Cryopreservation does not alter the ultrastructure of the meniscus

Fresh frozen menisci have recently been shown to have an altered meniscal ultrastructure. The cause might be a deterioration of its permeability due to collagen net disarray. The purpose of this study was to evaluate the cryopreserved meniscus in terms of ultrastructure and cellularity. Ten fresh human lateral menisci were harvested. Collagen architecture was evaluated with transmission electron microscopy. The Collagen Meniscal Architecture scoring system was used to assess the degree of meniscal disarray. Cell population, was also evaluated. The fibril collagen diameters of those menisci which had been previously cryopreserved showed an average size in the longitudinal section of 12.6 ± 1.3 nm, whereas it was 13.4 ± 2.2 nm in the menisci used as controls (n.s.). In the transverse section, the cryopreserved menisci averaged 15.5 ± 2.4 and 16.7 ± 3.5 nm in the controls (n.s.). The study group scored 4.8 points ± 1.7, whereas the control group did so at 4.1 ± 1.3 (n.s.). The percentage of cell survival after the cryopreservation ranged from 4 to 54. The fibril diameters and degree of disarray showed a similar distribution in both groups. The results suggest that meniscal cryopreservation does not alter the meniscal ultrastructure. Therefore, an allograft stored in that way would not alter its biomechanical properties, although its cellular viability is highly unpredictable.     

Presumptive subarticular stress reactions of the knee: MRI detection and association with meniscal tear patterns

Objective MRI detects subchondral marrow findings in painful knees which bear resemblance to spontaneous osteonecrosis of the knee (SONK). Gathering evidence suggests that the primary or predominant pathogenesis of these lesions is physical stress. This study analyzes the patient characteristics and meniscal pathology associated with these lesions—herein referred to as presumptive subarticular stress related (PSSR) lesions.Design and patients All patients were scanned using a standardized imaging protocol. The criterion for a PSSR lesion was a subchondral marrow edema pattern encompassing a more focal, low-signal zone adjacent to or contiguous with the subchondral cortex. Patients were identified using an electronic database search of cases reported by one experienced musculoskeletal radiologist.Results Twenty-five PSSR lesions were identified among 1,948 MRI evaluations of the knee. Twenty-one PSSR lesions occurred in the medial compartment, and four occurred in the lateral compartment. There was no sex predilection. Patients with PSSR lesions were older than other patients undergoing MRI evaluation (mean 66 years versus 52 years, P<0.001). Meniscal tears occurred more commonly in cases with PSSR lesions than in the group as a whole (76% versus 45%, P<0.001). Radial and posterior root tears were more common in knees with PSSR lesions than in other knees with meniscal tears (53% versus 26%, P<0.01).Conclusions PSSR lesions are associated with meniscal tears and, more specifically, with meniscal tear patterns that dramatically increase contact forces across the knee joint. This observation supports the hypothesis that mechanical stress is important in the pathogenesis of these subarticular lesions that are detected by MRI.     

半月板缝合术后应用七叶皂苷钠治疗腿肿与关节腔积液

目的:七叶皂苷钠预防、治疗关节镜下半月板缝合术后肢体肿胀及关节腔积液.方法:术后采用随机分组,将关节镜下半月板缝合术后病人分为A、B两组,每组30例;A组为七叶皂苷钠治疗,B组为对照组(不用药组).观察肢体肿胀及关节腔积液情况.结果:用药组与对照组相比小腿肿胀、关节积液发生率比较(P＜0.01)有统计学差异.结论:七叶皂苷钠是目前较理想的经济、安全、有效的关节微创术后治疗用药之一,值得临床推广使用.     

The influence of meniscal lesions on reflex activity in the hamstring muscles

Meniscal lesions are among the most common knee injuries and substantially affect the mechanical function of the knee joint. In addition, the presence of mechanoreceptors in the meniscus suggests that the menisci are also involved in the sensorimotor control of the knee. The objective of this study was to investigate the influence of an isolated meniscal lesion on the reflex behaviour of the hamstring muscles, which are involved in the sensorimotor control of the knee joint. For this purpose, we mechanically induced tibial translation in 19 patients in a standing position and analysed the biphasic response of the hamstrings consisting of a short-latency response (SLR) and a medium-latency response (MLR). Moreover, we determined anterior tibial translation. A comparison of electromyographic data for the healthy legs versus the injured legs showed no significant differences in either SLRs or MLRs. Although there was a tendency to an increase in tibial translation, no significant difference between the legs in anterior tibial translation was found. In conclusion, our experimental work did not reveal any substantial effects of a meniscal lesion on the reflex behaviour of the hamstrings. Our data suggest that the menisci appear to play only a minor role for the sensorimotor induced anterior posterior knee stability.     

