0.58 mm for the posterior bony trough (negative values indicate that the trough was medial to the respective landmarks).Conclusion:To prevent extrusion of the allograft, the center of the anterior bony trough needs to be aligned with the center of the TT, and the center of the posterior bony trough needs to be aligned with the medial border of the LFC.

Lateral Capsular Stabilization in Lateral Meniscal Allograft Transplantation.

Background:Stabilization of the lateral capsule to the tibial plateau may decrease midbody extrusion after lateral meniscal allograft transplantation (MAT). However, there is a paucity of literature reporting on postoperative magnetic resonance imaging (MRI) findings after lateral capsular stabilization (LCS) at the time of lateral MAT.Purpose/Hypothesis:The purpose was to describe MRI findings after LCS and compare postoperative extrusion between isolated lateral MAT and lateral MAT with LCS. It was hypothesized that allograft extrusion would be reduced after MAT with LCS but that the stabilized capsule would increase the risk of tears to the capsule or allograft.Study Design:Cohort study; Level of evidence, 3.Methods:Included were patients who underwent lateral MAT with 6-month follow-up MRI. Concomitant LCS was performed for patients with redundant lateral capsule displaced from the lateral tibial plateau as evident on coronal MRI or arthroscopic examination (MAT+LCS group); otherwise, patients underwent MAT only (isolated MAT group). The Lysholm score, Tegner score, and lateral joint space on radiographs were compared between the 2 groups at 2 years postoperatively, and the stabilized lateral capsule and allograft were evaluated using 6-month follow-up MRI. Extrusion, rotation, and position of the allograft bridge were compared between the 2 groups. Regression analysis was performed to identify factors predictive of degree of extrusion.Results:There were 10 patients in the MAT+LCS group and 13 patients in the isolated MAT group. No significant differences were found between groups in preoperative patient characteristics or postoperative Lysholm score, Tegner score, lateral joint space, or MRI parameters. Postoperative extrusion was not related to obliquity angle, position of the bony bridge, or presence of LCS. In the MAT+LCS group, 1 patient showed a tear of the lateral capsule and a radial tear of the allograft, and 3 patients had a meniscocapsular separation at the midbody of the allograft. In the isolated MAT group, 1 patient had a peripheral tear at the midbody, but there was no tear of the allograft in the other patients.Conclusion:LCS did not decrease extrusion of lateral meniscal transplantation, but it can lead to increased risk for graft or capsule tear.

Radiographic Methods Are as Accurate as Magnetic Resonance Imaging for Graft Sizing Before Lateral Meniscal Transplantation

Background: Accurate allograft matching is deemed critical for meniscal transplantation; thus, precise measurements are essential to correctly calculate meniscal size. Several methods for meniscal sizing have been described, but there remains a discussion on which is the most accurate for the lateral meniscus. Purpose: To compare the accuracy of radiographic, anthropometric, and magnetic resonance imaging (MRI) methods of determining width and length of the lateral meniscus with actual dimensions after anatomic dissection. Study Design: Controlled laboratory study. Methods: Ten fresh-frozen human cadaveric knees without any evidence of meniscal or ligamentous injury were primarily imaged using radiography and MRI and subsequently underwent dissection to assess the anatomic size of each meniscus. Four methods were used to predict the size of the lateral menisci: anthropometric, radiographic (Pollard and Yoon), and MRI. Absolute differences in length and width between actual and predicted sizes were determined. Results: The anatomic lateral meniscal width and length were 33.01 ± 4.25 mm (mean ± SD; range, 24.84-40.18 mm) and 31.41 ± 5.06 mm (range, 25.2-40.05 mm), respectively. Regarding width, the anthropometric method demonstrated an absolute difference from anatomic measurement significantly greater when compared with the Pollard technique and MRI (P = .002). Regarding length, the Pollard method presented an absolute difference significantly greater than all other techniques (P = .003). In terms of the ability to measure width and length, MRI accurately predicted meniscal size within 10% of the anatomic size in 65% of measurements, the Yoon method in 54%, and the Pollard method in 20% (P = .01). Radiographs tended to overestimate the true size of the lateral meniscus, while the anthropometric technique overestimated width in all specimens. Conclusion: This study demonstrated that MRI and the Yoon radiographic method are comparable in terms of accuracy for graft sizing before lateral meniscal transplantation. While MRI is useful, a contralateral MRI is required, which makes the Yoon radiographic method recommended given the ease and cost advantage. The original Pollard technique and the anthropometric method are not recommended. Clinical Relevance: Over- and undersizing of meniscal transplants has been implicated in graft failure. Therefore, increasing the reliability of preoperative meniscal measurements is deemed important for the success of meniscal allograft transplantation.

