膝关节镜下自体髌韧带重建前交叉韧带手术探讨

目的报告关节镜下采用中1/3骨-髌韧带-骨(BPTB)等长重建前交叉韧带手术10例,并对临床疗效进行分析讨论.方法经临床及关节镜检查确诊的前交叉韧带(ACL)损伤患者10例,平均年龄22.3岁(17～26岁),取自体BPTB中1/3,关节镜下重建其ACL.术后随访时间16个月(12～20个月),参照敖英芳临床判断标准及lysholm评分评价疗效.结果临床效果优者3例,良5例,中1例,差1例.Lysholm评分术前(23.8±8.53)分,术后(88±7.48)分(P＜0.01).术后3例合并膝前疼痛,其中2例接受再次关节镜手术,再次镜检证实为脂肪垫挤压综合征,均于手术后恢复.结论膝关节镜下自体髌韧带重建前交叉韧带,近期疗效肯定,术后恢复快,但膝前疼痛并发症的防治值得探讨.     

Primary stability of bone-patellar tendon-bone graft fixation with biodegradable pins

Purpose: We evaluated the initial bone-patellar tendon-bone (BPTB) graft fixation strength of biodegradable pins compared with interference screws in anterior cruciate ligament reconstruction using bovine knees. Type of Study: Biomechanical in vitro study. Methods: Ten BPTB grafts from human donors fixed with 2 biodegradable 2.7-mm pins (Rigid Fix; Ethicon, Mitek Division, Norderstedt, Germany) crossing the bone block perpendicular and 10 BPTB grafts fixed with conventional biodegradable interference screws (Absolute Absorbable Interference Screw; Innovasive Devices, Marlborough, MA) underwent ultimate single-cycle failure loading at a rate of 200 mm/min. The grafts were fixed to bovine tibia to simulate young human femoral bone density. Failure mode, displacement before failure, and ultimate failure load were tested with a testing machine. The pullout force was in line with the bone tunnel to simulate a worst case scenario. Results: The failure mode for cross pins was either fracture of the bone block (5 specimens) or fracture of the articular pin (5 specimens). The failure mode for interference screws was slippage past the screw in all specimens. In the single cycle loading test, the mean yield load for the biodegradable pins was 400.2 (± 122.4) N, maximum load, 524.6 (± 136.6) N, with a mean stiffness of 155.2 (± 32.4) N/mm. The yield load at failure for the interference screw was 402.7 (± 143.9) N, maximum load 515.7 (± 168.5) N with a mean stiffness of 168 (± 42) N/mm. Conclusions: Fixation of a BPTB graft with 2 biodegradable 2.7-mm pins (Rigid Fix) leads to primary stability that is comparable to fixation with biodegradable interference screws.     

Effects of patellar position and defect healing on in vitro stifle joint kinematics following removal of the central one‐third of the patellar tendon in an ovine model

Harvest of the central one‐third of the patella tendon (PT) is routinely performed for anterior cruciate ligament reconstruction (ACLR). Patella infera may ensue. In this study we unilaterally resected the central one‐third of the PT in 20 sheep, without reconstructing or defunctionalizing the native ACL, and examined the effects at 3, 6, 12, and 24 weeks postoperatively on PT length, histological appearance of the donor defect and in vitro stifle joint kinematics. Mean length increases (p > 0.263) in the operated tendons of 0.3%, 2.8%, 0.5%, and 2.4% were observed at 3, 6, 12, and 24 weeks. A significant proximal shift of the patella correlated well with a mean 2.35° retardation of patellar flexion (r = 0.440, p = 0.001). A mean net 4.9° decrease in medial patellar tilt was also observed (p < 0.001), but was not coupled with changes in tibial rotation. Donor defect tissue showed a distinct progression of healing with time, remodeling from dense scar tissue at 3 weeks to bundles of well‐organized collagen enveloped by vascularized loose connective tissue at 24 weeks but was not associated with the restoration of kinematics. These results suggest that resection of the central one‐third of the PT and leaving the defect open in the ovine stifle joint may be associated with increased PT length and changes in patellar kinematics which do not recover 6 months postoperatively. The lack of patella infera may render this animal model unsuitable for the interpretation of joint kinematics following PT resection for human ACLR. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:572–581, 2011     

Biomechanical evaluation of a new cross-pin technique for the fixation of different sized bone–patellar tendon–bone grafts

To overcome the disadvantages of interference-screw fixation of bone–patellar tendon–bone (BPTB) grafts, new fixation techniques for anterior cruciate ligament (ACL) grafts using biodegradable pins have been developed. The hypothesis of the present study was that cross-pin fixation techniques provide a primary stability that is comparable to that of interference screws. A biomechanical in vitro study was discussed. Human BPTB grafts of 8, 9 and 10 mm diameter were fixed in bovine knees with biodegradable cross pins (diameter: 2.0, 2.7 or 3.2 mm) or biodegradable interference screws. Stiffness and ultimate load were evaluated. For 9 and 10 mm BPTB grafts, no statistically significant difference in maximum load and stiffness was found between the four fixation techniques tested. For 8 mm bone blocks the maximum load of the 3.2 mm pins (274.2 N) was significantly lower than for the 2.0 mm pins (479.8 N) and the interference screws (504.0 N). Predominant failure mode in this group was bone-block fracture. Thicker grafts (9 and 10 mm) fixed with the 2.0 mm pins predominantly failed by implant fracture. Femoral fixation of 8, 9 and 10 mm BPTB grafts using cross pins leads to biomechanical properties that are comparable to biodegradable interference screws when tested by a single-cycle load to failure. Cross pins provide a rigid fixation for 9 and 10 mm BPTB grafts.     

Alterations of the extensor apparatus after anterior cruciate ligament reconstruction using the medial third of the patellar tendon

Purpose: The objective of this study was the ultrasound evaluation of the donor defect of the patellar tendon (PT) and the radiologic evaluation of the patella after harvesting of the medial third as a bone–patella tendon–bone (BPTB) graft for anterior cruciate ligament (ACL) reconstruction. Type of Study: This was a cohort study. Methods: In 45 patients who had ACL reconstruction, the extensor apparatus of the donor side was studied using ultrasound cross-sections and radiographs (anteroposterior, lateral, and a tangential view of the patella) 3 to 70 months postoperatively. Patients were divided into two groups. The early postoperative group (3 to 30 months postoperative) consisted of 27 patients (group A) and the late postoperative group (31 to 70 months postoperative) consisted of 18 patients (group B). The healthy contralateral extensor apparatus was used as control. Results: In group A, the standard ultrasound cross-section area of the PT increased by 20.48%, whereas in group B, it decreased by 4.88%. In group A, the patellar height was decreased by 9.21% in the donor side compared with the control. In group B, the patellar height was decreased by 7.02%. In group A, the Merchant’s congruence angle increased by 11.59°, and for group B, this angle increased by 3.82°. This finding indicated that, after the 30th postoperative month, lateral displacement of the patella was not statistically significant (P = .38). In addition, no significant differences were found in the lateral patellofemoral angle in either group. Conclusions: Our study indicates that the tendon defect is always healed and the final tendon cross-section area is 95% of the contralateral after the 30th postoperative month. In addition, there was a nonsignificant slight lateral displacement of the patella. In contrast, other studies found shown that there is a slight medial displacement of the PT after using the central third as a BPTB graft.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 17, No 9 (November-December), 2001: pp 953–959