The reference point to measure the anterior intermeniscal ligament's thickness: an MRI study

The purpose of this study was to identify a reliable reference point for measuring anterior intermeniscal ligament thickness and to investigate the morphological characteristics of the ligament at its attachment site to anterior horns of both menisci by MRI. MRI was performed in 98 knees of randomly chosen patients. The anterior intermeniscal ligament was detected in 61 knees (62.2%). The average ligament length was 29.8 mm. Men had significantly longer anterior intermeniscal ligament than women patients (32.5 vs. 27.8 mm). The thickness of anterior intermeniscal ligaments at their attachment sites to menisci was usually less than 3 mm; a thickness of 3 mm or more at the attachment site to anterior horns of the meniscus was defined as "cordlike." It is suggested that the "cordlike" pattern is a variation of the anterior intermeniscal ligament's attachment characteristics, and that this might have a significant role in meniscal translations during knee motion, and also that the "cordlike" pattern could be clinically important with respect to its relationship to the anterior horn of medial meniscus. The attachment site of the ligament is a reliable reference point for measuring its thickness.     

MR imaging of the anterior intermeniscal ligament: classification according to insertion sites

Our objective was to study the frequency of anterior intermeniscal ligament on MR imaging and to make a classification according to its insertion sites on MR images. Sagittal T1-weighted and thin-section transverse T2*-weighted MR images of the knee were prospectively evaluated in 229 subjects without significant synovial effusion or total rupture of the anterior cruciate ligament. By using thin-section transverse images, the ligament was classified into three types according to its insertion sites (type A: between anterior horns of medial and lateral menisci; type B: between anterior horn of medial meniscus and anterior margin of lateral meniscus; type C: between anterior margins of medial and lateral menisci). On sagittal images location of the ligament was determined with respect to a line drawn between anterior of the tibial epiphysis and posterior of the intercondylar notch to look for a relation between its type on transverse images and location on sagittal images. Separately, arthroscopy was made in 36 patients to verify the MR assessment of the presence of the ligament. Anterior intermeniscal ligament was found in 53% of the subjects. Type B was the most common group (58%). Magnetic resonance imaging has a sensitivity and a specificity of 67 and 100%, respectively, in the detection of the ligament. Types A and C had a statistically significant location posterior and anterior, respectively, to the master line on sagittal images. In arthroscopy, the ligament was either cord-like (67%) or flat (33%) in appearance. Routine sagittal MR images can help identify anterior intermeniscal ligament.     

The biomechanical interdependence between the anterior cruciate ligament replacement graft and the medial meniscus

To establish a quantitative biomechanical relationship between the anterior cruciate ligament graft and the medial meniscus, 10 human cadaveric knees were examined using the robotic/universal force-moment sensor testing system. In response to a combined 134-N anterior and 200-N axial compressive tibial load, the resulting kinematics of the knee and the in situ forces in the anterior cruciate ligament, the anterior cruciate ligament graft, and the medial meniscus were measured. Anterior tibial translation significantly increased after anterior cruciate ligament transection, between 6.8 +/- 2.3 mm at full extension and 12.6 +/- 3.3 mm at 30 degrees of flexion. Consequently, the resultant forces on the medial meniscus, ranging from 52 +/- 30 N to 63 +/- 51 N between full extension and 90 degrees of knee flexion in the intact knee, were doubled as a result of anterior cruciate ligament deficiency. However, after anterior cruciate ligament reconstruction, anterior tibial translations were restored to the levels of the intact knee, and thus the forces on the medial meniscus were restored as well. Likewise, the in situ forces in the anterior cruciate ligament replacement graft increased between 33% and 50% after medial meniscectomy.     

Force displacement characteristics of the posterior cruciate ligament.