Lateral meniscal allograft transplantation and stabilisation in a dog with stifle subluxation

This case describes the clinical features and the favourable clinical outcome after a lateral meniscal allograft transplant and stifle stabilisation in a dog that suffered a significant injury to its...

Lateral Meniscal Graft Transplantation: Effect of Fixation Method on Joint Contact Mechanics During Simulated Gait

Background: Controversy exists regarding the optimal bony fixation technique for lateral meniscal allografts. Purpose/Hypothesis: The objective was to quantify knee joint contact mechanics across the lateral plateau for keyhole and bone plug meniscal allograft transplant fixation techniques throughout simulated gait. It was hypothesized that both methods of fixation would improve contact mechanics relative to the meniscectomized condition, while keyhole fixation would restore the distribution of contact stress closer to that of the intact knee. Study Design: Controlled laboratory study. Methods: Six human cadaveric knees were mounted on a multidirectional dynamic simulator and subjected to the following conditions: (1) native intact meniscus, (2) keyhole fixation of the native meniscus, (3) bone plug fixation of the native meniscus, and (4) meniscectomy. Contact area, peak contact stress, and the distribution of stress across the tibial plateau were computed at 14% and 45% of the gait cycle, at which axial forces are at their highest. Translation of the weighted center of contact stress throughout simulated gait was computed. Results: Both bony fixation techniques improved contact mechanics relative to the meniscectomized condition. The keyhole technique was not significantly different from the intact condition for the following metrics: contact area, peak contact stress, distribution of force between the meniscal footprint and cartilage-to-cartilage contact, and the position of the weighted center of contact. In contrast, bone plug fixation resulted in a significant decrease of 21% to 28% in contact area at 14% and 45% of the simulated gait cycle, a significant increase in peak contact stresses of 34% at 45% of the gait cycle, and a shift in the weighted center of contact, which increased forces in the cartilage-to-cartilage contact area at 45% of the gait cycle. Conclusion: While both keyhole and bone plug fixation methods improved lateral compartment contact mechanics relative to the meniscectomized knee, keyhole fixation restored contact mechanics closer to that of the intact knee. Clinical Relevance: Method of meniscal fixation is under the direct control of the surgeon. From a biomechanics perspective, keyhole fixation is advocated for its ability to mimic intact knee joint contact mechanics.

Lateral Meniscus Allograft Transplantation: The Bone Plug Technique

Lateral meniscus tears are commonly encountered by orthopaedic surgeons. Despite efforts to repair and preserve the meniscus, meniscectomy is occasionally required to treat irreparable tears. The resulting lateral meniscus deficiency leads to increased tibiofemoral contact pressures and ultimately early osteoarthritic changes in the knee. Lateral meniscal allograft transplant (LMAT) has been proposed as a way to restore the lateral meniscus–deficient knee to its native form. Although several techniques for LMAT have been proposed, osseous fixation has demonstrated increased stability, improved outcomes, and improved long-term survival. This article presents a technique for LMAT using bone plugs and standard arthroscopic portals.

Lateral Meniscal Allograft Transplant via a Medial Approach Leads to Less Extrusion

