Anteromedial meniscofemoral ligament

We have experienced 3 cases of comparatively rare anteromedial meniscofemoral ligament in which the anterior horn of the medial meniscus was attached to the posterolateral wall of the femoral intercondylar fossa. In 2 of these cases, there was no attachment to the tibia, whereas in the other, it was connected to the lateral meniscus and also firmly to the tibia. In the 2 with no attachment to the tibia, abnormal mobility in the medial meniscus accompanied by flexion and extension of the knee was observed. Degeneration of the intermediate posterior segment and injury of the anterior horn were also observed. This anomaly induces a future meniscus injury, depending on the attachment state to the tibia.     

Dislocating anterior horn of the medial meniscus

Dislocating anterior horn of the medial meniscus was found in 15 knees of 13 patients during arthroscopic examinations done between 1992 and 1995. All of them were available for follow-up evaluation (4 by telephone). There were 11 men and 2 women (average age, 28 years; range, 17 to 49 years). Nine knees had a history of trauma. Only 1 knee had had trauma in two bilateral cases. Duration of symptoms was an average of 3.3 years (range, 3 months to 10 years). The knees were stable clinically. Arthroscopy revealed associated lesions in 13 knees; hypertrophic medial plicae, meniscal, chondral and anterior cruciate ligament (ACL) lesions predominated. Three knees had unusually hypertrophic ligamentum mucosum. Eleven of 13 knees had more than one associated lesions. Only 2 knees (2 patients) had isolated dislocating anterior horn of the medial meniscus. Only the associated lesions were treated (except for ACL lesions) and dislocating anterior horns of the medial menisci were left alone. Follow-up averaged 21 months (7 to 40 months). At follow-up, 11 knees were graded as excellent, 3 as good, and 1 as fair according to the Lysholm scale. Eight knees had minor symptoms and 6 were asymptomatic; no improvement was noted in 1 knee. Overall, 12 patients (14 knees) were satisfied with their treatment. Dislocating anterior horn of the medial meniscus is a normal anatomic variant with little or no clinical significance. When seen during arthroscopy, a significant lesion should be looked for. It is an incidental finding and should be left alone.Arthroscopy 1998 Apr;14(3):246-9     

Impact of Partial and complete rupture of anterior cruciate ligament on medial meniscus: A cadavaric study

Background:

The clinical relationship between medial meniscus tear and anterior cruciate ligament (ACL) rupture has been well documented. However, the mechanism of this clinical phenomenon is not exactly explained. Our aim is to investigate the biomechanical impact of partial and complete ACL rupture on different parts of medial meniscus.

Materials and Methods:

Twelve fresh human cadaveric knee specimens were divided into four groups: ACL intact (ACL-I), anteromedial bundle transection (AMB-T), posterolateral bundle transection (PLB-T), and ACL complete transection (ACL-T) group. Strain on the anterior horn, body part, and posterior horn of medial meniscus were measured under 200 N axial compressive tibial load at 0°, 30°, 60°, and 90° of knee flexion, respectively.

Results:

Compared with the control group (ACL-I), the ACL-T group had a higher strain on whole medial meniscus at 0°, 60°, and 90° of flexion. But at 30°, it had a higher strain on posterior horn of meniscus only. As to PLB-T group, strain on whole meniscus increased at full extension, while strain increased on posterior horn at 30° and on body of meniscus at 60°. However, AMB-T only brought about higher strain at 60° of flexion on body and posterior horn of meniscus.

Conclusions:

Similar to complete rupture, partial rupture of ACL can also trigger strain concentration on medial meniscus, especially posterior horn, which may be a more critical reason for meniscus injury associated with chronic ACL deficiency.     