The percent force changes in the posterior cruciate ligament were calculated using a previously validated computerized knee model after the femoral insertion sites were varied 2.5 and 5.0 mm in an anterior, posterior distal, anterior distal, and posterior distal direction. The tibial insertion sites were also varied 2.5 and 5.0 mm in the medial, lateral, proximal, and distal directions. Percent force changes were measured over a range of 0 degree to 90 degrees. These insertion sites simulated potential surgical placement errors. Results of this study demonstrated that the greatest percent force changes in the posterior cruciate ligament were at full extension. The greatest absolute percent force change between 0 degree and 90 degrees of flexion was with a femoral insertion of the posterior cruciate ligament placed 5 mm anterior to its normal attachment site, which resulted in a 39% change in the posterior cruciate ligament force. Distal femoral site attachment had the least effect (10% at 5.0 mm). Alterations at the tibial attachment site were less sensitive than on the femur; the greatest absolute percent force changes occurred with medial and lateral attachment sites (14% and 15%, respectively, at 5.0 mm). A minimal amount of percent force changes were seen between 45 degrees and 75 degrees of knee flexion in all positions tested for both tibial and femoral attachment sites. This model suggests that, like the anterior cruciate ligament, the force in the posterior cruciate ligament is also sensitive to attachment site position. As in anterior cruciate ligament studies, the femoral attachment site was found to be more sensitive.(ABSTRACT TRUNCATED AT 250 WORDS)     

Reproducibility of anatomic tibial landmarks for anterior cruciate ligament reconstructions.

We evaluated the reproducibility of landmarks used for accurate anatomic placement of the tibial tunnel in anterior cruciate ligament reconstruction. Landmarks evaluated were the medial tibial eminence, the posterior cruciate ligament, the "over-the-back" position, the true posterior border of the tibia, and the posterior border of the lateral meniscus. Forty-two pairs of cadaveric knees were dissected, and anatomic measurements were made regarding the anterior cruciate ligament insertion and these various landmarks. Statistical analysis was used to confirm reproducibility and significance. Measurements based on the medial tibial eminence and posterior border of the meniscus were particularly erratic. The most reproducible anatomic landmark was the posterior cruciate ligament. The anterior border of the posterior cruciate ligament was consistently 6.7 mm posterior to the posterior border of the anterior cruciate ligament and 10.9 mm posterior to the central sagittal insertion point of the anterior cruciate ligament. The over-the-back position was consistently in contact with the anterior border of the posterior cruciate ligament if the knee was flexed with a posterior-directed force applied. In this position, the over-the-back position was equally reproducible as compared with the posterior cruciate ligament. Measurements gauged from the true posterior border of the tibia gave a second rigid bony landmark but with a wider standard deviation than the posterior cruciate ligament-based landmarks. The relative anterior-posterior dimension of the tibia did not correlate with the relationship between the anterior cruciate ligament and other anatomic landmarks.     

Injury patterns to the posteromedial corner of the knee in high-grade multiligament knee injuries: a MRI study

Injury patterns to the posteromedial corner of the knee have not been previously studied in the context of multiligament knee injuries. We performed a retrospective magnetic resonance imaging and clinical review of a consecutive series of 27 dislocatable knees presenting to a single level-one trauma center from 2005 to 2008. Post-injury magnetic resonance imaging studies were reviewed by two fellowship-trained musculoskeletal radiologists to assess injury patterns to the posteromedial corner. In our series, injury to at least one structure within the posteromedial corner was observed in 81% (22/27) of cases while injury to the superficial medial collateral ligament alone was seen in 63% (17/27) of cases. Furthermore, injuries to the posterior horn of the medial meniscus were associated with a tear of the meniscotibial ligaments in all cases and with a tear of the posterior oblique ligament in 67% of cases. All patients with grade III laxity (>10 mm medial opening) under an examination under anesthesia had a complete tear of the posterior oblique ligament and meniscotibial ligament in addition to a medial collateral ligament injury. Injury to the semimembranosus attachment alone was not associated with clinically significant laxity under an examination under anesthesia. Our findings demonstrate that injuries to the posteromedial corner are common in the setting of traumatic knee dislocations. Interestingly, high-grade medial instability during an examination under anesthesia and injury to the posterior horn of the medial meniscus may be important indicators for further posteromedial corner injury.     