Background: Accurate positioning of the bony bridge is crucial to prevent extrusion of meniscal allografts after transplant. However, oblique or lateralized placement of the bony bridge of the lateral meniscal allograft may occur due to technical error or a limited visual field. The patellar tendon may be an obstacle to approaching the anterior horn of the lateral meniscus, resulting in a laterally placed allograft. Therefore, lateral meniscal transplant through a medial arthrotomy would be an alternative approach. However, no report exists regarding allograft extrusion when comparing medial and lateral arthrotomy techniques in lateral meniscal transplants. Hypothesis: Extrusion of the midbody of the allograft is less severe and the rotation of the bony bridge is less oblique in lateral meniscal allograft transplants through the medial parapatellar approach than those through the lateral approach. Study Design: Cohort study; Level of evidence, 3. Methods: A bony bridge was used to perform 55 lateral meniscal transplants through either a medial or a lateral arthrotomy. Thirty-two allografts were transplanted through a medial arthrotomy and 23 were transplanted through a lateral arthrotomy, not randomly. Because correct positioning of the bony trough through the medial arthrotomy was easier than that through the lateral arthrotomy, the method of the arthrotomy was changed for the latter. The procedure for both groups was identical except for the arthrotomy technique, and rehabilitation was identical for both groups. Follow-up magnetic resonance imaging was conducted for all patients to measure the postoperative extrusion and obliquity of the bony bridge of the allograft. On the coronal view, extrusion was measured as the distance between the outer edge of the articular cartilage of the lateral tibial plateau and the outer edge of the meniscal allograft. On the axial view, a line (line B) was drawn along the longitudinal axis of the bony bridge. The posterior tibial condylar tangential line was drawn between the medial and lateral posterior tibial condylar cortices. A line (line T) was drawn perpendicular to the posterior tibial condylar tangential line. The angle (trough angle) between lines B and T was measured. Postoperative extrusion and the trough angle were compared between the medial and lateral arthrotomy groups. Results: The median extrusion of the midbody of the allograft was 2.2 mm (interquartile range [IQR], 2.4 mm; range, 0-4.6 mm) in the medial arthrotomy group and 3.1 mm (IQR, 1.5 mm; range, 0-5.3 mm) in the lateral arthrotomy group (P = .001). Seven (21.9%) patients demonstrated extrusion in the medial arthrotomy group, and 15 (65.2%) patients had extrusion in the lateral group (P = .002). The median trough angle was 0.9° (IQR, 9.3°; range, -8.8-15.8°) in the medial arthrotomy group and 11.6° (IQR, 2.8°; range, 3-19.8°) in the lateral arthrotomy group (P < .001). Conclusion: Based on this experience, lateral meniscal allograft transplant through a medial arthrotomy is preferred to decrease postoperative extrusion of the allograft.

Midterm and Long-term Results of Medial Versus Lateral Meniscal Allograft Transplantation: A Meta-analysis

Background: It is unclear whether lateral meniscal allograft transplantation (MAT) procedures lead to better clinical outcomes than medial MAT. Hypothesis: The survival rates are similar between medial and lateral MAT, but the clinical outcomes of lateral MAT are better than those of medial MAT at final follow-up. Study Design: Meta-analysis. Methods: In this meta-analysis, we reviewed studies that assessed survival rates in patients who underwent medial or lateral MAT with more than 5 years of follow-up and that used assessments such as pain and Lysholm scores to compare postoperative scores on knee outcome scales. The survival time was considered as the time to conversion to knee arthroplasty and/or subtotal resection of the allograft. Results: A total of 9 studies (including 287 knees undergoing surgery using medial MAT and 407 with lateral MAT) met the inclusion criteria and were analyzed in detail. The proportion of knees in which midterm (5-10 years) survival rates (medial, 97/113; lateral, 108/121; odds ratio [OR] 0.71; 95% CI, 0.31-1.64; P = .42) and long-term (>10 years) survival rates (medial, 303/576; lateral, 456/805; OR 0.78; 95% CI, 0.52-1.17; P = .22) were evaluated did not differ significantly between medial and lateral MAT. In addition, both groups had substantial proportions of knees exhibiting midterm survivorship (85.8% for medial MAT and 89.2% for lateral MAT) but much lower proportions of knees exhibiting long-term survivorship (52.6% for medial MAT and 56.6% for lateral MAT). In contrast, overall pain score (medial, 65.6 points; lateral, 71.3 points; 95% CI, −3.95 to −0.87; P = .002) and Lysholm score (medial, 67.5 points; lateral, 72.0 points; 95% CI, −10.17 to −3.94; P < .00001) were significantly higher for lateral MAT compared with medial MAT. Conclusion: Meta-analysis indicated that 85.8% of medial and 89.2% of lateral meniscal allograft transplants survive at midterm (5-10 years) while 52.6% of medial and 56.6% of lateral meniscal allograft transplants survive long term (>10 years). Patients undergoing lateral meniscal allograft transplantation demonstrated greater pain relief and functional improvement than patients undergoing medial meniscal allograft transplantations.