Anterior cruciate ligament deficiency alters the in vivo motion of the tibiofemoral cartilage contact points in both the anteroposterior and mediolateral directions

BACKGROUND: Quantifying the effects of anterior cruciate ligament deficiency on joint biomechanics is critical in order to better understand the mechanisms of joint degeneration in anterior cruciate ligament-deficient knees and to improve the surgical treatment of anterior cruciate ligament injuries. We investigated the changes in position of the in vivo tibiofemoral articular cartilage contact points in anterior cruciate ligament-deficient and intact contralateral knees with use of a newly developed dual orthogonal fluoroscopic and magnetic resonance imaging technique. METHODS: Nine patients with an anterior cruciate ligament rupture in one knee and a normal contralateral knee were recruited. Magnetic resonance images were acquired for both the intact and anterior cruciate ligament-deficient knees to construct computer knee models of the surfaces of the bone and cartilage. Each patient performed a single-leg weight-bearing lunge as images were recorded with use of a dual fluoroscopic system at full extension and at 15 degrees , 30 degrees , 60 degrees , and 90 degrees of flexion. The in vivo knee position at each flexion angle was then reproduced with use of the knee models and fluoroscopic images. The contact points were defined as the centroids of the areas of intersection of the tibial and femoral articular cartilage surfaces. RESULTS: The contact points moved not only in the anteroposterior direction but also in the mediolateral direction in both the anterior cruciate ligament-deficient and intact knees. In the anteroposterior direction, the contact points in the medial compartment of the tibia were more posterior in the anterior cruciate ligament-deficient knees than in the intact knees at full extension and 15 degrees of flexion (p < 0.05). No significant differences were observed with regard to the anteroposterior motion of the contact points in the lateral compartment of the tibia. In the mediolateral direction, there was a significant lateral shift of the contact points in the medial compartment of the tibia toward the medial tibial spine between full extension and 60 degrees of flexion (p < 0.05). The contact points in the lateral compartment of the tibia shifted laterally, away from the lateral tibial spine, at 15 degrees and 30 degrees of flexion (p < 0.05). CONCLUSIONS: In the presence of anterior cruciate ligament injury, the contact points shift both posteriorly and laterally on the surface of the tibial plateau. In the medial compartment, the contact points shift toward the medial tibial spine, a region where degeneration is observed in patients with chronic anterior cruciate ligament injuries.     

Editorial Commentary: Arthroscopy Is the Gold Standard for Diagnosis of Meniscal Ramp Lesions: Magnetic Resonance Imaging Also May Be Helpful

Identifying and treating medial meniscal ramp lesions in conjunction with ligament reconstruction restores critical stability in knees with ligament injuries. This must begin with obtaining high-quality magnetic resonance imaging (MRI) and critical evaluation of the MRI and include a subsequent thorough arthroscopic examination of these knees. As evident in previous studies, most surgeons associate medial meniscal ramp lesions with anterior cruciate ligament (ACL) tears. Biomechanical studies have reported that a ramp lesion produces significant anterior tibial translation and external rotational instability in ACL-deficient knees that is not reestablished with an isolated ACL reconstruction. In addition, recent research identified ramp lesions in one-third of multiligament knee injuries with an intact ACL and two-thirds of patients with posteromedial tibial plateau bone bruises on MRI. Restoring knee stability and biomechanics is necessary in treating all knee ligament injuries. Don’t miss the meniscal ramp lesion. Have a high index of suspicion, obtain a high-quality MRI,and arthroscopically evaluate the meniscocapsular junction of the medial meniscus, especially if there is a bone bruise seen on MRI.     

Anatomical relationship between insertion sites,tunnel placement,and lateral meniscus anterior horn injury during single and double bundle anterior cruciate ligament reconstructions: A comparative macroscopic and histopathological evaluation in cadavers