Factors affecting meniscal extrusion: correlation with MRI, clinical, and arthroscopic findings

The existence of meniscal extrusion is well known in the natural history of the osteoarthritic knee. However, extruded menisci are also seen in non-pathologic knees. To ascertain the prevalence of meniscal extrusion in non-arthritic patients, the MRIs of 100 knees were prospectively studied. The data were correlated both with clinical and operative arthroscopic findings. The results showed 68.5% of the medial menisci to have some degree of extrusion, averaging at 28% of the meniscal size. While the lateral meniscus were extruded in 18.8% of cases at an average of 15% of the meniscal size. Furthermore, a relationship between the anterior insertion variant of the anterior medial meniscus and meniscal extrusion was found (P=0.001) in this series. The results suggest meniscal extrusion to be much more common in non-arthritic knees than previously estimated. The results also suggest that when the anterior horn of the medial meniscus inserts anteriorly in the tibial plateau, the meniscus tends to be extruded. It must be kept in mind that one of the limitations of this work is that the MRIs are taken in a non-weightbearing position.     

Radiographic guided drilling of bony tibial tunnels for fixation of meniscus transplants using percentage references

The objective of our investigation was to evaluate the precision of radiographic-guided tibial tunnel drilling for anatomical anchoring of meniscus transplants at the tibial insertion areas. In 20 cadaveric proximal tibiae, the meniscal insertions were dissected and their circumferences outlined. Standardized photographs of the tibial plateau were obtained. Applying established percentage values for radiographic determination of the meniscus insertion midpoints, tibial tunnels were drilled using a standard ACL-guide. Guide positioning was performed by using the midpoints as determined on standard AP and lateral radiographs. After tibial tunnel drilling, a second set of standardized photographs of the tibial plateau was obtained. Digital imaging permitted the superposition of pre- and postoperative images. Overlapping between the anatomical insertion areas and the tibial tunnel exit was determined, as well as the distance between the borders of the insertion areas and the tunnel exit. Insertion area and tunnel exit showed a mean overlapping of 59.8 ± 34.8% (anterior horn), respectively 62.4 ± 32.0% (posterior horn) for the lateral meniscus and of 88.4 ± 15.5% (anterior horn), respectively 60.3 ± 31.6% (posterior horn) for the medial meniscus. Mean distance between the borders of insertion area and tunnel exit was 2.0 ± 1.5 mm (anterior horn), respectively 2.0 ± 1.7 mm (posterior horn) for the lateral meniscus and 0.9 ± 0.9 mm (anterior horn), respectively 2.1 ± 1.4 mm (posterior horn) for the medial meniscus. Thus, a precise drilling of tibial tunnels at the anatomical insertions of the menisci can be obtained by positioning a standard ACL-guide under radiographic control in a cadaver setting. In advanced day-by-day clinic, this knowledge could facilitate the surgical technique for anatomical fixation of lateral and medial meniscus transplants.     

Tibial attachment area of the anterior cruciate ligament in the extended knee position