Meniscal Extrusion Does Not Progress During the Midterm Follow-up Period After Lateral Meniscal Transplantation

Background: Meniscal extrusion is related to degeneration of the native knee joint. However, the clinical effect of the phenomenon after meniscal allograft transplantation (MAT) has not been clearly identified. Purpose/Hypothesis: The purpose of this study was to evaluate the change in meniscal extrusion in both the coronal and sagittal planes after lateral MAT through the midterm follow-up period. We hypothesized that meniscal extrusion does not progress during the midterm follow-up period. Study Design: Case series; Level of evidence, 4. Methods: A total of 46 patients with a mean follow-up of 51.1 ± 7.1 months were included in the study. The patients underwent lateral MAT using the keyhole technique. Postoperative magnetic resonance imaging (MRI) was performed at 6-week, 1-year, and midterm (3- to 5-year) follow-up. In the coronal plane, the absolute value of meniscal subluxation and the relative percentage of extrusion (RPE) were measured. In the sagittal plane, meniscal subluxation was measured as the absolute and relative anterior cartilage meniscal distance (ACMD) and posterior cartilage meniscal distance (PCMD). The joint-space width (JSW) on weightbearing radiographs with 2 different knee positions was measured preoperatively and at 1-year and midterm follow-up. The Lysholm score was assessed at the same time points. Results: In the coronal plane, the mean absolute meniscal extrusion at 6-week, 1-year, and final follow-up was 2.90 ± 0.94, 2.85 ± 0.97, and 2.83 ± 0.89 mm, respectively, and the mean RPE was 27.0% ± 9.4%, 27.1% ± 10.1%, and 27.8% ± 9.7%, respectively. There were no statistically significant differences in absolute and relative coronal extrusion among the 3 time periods (P > .05). The percentage of patients with meniscal extrusion (≥3 mm) was 37.0% at 6-week follow-up and 34.8% at 1-year and final follow-up. In the sagittal plane, the mean absolute ACMD was 2.59 ± 1.75, 2.58 ± 1.85, and 2.37 ± 1.60 mm, respectively, and the mean relative ACMD was 20.7% ± 13.1%, 20.6% ± 13.8%, and 19.0% ± 12.2%, respectively, at the 3 follow-up time points. The mean absolute PCMD was −1.23 ± 3.34, −1.28 ± 3.08, and −1.42 ± 2.77 mm, respectively, and the mean relative PCMD was −10.3% ± 25.9%, −11.0% ± 24.6%, and −12.2% ± 23.2%, respectively, at the same time points. Sagittal extrusion was not significantly different between the time points (P > .05). The mean JSW at 2 days preoperatively, 1 year postoperatively, and midterm follow-up was 5.40 ± 1.07, 5.44 ± 1.04, and 5.43 ± 0.98 mm, respectively, on anterior-posterior radiographs with full extension, and it was 4.90 ± 0.94, 4.94 ± 0.98, and 4.89 ± 0.96 mm, respectively, on posterior-anterior radiographs with 45° of flexion. The mean JSW values were not significantly different between the 3 different time points (P > .05). The mean preoperative Lysholm score was 58. 9 ± 8.3; the score increased to 90.4 ± 9.7 at 1 year postoperatively and 90.5 ± 10.1 at final follow-up, which is a significant improvement compared with the preoperative status (P < .05). There was no statistically significant difference between the scores at the 2 postoperative time points (P > .05). Conclusion: This study demonstrated that extrusion of the meniscal allograft did not significantly progress either in the coronal or sagittal plane after lateral MAT during the midterm follow-up period.

Prospective Clinical and Radiographic Outcomes After Concomitant Anterior Cruciate Ligament Reconstruction and Meniscal Allograft Transplantation at a Mean 5-Year Follow-up