PurposeThe influence of tunnel extension outside the anatomical anterior cruciate ligament (ACL) insertion in single-bundle (SB) or double-bundle (DB) ACL reconstruction is unclear. This study aimed to investigate the anatomical relationship between ACL insertion and tunnel extension in SB and DB ACL reconstruction, and the impact of tibial tunnel extension to the insertion of anterior horn of lateral meniscus in terms of injury.MethodsForty-six paired cadaver knees (mean age, 82.7 ± 10.7 years) were used. Right and left knees were used for SB (10 mm) and DB tunnel reaming (6 mm for the anteromedial and posterolateral bundles). Tibial and femoral tunnels were created to aim at the center of the ACL insertion by arthroscopic visualization. The relationship between tunnel extension and ACL insertion was evaluated macroscopically, and there ratio in two groups were compared by chi-square test. Further, the relative risk for meniscus injury based on tunnel placement was estimated. Coronal section of tibia and parallel section to Blumensaat line in femur were prepared to evaluate the relationship among tunnel position, ACL insertion, and anterior horn of the meniscus histologically.ResultsTibial tunnel extension out of the ACL insertion was observed macroscopically in 9 (39.1%) knees of the SB group, and 3 (13.0%) of the DB group (p = 0.045). In femoral tunnels, extension out of the ACL insertion was seen in 8 (34.8%) knees of the SB group and 1 (4.3%) of the DB group (p = 0.011). Partial injuries of the lateral meniscus anterior horn (LMAH) were observed in 5 (21.7%) knees of the SB group and 1 (4.3%) knee of the DB group (p = 0.091). The relative risk for LMAH injury was calculated as 5.0 (odds ratio, 6.1). Microscopically, SB tunnels appeared to expand out of ACL insertion, both in the femur and tibia.ConclusionsThe incidence of tunnel extension out of the ACL insertion in femur and tibia were higher with SB than with DB reconstruction. Furthermore, injury rate of the LMAH in the DB group was lower.     

Three-dimensional knee joint movements during a step-up: Evaluation after anterior cruciate ligament rupture

The three-dimensional motions of the knee were analysed during closed kinetic chain knee extension in 13 patients with unilateral chronic injury of the anterior cruciate ligament. The patients ascended a platform, and serial stereophotogrammetric roentgenograms were exposed from about 100° of flexion to full extension. From a position of about 100° of knee flexion and 20° of internal rotation, the tibia rotated externally during the extension. Almost no tibial adduction or abduction was observed. The tibial intercondylar eminence translated laterally, distally, and anteriorly relative to the femur. In knees with absence of the anterior cruciate ligament, the intercondylar eminence had a more posterior position compared with the contralateral normal knees. The proximal tibia was used as a fixed reference segment to evaluate the anteroposterior translations of a central point in the femoral condyles. The femoral point was more anteriorly displaced in the injured than in the contralateral knees. This difference might reflect increased activity of the hamstrings in the injured knees, because it was most pronounced at 80° of flexion and decreased with increasing extension. In the sagittal plane, the mean helical axis was positioned close to the femoral insertion of the ligament at 80° of flexion and was displaced distally and anteriorly during extension. In the frontal plane, the axis had a transverse direction at 80° of flexion. At close to full extension, the axis was positioned distally in the lateral condyle and proximally in the medial condyle. In the horizontal plane, the helical axes ran slightly more anteriorly in the medial than in the lateral femoral condyle but changed inclination at close to full extension and became almost parallel to the transverse axis.     

内侧半月板后角Ramp损伤在前十字韧带损伤患者中的发生率及影响因素分析

 目的 研究前十字韧带损伤合并内侧半月板后角 Ramp(内侧半月板后角至后内侧关节 囊滑膜移行区域)损伤的发生率, 并分析其影响因素。方法 2002年 4月至 2007年 10月, 采用韧带重 建手术治疗并确诊为前十字韧带损伤的患者 868例, 男 609例, 女 259例;年龄 15~55岁, 平均 25.2岁。根据手术记录以及术中关节镜探查, 筛选其中存在内侧半月板后角 Ramp损伤的病例, 计算其发生率。 按照性别、年龄段及受伤至手术时间分组, 分析 Ramp损伤发生率的影响因素。结果 868例膝关节确诊为前十字韧带损伤并接受韧带重建手术的患者中, 内侧半月板后角 Ramp损伤的患者为 144例, 男 113例, 女 31例;平均年龄 24.7岁。受伤至手术时间平均 29.3个月。 Ramp损伤的发生率为 16.59% (144/868), 伤后 6周、3、6、12、24个月 Ramp损伤的发生率分别为 12.66%、13.51%、13.17%、14.49%、 15.92%;男性发生率为 18.56%(113/609), 女性为 11.97%(31/259), 两者比较差异有统计学意义;30岁以下的患者 Ramp损伤发生率为 21.59%(114/528), 30岁以上者为 8.82%(30/340), 两者比较差异有统 计学意义。结论 内侧半月板后角 Ramp损伤是前十字韧带断裂的常见合并损伤, 其发生率为 16.59%; 伤后 2年内, Ramp损伤的发生率随受伤时间延长明显增加;男性及 30岁以下患者 Ramp损伤发生率明 显增高。     