Knowledge of the anatomy of the anterior cruciate ligament (ACL), including its course and orientation in relation to the roof of the intercondylar fossa, is a prerequisite for successful intra-articular ACL reconstruction. To attain precision placement of the tibial attachment site and to avoid graft/roof conflict in the extended knee position, we assessed the anteroposterior tibial insertion of the ACL in the midsagittal plane of the extended knee. We measured the anterior-posterior (AP) limits and the center of the tibial attachment area of the ACL from the anterior tibial margin. The inclination angle of the intercondylar fossa roof was measured with respect to the shaft axis of the femur. The tibial attachment area of the ACL was determined in ten cadaveric knees. Using the cryoplaning technique, we determined the tibital attachment of the ACL in five knees. Using contrast magnetic resonance arthrography (MRA), we measured the tibial insertion of the ACL in 35 patients (23 male and 12 female) with intact ACLs. The total AP midsagittal diameter of the tibia averaged 51.0±5.8 mm in the cadaveric knees, 49 mm on cryosections, and 53.7 mm in men and 49.0 mm in women with MRA. The average anterior limit of the ACL, measured from the anterior tibial margin, was 14±4.2 mm in the cadaveric knees, 12.1 mm at cryosectional anatomy, and 15.2 mm in men and 13.4 mm in women with MRA. The center of the tibial attachment area was located at 21±2.6 mm in cadaveric knees, at 21.2 mm on cryosections, and at 23.7 mm in men and at 21.4 mm in women with MRA. The posterior limit of the tibial attachment area of the ACL was 29.0±4.1 mm in cadaveric knees, 30.6 mm on cryosections, 32.1 mm in male and 29.4 mm female patients with MRA. The roof inclination angle measured on average 39.8° on cryosections and 36.8° in men and 35.2° in women on MRA. Based on these morphometric data and to avoid notch/graft conflict in knee extension, we advocate placing the center of the tibial tunnel at 44% of the tibia diameter posterior and parallel to the individual intercondylar roof inclination angle.     

关节镜下膝关节腘肌腱重建的实验研究

目的:进一步研究膝关节后外复合体(posterolateral complex,PLC)与腘肌复合体的解剖特点,设计关节镜下重建腘肌腱的手术方法.方法:通过10例成人膝关节尸体标本进行两部分研究,每部分各取5例标本:第一部分进行大体解剖研究,对腘肌复合体(包括腘肌腱、肌腹、股骨附着点、肌腱-肌腹交界区)的解剖特点以及周围相邻解剖结构(包括胫骨平台、外侧半月板后角、后交叉韧带、胭腓韧带、血管)进行观察和测量.第二部分进行关节镜下手术重建技术的流程设计.设计显露腘肌腱的股骨附着点和肌腱-肌腹交界点的关节镜入路以及股骨和胫骨隧道的定位与制备方法,引入移植物并固定,完成腘肌腱的重建.结果:第一部分:腘肌腱的股骨附着点位于滑膜反折区,属滑膜外结构;止于股骨的腘肌腱沟的最近端,与关节软骨边缘紧邻,与外侧副韧带股骨附着点中心相距1.5～1.6cm.腘肌腱走行于腘肌腱浅沟内、肌腱-肌腹交界点位于胫骨后外侧平台的内、外中线与关节软骨面远侧1.0cm线的交点上,内侧距离后交叉韧带外侧边缘1.2～2.0cm、外侧与上胫腓关节的内侧缘紧邻.第二部分:进行膝关节镜下手术操作.采用前外入路及外侧辅助关节镜入路切除腘肌腱近端附着点周围滑膜反折,显露整个附着区,并利用克氏针确定中心点,自外向内制备股骨隧道.通过后外、后内及穿后间隔关节镜入路,沿腘肌腱走行局部切开与后关节囊的结合部,显露肌腱-肌腹交界点,并利用前交叉韧带重建胫骨导向器定位,自Gerdy结节向该交界点制备前后方向胫骨骨隧道.将移植物引入两隧道,并用挤压螺钉固定.5例标本手术均获成功,移植物可有效控制外旋稳定性.结论:根据解剖研究确定腘肌腱远近端的定位标志,通过关节镜技术进行显露及定位,在关节镜下完成腘肌腱的重建手术具有可行性.     

Transverse ligament and its effect on meniscal motion. Correlation of kinematic MR imaging and anatomic sections.