Background: Concomitant anterior cruciate ligament reconstruction and meniscal allograft transplantation (ACLR/MAT) has demonstrated short-term success in small, retrospective cohort studies. Patient- and disease-specific predictors of success after ACLR/MAT are largely unknown. Purpose: To (1) prospectively evaluate the subjective and objective clinical and radiographic outcomes after ACLR/MAT and (2) conduct a subgroup analysis to identify patient- or disease-related factors that correlate with failure. Study Design: Case series; Level of evidence, 4. Methods: Patient-reported outcomes (PROs) were prospectively collected on 40 patients undergoing concomitant ACLR/MAT. Nineteen athletes responded to return-to-sport data. Clinical data (physical examination including Lachman and pivot-shift testing and KT-1000 arthrometer testing) were obtained on 28 patients who returned for an evaluation, while 24 of those patients additionally had radiographic data (progression of Kellgren-Lawrence [KL] grade and joint-space narrowing) evaluated. Reoperations and failures were documented for all patients at their final follow-up. Results: The overall cohort of 40 patients had a mean age of 30.3 ± 9.6 years (range, 16.0-54.0 years) and a mean body mass index of 27.7 ± 4.2 kg/m2. The mean follow-up time was 5.7 ± 3.2 years (range, 1.7-16.5 years). There were 33 (83%) medial meniscal transplants performed compared with 7 (17%) lateral meniscal transplants. Patients underwent a mean of 2.9 ± 1.9 prior surgical procedures. Nineteen patients underwent concomitant procedures, including, most commonly, 9 hardware removals and 9 osteochondral allografts. There were significant improvements in 11 of 14 PRO measures as well as a 50% return-to-sport rate. Knee stability significantly improved in 28 patients who returned for a physical examination, and KT-1000 arthrometer testing indicated no differences between the affected and unaffected sides at final follow-up (mean, 0.9 ± 1.5 mm [range, –2 to 4 mm] in comparison to contralateral knee at 30 lb of testing; mean, 0.9 ± 1.9 mm [range, –4 to 4 mm] in comparison to contralateral knee at maximum manual strength). Significant improvements were seen in patients with Lachman grade ≥2A at final follow-up (18% vs 97%, respectively; P < .01) and with pivot shift ≥1+ at final follow-up (36% vs 94%, respectively; P < .01) compared with preoperatively. For the 24 patients with radiographic data, no significant joint-space decrease was recorded in the medial compartment for medial MAT–treated patients or the lateral compartment for lateral MAT–treated patients. The mean KL grade increased from 0.7 ± 0.8 to 1.6 ± 0.9 at final follow-up (P < .01). There were no major (0%) and 2 minor (5%) complications, which constituted early postoperative drainage treated successfully with oral antibiotics. While 35% of patients underwent reoperations, the majority of these were simple arthroscopic debridements and occurred after nearly 4 years from the index surgery. The overall survival rate at final follow-up was 80%. Failures occurred at a mean of 7.3 years, and those who converted to arthroplasty did so at a mean of 8.3 years from the time of index ACLR/MAT. Patients with failed grafts were more frequently associated with workers’ compensation claims (38% vs 13%, respectively) and less frequently self-identified as athletes (13% vs 56%, respectively) compared with patients with intact grafts. Conclusion: Concomitant ACLR/MAT can provide significant improvements in clinical outcomes and enhancement in objective knee stability and was associated with an insignificant degree of radiographic joint-space narrowing changes with a 5-year survivorship of more than 80% for those with data available. Athlete status may be a preoperative predictor of midterm survival.

Osteochondral Proximal Tibial and Lateral Meniscal Allograft Transplant

Knee pain in young, active patients with meniscus-deficient knees and articular cartilage damage can present a challenge to treatment. Meniscal allograft transplantation (MAT) has shown good clinical results as treatment for meniscus deficiency; however, worse outcomes have been observed in patients with significant chondral damage. The development of chondral restorative techniques such as osteochondral allograft transplantation (OCA) has expanded the population of patients who may benefit from MAT. We present a case of proximal tibial osteochondral and lateral meniscal allograft transplant. This review includes a sample of patient examinations and imaging, followed by a detailed technical description of the case. The technique article concludes with a discussion on the niche combined MAT-OCA procedures occupy in the patient treatment realm.

The management of the popliteus hiatus during lateral meniscal transplantation

Popliteofascicular injury had been proposed as a possible cause of unstable lateral meniscus. Meniscal repair at popliteal hiatus area during lateral meniscal allograft transplantion (MAT) had not been described in literature previously. In this report, a case of unstable lateral meniscus after MAT has been described. Arthroscopic repair for the unstable meniscus at popliteal hiatus resolved the mechanical symptom.

Corrigenda/Errata

Koh Y-G, Moon H-K, Kim Y-C, Park Y-S, Jo S-B, Kwon S-K. Comparison of medial and lateral meniscal transplantation with regard to extrusion of the allograft, and its correlation with clinical outcome.