Anomalous insertion of the medial menisci

Many types of meniscal anomalies have been reported. The authors encountered two cases of anomalous insertion of the anterior horn of the medial menisci to the lateral femoral condyle, which ran up along the course of the anterior cruciate ligament (ACL), but was independent of the ACL. These anomalies were noted during arthroscopic examination and surgery of the ipsilateral knee for a torn discoid meniscus and a patellar fracture. A 34-year-old woman had a horizontal tear of the lateral discoid meniscus. We performed arthroscopic partial meniscectomy of the inner torn portion of the lateral discoid meniscus and contoured it to resemble a normal meniscus. An anomalous insertion of the medial meniscus was found on examination of the joint during surgery. A 32-year-old man had a patellar fracture and we performed reduction under arthroscopy and internal fixation with cannulated screws. The same anomalous insertion of the medial meniscus was also found on examination of the joint during surgery. We report the cases with a review of the literature.Arthroscopy 1998 Jul-Aug;14(5):505-7     

Meniskusersatz durch Hoffaschen Fettkörper-Erste klinische Ergebnisse

Between December 1986 and July 1988 a replacement of the absent medial, meniscus was taken by means of the infrapatellar adipose body in seven patients. A replacement of the anterior cruciate ligament by means of the middle one third of the patellofemoral ligament was taken too. This operation was done for reconstruction, of the synergism between the anterior cruciate ligament and the posterior horn of the medial meniscus. All patients are controlled in our special knee outpatient service. There were no complication postoperatively and on all seven patients a control arthroscopy was performed twelve months postoperatively. The subjective results are very satisfying because of the restoration of knee stability. The arthroscopic controls of the meniscal replacements, however, showed a reduction in size of the transplants after one year, the tissue was weak and not identical to that of a normal meniscus. Autologous strong tissue, e.g. quadriceps tendon, may have better presuppositions for meniscal replacement.     

A biomechanical evaluation of the Lenox Hill knee brace

This study was conducted to determine the effectiveness of the Lenox Hill knee brace in limiting anterior translation and external rotation of the tibia in reference to the femur in normal and ligament-deficient knees. Four fresh cadaver knees were fitted with Lenox Hill knee braces according to the manufacturer's guidelines. A computer-assisted testing apparatus was constructed that allowed each knee to be tested as a function of knee flexion angle, joint load, and soft tissue integrity. Each knee served as its own control. While 45 kg of anterior force was applied to the tibia of the anterior cruciate ligament deficient knees, the Lenox Hill knee brace was able to decrease anterior translation from an average of 10 mm, to 5.7 mm, at 30 degrees of flexion when no vertical load was present. This limiting effect was lost when the medial collateral ligament was sectioned in addition to the anterior cruciate ligament or when both the medial and the lateral collateral ligaments were sectioned along with the anterior cruciate ligament. When 20 Newton-meters (Nm) of torque was applied to the femurs at 30 degrees of flexion without vertical load, the Lenox Hill knee brace limited external rotation of the tibia in all tested categories. For intact knees at 30 degrees of flexion and no vertical load, the Lenox Hill knee brace decreased external rotation from 18 degrees to 10 degrees. In the anterior cruciate ligament-sectioned knees, external rotation was decreased from an average of 20.2 degrees to 16.1 degrees. In the knees with sectioned anterior cruciate and medial collateral ligaments, the average reduction was from 21.2 degrees to 15.4 degrees.(ABSTRACT TRUNCATED AT 250 WORDS)     