RATIONALE AND OBJECTIVES: To evaluate the effect of the transverse ligament on translation of the menisci. METHODS: Six cadaveric knees were examined by MR imaging inside a positioning device before and after transecting the transverse ligament. The knees were examined at various positions: extension, 30 degrees of flexion, 60 degrees of flexion, and full flexion. Sagittal T1-weighted spin-echo images were generated at each knee position and evaluated for statistical differences with regard to anterior-posterior meniscal excursion. RESULTS: Statistically significant differences in meniscal excursion were found before and after transsecting the transverse ligament for anterior-posterior meniscal motion of the anterior horn of the medial meniscus at 30 degrees of knee flexion. No such significant differences were found, however, at 60 degrees of flexion and full flexion in anterior-posterior meniscal excursion of the anterior or posterior horn of either meniscus before and after transsecting the transverse ligament. CONCLUSIONS: The transverse ligament has a restricting effect on anterior-posterior excursion of the anterior horn of the medial meniscus at lower degrees of knee flexion.     

Anomalous insertion of the medial meniscus into the anterior cruciate ligament: the MR appearance

The aim of this study was to determine the characteristic MR findings of the anomalous insertion of the medial meniscus (AIMM) into the anterior cruciate ligament (ACL), and to document potential pitfalls in its interpretation. We reviewed 1326 consecutive knee arthroscopic studies to identify patients with an AIMM. 30 knees of 26 patients (4 females, 22 males; average age, 31.3 years; range, 14-50 years) were included in this study. We evaluated the presence of an AIMM and analysed the MR findings, including the ACL attachment sites of the AIMMs, the absence of the transverse ligament, meniscal tears and a discoid meniscus. AIMMs were detected by MR imaging in 16 knees of 18 patients (60%, 18/30). The AIMMs showed a linear band with low signal intensity on T2 weighted sagittal images running parallel to the ACL. The AIMMs were inserted into the lower portion of the ACL in eight knees, the middle portion in five knees, and the intercondylar notch in five knees. Meniscal tears (10 medial, 10 lateral) were found in 20 knees of 16 patients. Six knees of five patients showed a discoid meniscus. 15 knees of 14 patients showed no transverse ligament on MR imaging. An AIMM has the potential to be misinterpreted as a meniscal tear, ACL tear or infrapatellar plica on knee MR imaging. Familiarity with the characteristic MR findings can aid in the detection of an AIMM into the ACL.     

Anterior rim tibial plateau fractures and posterolateral corner knee injury

The aim of this study was to review MRI findings of clinically suspected posterolateral corner knee injuries and their associated internal derangements. Sixteen knees in 15 patients who had evidence of a posterolateral corner knee injury on the physical exam underwent MRI to evaluate the posterolateral corner of the knee and to look for associated injuries. Two musculoskeletal radiologists reviewed the scans. Surgery was performed on 10 of the knees. Tibial plateau fractures were present in 6 knees; 5 of the fractures were anteromedial rim tibial plateau fractures. The popliteus muscle was injured in 13 knees and the biceps femoris in 6 knees. The lateral collateral ligament was ruptured in 12 knees. The posterior cruciate ligament was completely ruptured in 7 knees and avulsed from its tibial attachment in 1 knee. Eleven knees had a complete anterior cruciate ligament rupture. The anterior cruciate ligament was edematous without complete disruption of all fibers in 3 knees. There was excellent correlation between the MRI results and operative results in regard to the presence of a posterolateral corner injury of the knee (9 of the 10 knees had a posterolateral corner injury). In our study MRI readily detected posterolateral corner injuries. Posterolateral corner injuries of the knee are frequently associated with a variety of significant injuries, including cruciate ligament tears, meniscus tears, and fractures. Fractures of the peripheral anteromedial tibial plateau are not common; however, given their relatively common occurrence in this study, they may be an indicator of a posterolateral corner injury to the knee.     