Comparison of medial and lateral meniscal transplantation with regard to extrusion of the allograft, and its correlation with clinical outcome

We compared extrusion of the allograft after medial and lateral meniscal allograft transplantation and examined the correlation between the extent of extrusion and the clinical outcome. A total of 73 lateral and 26 medial meniscus allografts were evaluated by MRI at a mean of 32 months (24 to 59) in 99 patients (67 men, 32 women) with a mean age of 35 years (21 to 52). The absolute values and the proportional widths of extruded menisci as a percentage were measured in coronal images that showed maximum extrusion. Functional assessments were performed using Lysholm scores. The mean extrusion was 4.7mm (1.8 to 7.7) for lateral menisci and 2.9 mm (1.2 to 6.5) for medial menisci (p < 0.001), and the mean percentage extrusions were 52.0% (23.8% to 81.8%) and 31.2% (11.6% to 63.4%), respectively (p < 0.001). Mean Lysholm scores increased significantly from 49.0 (10to 83) pre-operatively to 86.6 (33 to 99) at final follow-up for lateral menisci (p = 0.001) and from 50.9 (15 to 88) to 88.3 (32 to 100) for medial menisci (p < 0.001). The final mean Lysholm scores were similar in the two groups (p = 0.312). Furthermore, Lysholm scores were not found to be correlated with degree of extrusion (p = 0.242). Thus, transplanted lateral menisci extrude more significantly than transplanted medial menisci. However, the clinical outcome after meniscal transplantation was not found to be adversely affected by extrusion of the allograft.

Width is a more important predictor in graft extrusion than length using plain radiographic sizing in lateral meniscal transplantation

Plain radiographs are frequently used to select appropriately sized meniscal allografts, of which the width and length cannot be always perfectly matched. The objective of this study was to decide which of these dimensions should be matched with a more priority considering proper position of the lateral meniscal transplants. The positions of 34 lateral, fresh-frozen meniscal allografts, transplanted using the central bone bridge method, were evaluated by magnetic resonance imaging (MRI) 2days after surgery. A size mismatch was defined as a difference between preoperative radiographic size and a real dimension of the transplants. The lateral subluxation of the mid-body on the coronal plane and the anterior and posterior horn positions on the sagittal plane were estimated on the MRIs. It was evaluated whether size mismatches were associated with the meniscal subluxation beyond articular cartilage margin on each plane. The mean lateral subluxation of the mid-body on the center of coronal sections was 1.7±1.8mm. The anterior and posterior horns were located 2.0±2.1mm and -3.8±2.7mm from the articular edge, respectively, in the center of sagittal images. Lateral subluxation was significantly associated with width mismatch (r=0.415-0.486, P<0.05), but length mismatch was not significantly correlated with the anterior or posterior horn position on sagittal images (n.s.). The results of this study suggest that width matching using plain radiographs would be more reliable than length matching when it is sought to assure adequate positioning of meniscal transplants, if both dimensions cannot be simultaneously matched. II.

Both the medial and lateral meniscal allograft transplantation following the anterior cruciate ligament reconstruction by arthroscopic surgical technique

To discuss the minimal invasive arthroscopic surgery technique and clinical results of both the medial and lateral meniscal transplantation following the anterior cruciate ligament reconstruction with double bundles and bone tunnels. In August 2008 a minimal invasive surgery of both the medial and lateral meniscal allograft transplantation following anterior cruciate ligament reconstruction was preformed for 1 case with both the medial and lateral meniscectomy by arthroscopic surgery. The method of two bone plugs attached on tibial plateau was employed for medial meniscal allograft transplantation and the technique the bridge in slot for lateral meniscal allograft transplantation. The VAS, Lysholm score and IKDC rating were recorded before and after operation. The stability of knee was assessed by Lachman test, drawer sign and pivot shift test. The patient was followed up 26 month after the operations. The degrees of knee flexion, extension and function of walk were normal. The Lachman test, drawer sign and pivot shift test were nearly normal. The VAS after operation was 2 points lower than that before operation. The Lysholm score post-operation was 20 points higher than pre-operation. The IKDC became B degree in late following-up from C degree before the operation. MRI revealed anterior cruciate ligament graft was continuous and the meniscal allograft was normal shape on year 1 after the operation. The posterior horn of medial meniscal allograft and anterior corner of lateral meniscal allograft showed slightly shrunk. The second-look arthroscopy showed that the healing occurring between meniscal allograft and the capsule and meniscal allograft was normal shape on month 18 after the operation. The anterior horn of medial and lateral meniscus was slightly worn. Both the medial and lateral meniscal transplantation following the anterior cruciate ligament reconstruction in appropriately selected patients with the medial and lateral meniscus-deficient knee may recover the knee mechanic balance and stability, which is a option of treatment for that young and activity patients. It is proposed that the medial and lateral meniscal grafts harvested from a single donator. Attention should be paid to the direction of the bone tunnels fixing the horns of the meniscus in order to avoid communication with the tunnels of anterior cruciate ligament reconstruction.