Bilateral Discoid Medial Menisci

Summary: This article adds 2 more cases of bilateral discoid medial menisci to the previously reported 9 cases. The radiographs of the first case revealed bilateral cupping of the medial tibial plateaus and a small lytic lesion of the left distal medial femoral metaphysis. Beside the posteriorly unstable incomplete type discoid medial meniscus, the left knee had several associated arthroscopic findings: depression of the medial tibial plateau with exposed subchondral bone, anomalous insertion of the anterior horn of the discoid meniscus to the anterior cruciate ligament, a pathological medial plica, and longitudinal deep fissures in the trochlea. The second case was a complete type with peripheral horizontal cleavage tears. Following arthroscopic surgery, magnetic resonance imaging (MRI) scans of the contralateral knees were obtained in both cases to search for bilaterality. MRI revealed discoid medial menisci in the unoperated knees as well. The short-term results of arthroscopic meniscectomy may not be as satisfactory as those reported for normal menisci.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 16, No 1 (January-February), 2000: pp 96–101     

The early treatment of motion complications after reconstruction of the anterior cruciate ligament.

The use of active and passive knee motion in the immediate postoperative period and a treatment plan for early postoperative limitations in knee motion has proven highly effective in restoring motion after anterior cruciate ligament (ACL) reconstruction. Of 207 knees, 189 (91%) regained a full range of motion of 0 degrees-135 degrees. The remaining 18 knees (9%) did not regain motion as rapidly as the others and were placed in an early postoperative phased treatment program. Six knees had serial extension casts, nine had early gentle manipulation under anesthesia, and three had arthroscopic lysis of intraarticular adhesions and scar tissue. Fourteen of these 18 knees regained a full range of knee motion. Two of the remaining four knees lacked 5 degrees of full extension, whereas the other two, in patients who had failed to follow medical advice and the rehabilitation program, had permanent and significant limitation of motion. The incidence of postoperative motion problems was related to the extent of the surgical procedure. The incidence was 4% in patients who had only ACL reconstruction, 10% in cases in which added lateral extraarticular procedure had been done, 12% where a meniscus repair had been done, and 23% where a medial collateral ligament repair was done.     

关节镜下前交叉韧带重建后内侧和外侧半月板同期移植术

目的 探讨全关节镜下前交叉韧带重建后内侧和外侧半月板同期移植的微创手术技术.方法 2008年8月对1例实施膝关节双束双通道前交叉韧带重建、内侧和外侧半月板切除的患者,在关节镜下实施内侧和外侧半月板同期移植微创手术.内侧半月板移植采用前后角骨栓固定方法,外侧半月板移植采用前后角骨桥固定方法.术后结果采用VAS疼痛评分、Cysholm评分和国际膝关节评分委员会(IKDC)分级评价.关节稳定性检查包括Lachman试验、抽屉试验和轴移试验.结果 术后随访26个月,患者膝关节屈曲、伸直和负重行走功能正常.VAS膝关节疼痛评分较术前降低2分,Lysholm评分较术前升高20分.IKDC分级由术前C级上升到B级.膝关节稳定性检查基本正常.术后1年MRI检查显示,重建前交叉韧带连续性完整,内侧和外侧移植异体半月板外形均较好,内侧半月板后角和外侧半月板前角有轻微萎缩.术后18个月关节镜复检观察到,外侧和内侧移植半月板均愈合良好,形态完整,但前角表面均有轻度磨损现象.结论 对膝前交叉韧带损伤和内、外侧半月板切除的患者,在前交叉韧带重建术后同期实施内侧和外侧半月板移植术可以尽量恢复膝关节的稳定性和力学平衡,对年轻患者是可供选择的治疗方式.术中建议采用同一供体的内侧和外侧异体半月板,制作各骨道时须注意其方向以避免骨道相互交通.

Abstract：

Objective 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.Methods 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 menicectomy 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.Results 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.Conclusions 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.     

Usefulness of knee arthroscopy for diagnosis of knee pain in pediatric patients: comparison with preoperative clinical diagnosis

Purpose

To investigate the knee arthroscopic findings of pediatric patients with knee pain.