Usefulness of 99Tcm-MDP knee SPET for pre-arthroscopic evaluation of patients with internal derangements of the knee

The aim of this study was to ascertain whether knee SPET can localize lesion sites in patients with internal derangements of the knee. We performed knee SPET as a pre-arthroscopic examination in 63 consecutive patients. SPET imaging was performed with a triple-headed SPET camera 4 h after the injection of 99Tcm-methylene diphosphonate. Arthroscopic diagnoses were as follows: 28 medial meniscus injuries, 24 lateral meniscus injuries, 31 anterior cruciate ligament (ACL) injuries, three posterior cruciate ligament injuries and one medial collateral ligament injury. Of 30 patients with crescent-shaped increased activity at the medial tibial plateau, 22 had medial meniscus injuries (positive predictive value: PPV 73%); of 17 patients with crescent-shaped activity at the lateral tibial plateau, 13 had lateral meniscus injuries (PPV 76%). Of 18 patients with increased activity at ACL attachment sites (primary sign), 17 had ACL injuries (PPV 94%). Of 27 patients with increased activity at bone impaction sites of ACL injury (secondary sign), 22 had ACL injuries (PPV 81%). Of 32 patients who had either a primary or secondary sign, 26 had ACL injuries (PPV 81%). We conclude that knee SPET is very useful in the management of internal derangements of the knee, particularly in determining the need for arthroscopy by localizing lesion sites.     

MR imaging of the knee: position related changes of the menisci in asymptomatic volunteers

RATIONALE AND OBJECTIVES: To evaluate position related changes of the menisci in asymptomatic volunteers based on MR imaging of the knee in different positions. METHODS: Twenty-two knees from 22 asymptomatic volunteers with no history of knee injury and no evidence of meniscal tears were examined with a 0.5-T open-configuration MR system. Sagittal and coronal images were obtained with the knee supine in neutral, supine in 90-degree flexion with external and internal rotation, as well as in upright weight-bearing positions. The position of the menisci from the outer inferior edge of the meniscus to the outermost edge of the articular cartilage of the tibial plateau was measured, and meniscal movement was calculated. The Wilcoxon signed-rank test was used for statistical analysis. RESULTS: Meniscal movement in the sagittal plane was greatest in the anterior horn of the medial meniscus upon position change from supine neutral to supine in 90-degree flexion with external rotation (mean, 10.5 millimeters). The least meniscal movement was observed in the anterior horn of the lateral meniscus when changing from the supine neutral to the upright knee position (mean, 0.6 millimeters). Meniscal protrusion (ie, protrusion of any part of the meniscus beyond the tibial plateau) was noted most frequently for the anterior horn of the medial meniscus (14/22 instances; 63.6%) in the sagittal plane with the knee in neutral position (mean, 2.6 millimeters, range, 1.8-2.8 millimeters). In the coronal plane, medial meniscal protrusion was most frequently present in the upright weight-bearing position (11/22 instances (50%; mean, 2 millimeters; range, 1.2-2.6 millimeters). CONCLUSIONS:: Meniscal movement is most prominent in the anterior horn of the medial meniscus with the knee in the supine position in 90-degree flexion with external rotation. Meniscal protrusion is more frequently present in the medial meniscus and averaged less than 3 millimeters in normal volunteers in either the sagittal or coronal MR imaging plane.     

High tibial osteotomy and ligament reconstruction for varus angulated anterior cruciate ligament-deficient knees

In a consecutive series, we treated 41 young patients who had anterior cruciate ligament deficiency, lower limb varus angulation, and varying amounts of posterolateral ligament deficiency. Seventy-three percent of the patients (N = 30) had lost the medial meniscus and 63% (N = 26) had marked articular cartilage damage in the medial compartment. All patients were treated with high tibial osteotomy and, in the majority (N = 34), anterior cruciate ligament reconstruction a mean of 8 months later. Posterolateral reconstructions were also required in 18 knees. A 100% follow-up was obtained at a mean of 4.5 years after osteotomy. Gait analysis testing was done in 17 knees before and after osteotomy. At follow-up, a reduction in pain was found in 71% (29 knees); elimination of giving way, in 85% (35 knees); and resumption of light recreational activities without symptoms, in 66% (27 knees). The patient rating of the knee condition was normal or very good in 37% (15 knees) and good in 34% (14 knees). The mean Cincinnati Knee Rating Score significantly improved from 63 to 82 points. The mean adduction moment, 35% higher than controls preoperatively, significantly decreased to below normal values postoperatively. Correction of varus alignment was maintained in 33 knees (80%). We recommend osteotomy in addition to ligament reconstructive procedures in these knees with complex injury patterns.     