Kinematic I and Oxford knee arthroplasty: A 5–8-year follow-up study

Sixty-seven consecutive Oxford Meniscal total knee arthroplasties (TKAs) were compared prospectively with 66 Kinematic I TKAs. At follow-up examination an average of 5.5 (range, 5-8) years later, 20 (30%) of the Oxford Meniscal TKAs had been revised (nine due to aseptic loosenings, seven to aseptic loosening and patellofemoral syndrome, two to patellofemoral syndrome, one to meniscal bearing dislocation, and one to sepsis) and in 16% one or more of the remaining tibial components was radiographically at risk. Three (5%) Kinematic I TKAs had been reoperated upon (one for anterior dislocation, one for a loose patellar component, and one for sepsis) and no component was considered radiographically at risk. The remaining cases demonstrated good and excellent knee ratings (Oxford, 82 +/- 11; Kinematic I, 88 +/- 6; P less than .01; Hospital for Special Surgery). This study suggests that the results of Kinematic I TKA are superior to those of Oxford Meniscal TKA; that patellofemoral resurfacing is advisable; and that Kinematic I TKA yields 5-year data comparable to those of total hip arthroplasty.     

提高上浆效果的探讨

研究了浸浆机理，并作了４个方案的试验。浸浆时加上一些机械作用，以加快润湿和吸附，显著提高了上浆效果。     

Displacement of the medial meniscus within the passive motion characteristics of the human knee joint: an RSA study in human cadaver knees

The objective of this study was to validate an in vitro human cadaver knee-joint model for the evaluation of the meniscal movement during knee-joint flexion. The question was whether our model showed comparable meniscal displacements to those found in earlier meniscal movement studies in vivo. Furthermore, we determined the influence of tibial torque on the meniscal displacement during knee-joint flexion. Three tantalum beads were inserted in the medial meniscus of six human-cadaver joints. The knee joints were placed and loaded in a loading apparatus, and the movements of the beads were determined by means of RSA during knee-joint flexion and extension with and without internal tibial (IT) and external tibial (ET) torque. During flexion without tibial torque, all menisci moved in posterior and lateral direction. The anterior horn showed significantly greater excursions than the posterior horn in both posterior and lateral direction. Internal tibial torque caused an anterior displacement of the pathway on the tibial plateau. External tibial torque caused a posterior displacement of the pathway. External tibial torque restricted the meniscal displacement during the first 30° of knee-joint flexion. The displacements of the meniscus in this experiment were similar to the displacements described in the in vivo MRI studies. Furthermore, the application of tibial torque confirmed the relative immobility of the posterior horn of the meniscus. During external tibial torque, the posterior displacement of the pathway on the tibial plateau during the first 30° of flexion might be restricted by the attached knee-joint capsule or the femoral condyle. This model revealed representative meniscal displacements during simple knee-joint flexion and also during the outer limits of passive knee-joint motion.     

Repair of meniscal tears with the absorbable Clearfix screw: results after 1–3 years

Introduction Total meniscus resection usually leads to osteoarthritis of the knee joint. Preservation and refixation of the injured menisci are therefore of great clinical importance.Materials and methods The present study examines 40 meniscal injuries in 37 patients that were arthroscopically treated with Clearfix meniscal screws (Mitek, Norderstedt, Germany) in the period from August 1999 to December 2002. The mean patient age was 27.7 (range 16–62) years. Nine patients were female. A total of 24 patients (27 meniscal tears) also had an anterior cruciate ligament (ACL) lesion, and 5 patients had cartilage injuries. Twenty-two patients were treated within the first 2 weeks following the trauma, 10 patients within 8 weeks, and 5 patients after 8 weeks. The lesions were a bucket-handle tear of the medial meniscus in 11 cases and a bucket-handle tear of the lateral meniscus in 2 cases. The posterior horn of the medial meniscus was torn in 13 cases, and the pars intermedia in 3 cases. The posterior horn of the lateral meniscus was torn in 8 cases, and the pars intermedia in 3 cases. The mean tear length was 2.9 (±1.5) cm and was fixed with an average of 1.8 (±0.7) screws. In 7 cases, the anterior horn was treated with an additional meniscal suture. A total of 35 patients were examined after an average of 18 (range 7–45) months.Results In the event of a moderate outcome, MRI was performed as part of the follow-up investigation. The average Lysholm score was 93 (±7.4), the Tegner activity index was 6.3 (±2.0) before the accident and 5.8 (±2.0) at the follow-up, the Marshall knee score was 47 (±3.8). The VAS pain assessment was 1.6 (±1.3) and the VAS function assessment was 7.9 (±1.6). Of the 7 patients with a moderate result, 2 patients without additional ligament lesions suffered re-ruptures after 6 and 13 months, respectively. The other 5 patients with a moderate result each had multiple accompanying injuries or pre-existing damage to the affected knee joint.Conclusion The Clearfix screws achieved a clinical success rate of 82% in isolated meniscal tears in stable knee joints and a clinical success rate of 100% with additional ACL reconstruction. In view of the good clinical results and the simple procedure for use, the implant should be recommended for meniscal refixation.