Subjects

Ninety-five knees of 94 patients (46 males and 48 females) aged 15 years or younger who underwent knee arthroscopy during a 4-year period from January 2007 were studied. The mean age at surgery was 13.5 (7–15) years. The mean interval from symptom onset to arthroscopic examination was 6.8 months (5 days to 2 years 10 months).

Results

The most common cause of knee pain was sports-related activities (64 knees). Other causes included falling from a moving bicycle (5 knees), while knee pain appeared with no defined reason in 14 knees. The most frequent final diagnosis based on knee arthroscopic findings was anterior cruciate ligament (ACL) injury (35 knees), followed by discoid lateral meniscus (16 knees), lateral meniscal tear (11 knees), and medial plica syndrome (9 knees), while no arthroscopic abnormality was observed in 8 of 95 knees. Among the 95 knees, the diagnosis based on preoperative physical tests and imaging findings was different from the arthroscopic diagnosis in 16 knees, 8 of which were diagnosed preoperatively as medial meniscal tear.

Conclusion

ACL injury and discoid lateral meniscus were the predominant conditions in pediatric patients who underwent knee arthroscopic surgery for knee pain. Knee arthroscopy is useful to provide a definitive diagnosis for knee pain in pediatric patients. Preoperative evaluations had a diagnostic accuracy of only 83.2 % and failed to diagnose conditions such as medial plica syndrome and chondral injury. Therefore, diagnosis before knee arthroscopy has to be interpreted with caution.     

前交叉韧带胫骨止点撕脱骨折关节镜下骨与周围组织损伤分级及其意义

目的提出前交叉韧带胫骨止点撕脱骨折关节镜下骨与周围组织损伤分级,分析其与Meyers-McKeever分型的一致性,为术前精准评估及治疗方案选择提供指导。方法前交叉韧带胫骨骨性止点及足印为D区,以此为中心,前内侧区域包括内侧半月板前部及膝横韧带内侧部为A区;前外侧区域包括外侧半月板前角及膝横韧带外侧部为B区;后方区域包括外侧半月板后角、内侧半月板后角为C区。关节镜分级:1级为D区不完全损伤,A、B、C区不涉及软组织损伤;2级为D区完全损伤,A、B、C区任意1区或2区存在软组织损伤;3级为D区完全损伤,同时A、B、C区均存在软组织损伤。纳入42例单侧急性前交叉韧带胫骨止点撕脱骨折,4名评估者分别进行关节镜下分级与Meyer-McKeever分型,比较评估者之间一致性。结果评估者对所有患者进行Meyer-McKeever分型与关节镜分级时具有较高的一致性(评估者1的Kappa值为0.804,评估者2的Kappa值为0.809,评估者3的Kappa值为0.808,评估者4的Kappa值为0.712)。结论前交叉韧带胫骨止点撕脱骨折的关节镜分级与Meyer-McKeever分型一样可靠,术前可通过二者的一致性准确预判骨折及其周围组织损伤情况,从而正确指导治疗方案选择。     

Medial and lateral segond fractures in a skeletally immature patient: a radiographic marker for the multiply injured knee

Marginal fractures of the medial tibial plateau have been reported in the literature as a secondary type of Segond fracture. Some reports described this entity in the setting of combined injuries such as root avulsions of the medial meniscus, complete disruption of the posterior cruciate ligament (PCL), partial tear of the anterior cruciate ligament (ACL), and tears of the medial meniscus and medial collateral ligament. It has been postulated that medial marginal fractures are secondary to compression of the medial aspect of the femoral condyle and tibial plateau with a corresponding posterolateral corner injury. However, this mechanism of injury may not always be as straightforward.This article presents a case of an alternate injury pattern in a skeletally immature patient. A 16-year-old boy sustained a varus force and twisting injury to his knee, resulting in radiographic evidence of multiple avulsion fractures of the knee, including a fibular epiphyseal avulsion fracture and medial and lateral Segond fractures. Usually, the avulsion fractures serve as markers for significant ligamentous injuries in adult patients, but our patient had minimal injury to the PCL, ACL, and posterolateral corner. Further physical examination and imaging studies revealed an anterior horn root avulsion, meniscocapsular separation, and anterior cortical rim fracture. A combination of imaging modalities helped us further characterize the injury pattern to devise the optimal surgical plan, especially the fixation of the anterior cortical fracture of the tibia.     