Evaluation of the size and position of the insertion of the anterior medial meniscus root in varus osteoarthritic knees

Purpose

Recent studies have suggested radial displacement of the medial meniscus as a cause of varus knee osteoarthritis (OA). Two anatomical studies reported that such displacement may be associated with anterior insertion of the medial meniscus anterior horn. It was aimed to evaluate the location and area of this insertion in patients with advanced knee OA.

Methods

Medial meniscus anterior horn insertions were classified into four types, as described in a previously reported classification during 225 total knee arthroplasty (TKA) in 184 patients. The incidence rates of insertion type were compared with previously reported rates in nearly normal or non-arthritic knees. The insertion surface area was also measured during 158 TKAs.

Results

Of the 225 knees, 82 (36.4 %), 93 (41.3 %), 35 (15.6 %), and 15 (6.7 %) were classified as I, II, III, and IV, respectively. An anteriorly inserted anterior horn was not more frequent in advanced varus OA knees than in previously reported nearly normal or non-arthritic knees. The insertion surface areas were 57.5 ± 18.9, 56.1 ± 16.0, and 56.4 ± 14.4 mm² for types I, II, and III, respectively; these areas did not differ significantly.

Conclusion

Since the incidence of an anteriorly inserted medial meniscus anterior horn was not higher in advanced varus OA knees than in normal or non-arthritic knees, an anteriorly inserted anterior horn may have little or no effect on the aetiology of varus OA knees. This study provides some information for clarifying the aetiology of knee OA.

Level of evidence

IV.

     

The extensor mechanism of the knee joint: an anatomical study

This study investigated the anatomy of the structures that form the extensor mechanism of the knee joint using microsurgical techniques. Ten fresh-frozen human adult cadaveric knees were used. The quadriceps components, the infrapatellar tendon, the patellofemoral ligaments, and their relations to the neighboring anatomical structures were measured. The angles of the vastus lateralis and the vastus medialis muscle fibers to the rectus tendon were 26.6 and 41.1°, respectively. The medial patellofemoral ligament connecting the femoral medial epicondyle to the medial edge of the patella was approximately 54.2 mm long, and its width ranged from 9 to 30 mm. The medial patellomeniscal ligament had a wide attachment to the meniscus whereas the attachment to the patella was narrow. The patellar tendon was 31.9 mm broad at its attachment to the apex of the patella and 27.4 mm wide at its attachment to the tibial tubercle. It was 38–49 mm long. Using the surgical microscope we were able to dissect and identify a trilaminar arrangement of prepatellar fibrous soft tissues. Also, we were able to identify the vessels and nerves around the patella. Details of clinical relevance and the possible pathological implications of the material presented are discussed. Emphasis is placed on the stability of the patellofemoral joint and the complex interaction between a range of factors providing it.     

Repair of a torn medial meniscus with an anteromedial meniscofemoral ligament in an anterior cruciate ligament-injured knee

We report a rare case of longitudinal tear of the anterior segment of the medial meniscus in association with the anteromedial meniscofemoral ligament (AMMFL) in an anterior cruciate ligament-injured knee. The tear was repaired, and the anterior horn was transferred to the tibia using the pull-out technique after excising the AMMFL. Repeat arthroscopy performed 7 months postoperatively revealed that the medial meniscus had completely healed and the anterior horn was firmly fixed to the tibia. Two years after the surgery, the patient could play basketball without any symptom. A posteroanterior flexion weight-bearing radiograph did not show any narrowing of the medial joint space. Considering the excellent healing observed in this case, preservation of the meniscus should be considered despite an association between a torn meniscus and an anomalous insertion.