Meniscal Allograft Transplantation

Meniscal allograft transplantation (MAT) has become an accepted treatment option for patients undergoing meniscectomy with recalcitrant pain in the corresponding compartment. Whether MAT can oppose cartilage degeneration is unclear. Our purpose was to perform a systematic review of available literature to answer the following: (1) Does MAT prevent advancing chondrosis? (2) Who is the ideal candidate for MAT? (3) What is the survival time for allograft in a stable knee? (4) Can MAT be successful when performed with concomitant procedures? (5) Is there an outcome difference between medial and lateral meniscal allograft transplants? (6) What is the expected function of a knee that has undergone MAT? Two authors performed a systematic review of the literature pertaining to MAT. Included in the review are studies with at least 2 years' follow-up, studies with validated outcome measures, and studies in which the allograft meniscal horns were secured with bony fixation. We identified 14 clinical articles that satisfied our inclusion and exclusion criteria. Thirteen of the articles provided Level IV evidence, and one article provided Level III evidence. MAT can result in alleviation of knee pain, improvement in knee function, and good patient satisfaction if performed in the optimal candidate. Improvements in both objective and subjective outcome measures were shown in relatively young patients without significant chondromalacia who underwent concomitant procedures for cartilage defects, limb malalignment, and/or knee instability. We detected no significant difference in outcomes when comparing medial and lateral meniscal allograft transplants. We detected no significant difference when comparing isolated MAT with MAT performed with concomitant procedures. Level IV, systematic review of Level III and IV studies.

A Modified Keyhole Technique for Minimizing Size Mismatches During a Smaller than Optimal Lateral Meniscal Allograft Transplantation

Despite careful preoperative and intraoperative sizing of lateral menisci in recipient knees, size mismatches between allografts and recipient menisci are often encountered. To minimize size mismatches during the transplantation of smaller than expected lateral meniscal allografts, we devised a modified keyhole technique by dividing the central bone bridge into 2 bony fragments. The fragments are attached to the anterior and posterior horns. In the event of mismatch, the anterior bony fragment is moved anteriorly in the keyhole tunnel. Although the technique of meniscal transplantation is technically demanding, the central bone bridge can be divided without difficulty. The described technique is considered a useful alternative method during lateral meniscal transplantation.

Time dependent properties of bovine meniscal attachments: Stress relaxation and creep

It has been suggested that the success of a meniscal replacement is dependent on several factors, one of which is the secure fixation and firm attachment of the replacement to the tibial plateau [Chen, M.I., Branch, T.P., et al., 1996. Is it important to secure the horns during lateral meniscal transplantation? A cadaveric study. Arthroscopy 12(2), 174–181; Alhalki, M.M., et al., 1999. How three methods for fixing a medial meniscal autograft affect tibial contact mechanics. American Journal of Sports Medicine 27(3), 320–328; Haut Donahue, T.L., et al., 2003. How the stiffness of meniscal attachments and meniscal material properties affect tibio-femoral contact pressure computed using a validated finite element model of the human knee joint. Journal of Biomechanics 36(1), 19–34]. The complex loading environment in the knee lends itself to different loading environments for each meniscal attachment. We hypothesize that the creep and stress relaxation characteristics of the horn attachments will be different for the anterior versus posterior, and medial versus lateral attachments. To test this hypothesis, the stress relaxation and creep characteristics of the meniscal horn attachments were determined. The stress relaxation properties of load/stress at the end of the test, and the load/stress relaxation rate demonstrated no significant statistical differences between the attachments. Unlike the stress relaxation properties, the creep properties demonstrated some significant differences amongst the attachments. The normalized displacement at the end of the test, normalized creep rate and strain creep rate for the lateral anterior attachment were significantly different than those of the medial posterior attachment ( p < 0.0 5 ). The two anterior attachments had significantly different strains at the end of the test, as well as significantly different creep strain rates ( p < 0.0 5 ). The two attachments of the medial meniscus revealed no significant differences between any of the creep properties measured ( p > 0.0 5 ). The time dependent properties obtained in this experiment provide insight into the behavior of meniscal horn attachments under various loading situations. The results indicate that a suitable meniscal replacement may require different properties for the lateral and medial horns.