Total knees designed for normal kinematics evaluated in an up‐and‐down crouching machine

We constructed a crouching machine to study the motion of the knee joint, in which a motor was used to wind the quadriceps tendon so as to move the knee from high flexion to extension and back into flexion, while springs simulated hamstrings forces. Seven human cadaveric knees were tested intact and then after anterior cruciate ligament (ACL) resection. Motions of the femur, tibia, and patella were recorded by an optical tracking system. We then inserted plastic models representing commonly used total condylar and posterior stabilized knee replacement designs. Femoral motion was described by successive positions of the transverse axis of the femur projected onto the tibial surface. In the knee replacements, motions were similar to that of an ACL‐deficient knee. We then tested two new designs with features intended to prevent anterior paradoxical sliding and to promote a medial pivot motion with femoral rollback primarily on the lateral side. The motion path more closely followed that of the normal intact knee. We concluded that motion guiding features in a total knee replacement could reproduce a normal neutral path that might result in functional improvements for the patient. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27: 1022–1027, 2009     

Posterior root tear fixation of the lateral meniscus combined with arthroscopic ACL double-bundle reconstruction: technical note of a transosseous fixation using the tibial PL tunnel

According to our observation in ACL reconstruction, we find root tears of the posterior horn of the lateral meniscus as a common concomitant injury in ACL-deficient knees. This might be a consequence of initial trauma or of the increased anterior–posterior translation of the tibia and an overload impact on the posterior meniscus root in ACL-deficient knees. A tear of the posterior horn of the medial meniscus causes a 25% increase in peak pressure in the medial compartment compared with that found in the intact condition. The repair restores the peak contact pressure to normal (Allaire et al. in J Bone Joint Surg Am 90(9):1922–1931, [2008]). A tear of the posterior horn of the lateral meniscus might have similar consequences. We hypothesize the surgical anatomical reattachment of the root at the tibia helping to restore knee joint kinematics and helping to advance ACL-graft function. This article presents an arthroscopical technique to reattach the posterior meniscus root in combination with ACL double-bundle reconstruction. The procedure uses the tibial PL tunnel to fix the meniscus suture.     

Combined Injury to the ACL and Lateral Meniscus Alters the Geometry of Articular Cartilage and Meniscus Soon After Initial Trauma

Combined injury to the anterior cruciate ligament (ACL) and meniscus is associated with earlier onset and increased rates of post-traumatic osteoarthritis compared with isolated ACL injury. However, little is known about the initial changes in joint structure associated with these different types of trauma. We hypothesized that trauma to the ACL and lateral meniscus has an immediate effect on morphometry of the articular cartilage and meniscus about the entire tibial plateau that is more pronounced than an ACL tear without meniscus injury. Subjects underwent magnetic resonance imaging scanning soon after injury and prior to surgery. Those that suffered injury to the ACL and lateral meniscus underwent changes in the lateral compartment (increases in the posterior–inferior directed slopes of the articular cartilage surface, and the wedge angle of the posterior horn of the meniscus) and medial compartment (the cartilage-to-bone height decreased in the region located under the posterior horn of the meniscus, and the thickness of cartilage increased and decreased in the mid and posterior regions of the plateau, respectively). Subjects that suffered an isolated ACL tear did not undergo the same magnitude of change to these articular structures. A majority of the changes in morphometry occurred in the lateral compartment of the knee; however, change in the medial compartment of the knee with a normal appearing meniscus also occurred. Statement of clinical significance: Knee injuries that involve combined trauma to the ACL and meniscus directly affect both compartments of the knee, even if the meniscus and articular cartilage appears normal upon arthroscopic examination. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:759-767, 2020