Association of internal rotation of the knee joint with recurrent subluxation of the lateral meniscus

Anterior Mobility of the Posterior Horn of the Lateral Meniscus Is Associated With Abnormal Magnetic Resonance Imaging Findings of Anteroinferior Popliteomeniscal Fascicle and Posterosuperior Popliteomeniscal Fascicle as Well as a Clinical History of Catching or Locking Symptoms

Purpose

To identify predictors of anterior mobility of the posterior horn of the lateral meniscus (PHLM) among patient demographics (age, sex), clinical characteristics (a history of catching or locking symptoms [CLS], body mass index, alignment of limb), and magnetic resonance imaging (MRI) findings of 4 restraints: anteroinferior popliteomeniscal fascicle (aiPMF), posterosuperior popliteomeniscal fascicle (psPMF), posteroinferior popliteomeniscal fascicle (piPMF), and meniscofibular ligament (MFibL).

Methods

Between October 2010 and December 2014, patients who underwent arthroscopic measurement of mobility of the PHLM were identified. The Sakai classification was used to classify aiPMF and psPMF on MRI into the following 3 types: type A, the fascicle was depicted with obvious continuity and with a low-intensity band; type B, depicted with continuity but with an ambiguous intensity structure; and type C, depicted with discontinuity or not visible. Magnetic resonance images of the piPMF and MFibL were evaluated as presence or absence. The mobility of the PHLM was measured arthroscopically at traction forces of 10 and 20 N.

Results

A total of 73 patients (47 men, mean age 41.8 ± 19.3 years) were included. Multivariate regression analyses revealed aiPMF type C and psPMF types B and C to be independent factors associated with mobility at both traction forces, and CLS was an independent factor at a traction force of 20 N. Compared with that of type A, the increased mobility of aiPMF type C was 5.0 mm (P = .019) and 5.6 mm (P = .011) at 10 and 20 N, respectively; the increased mobility of psPMF type B was 2.5 mm (P = .007) and 3.5 mm (P = .0003), respectively; and the increased mobility of psPMF type C was 3.3 mm (P = .021) and 3.6 mm (P = .014), respectively. The increased mobility associated with CLS was 3.5 mm at 20 N (P = .022).

Conclusions

Anterior displacement of the PHLM induced by an external traction force at 90° of flexion of the knee joint was associated with abnormal MRI findings of the anteroinferior popliteomeniscal fascicle and posterosuperior popliteomeniscal fascicle, as well as a history of catching or locking symptoms.

Clinical Relevance

Understanding signs and symptoms and associated pathology in patients with symptomatic anterior mobility of the posterior horn of the lateral meniscus may help guide best treatment.

Injury pattern simulation and mapping of complex tibial plateau fractures that involve the posterior plateau with three-dimensional computed tomography

Background

Tibial plateau fractures involving the posterior plateau (TPFIPs) are complex intra-articular fractures that are difficult to stabilize. Understanding the characteristics of these fractures together with the injury pattern is beneficial for surgeons to choose an optimal treatment strategy. However, the complicated morphology and injury patterns of TPFIPs are poorly characterized. The purpose of this retrospective study was to investigate the injury patterns and fracture characteristics of complex TPFs by applying three-dimensional (3D) simulation and fracture mapping methods.

Methods

In total, 171 TPFIPs were retrospectively reviewed, and the injury pattern was simulated and analyzed by applying a 3D method with Mimics software, which allowed matching of the fractured articular surfaces of the tibial plateau to the femoral condyle surface. The major articular fracture lines were mapped and then superimposed on a template. The tibial motion angle after fracture injury pattern simulation and the major fracture line angle were quantitatively analyzed, while the injury patterns and fracture characteristics were qualitatively analyzed.

Results

Four main injury patterns with distinctive fracture characteristics were observed in this study. In total, 72 TPFs exhibited extension as the pattern of injury with a split posterolateral fragment, and 61 fractures exhibited the flexion-internal rotation injury pattern; compression was the main feature of posterolateral fractures. Furthermore, 21 fractures exhibited the flexion-external rotation injury pattern, with a small posteromedial fragment, and 17 fractures exhibited the flexion-neutral injury pattern, with both parts of the posterior plateau fracture and anterior dislocation being observable. The major articular fracture line angles were significantly different between the four main injury patterns (85.92°, 46.79°, 148.26°, and 16.21°, median values, P<0.05). Two injury patterns, namely, flexion-internal rotation and flexion-external rotation, exhibited rotation in the axial plane (24.13°±8.33°, −15.13°±5.14°, P<0.05).

Conclusions

In this study, a method involving a simulated injury pattern was developed and combined with evaluations of fracture characteristics, including two-dimensional (2D) and 3D analyses, to comprehensively describe both the morphologies and injury patterns of TPFIPs.

Arthroscopic meniscus repair for recurrent subluxation of the lateral meniscus

PURPOSE

This study was undertaken to diagnose and to document the clinical results and technical aspects of arthroscopic meniscus repair for recurrent subluxation with peripheral tears around the popliteal hiatus of the lateral meniscus.

METHODS

Twenty-three patients (24 knees) with symptomatic recurrent subluxation of the lateral meniscus treated by arthroscopic meniscus repair were included. The inclusion criteria were: (1) patients with knee pain, locking or snapping symptoms despite 3 months of conservative treatment; (2) non-discoid lateral meniscus; (3) stable knee, and (4) tears involving the red-white or red-red zone. All tears were repaired by either the modified all-inside suture technique only or a combination of the modified all-inside and modified outside-in suture techniques. Clinical results were evaluated preoperatively and at final follow-up according to Tegner activity level, Lysholm knee, and Hospital for Special Surgery (HSS) scores.

RESULTS

No reoperations were required after a median follow-up of 41 months (range 24-124). Although recurrence of a locking episode was documented in one knee and catching sensations were experienced in three knees, those patients did not require reoperation. At the last follow-up, the median Tegner activity level had improved significantly from 4 (range 2-6) to 7 (range 3-10, p < 0.0001), the median Lysholm knee score improved from 76 (range 25-90) preoperatively to 94 (range 76-100) at final follow-up (p < 0.0001), and the median preoperative HSS score improved from 86 to 95 at final follow-up (p < 0.0001).

CONCLUSION

The described arthroscopic meniscus suture technique is effective for treating symptomatic recurrent subluxation of the lateral meniscus without any complications or recurrence. Clinical suspicion and understanding of recurrent subluxation with lateral meniscus are important to diagnose the disease especially when definite meniscal tear signs are absent on magnetic resonance imaging.

LEVEL OF EVIDENCE

IV.

Reconstruction of the Popliteomeniscal Fascicles for Treatment of Recurrent Subluxation of the Lateral Meniscus

Recurrent subluxation of the lateral meniscus is characterized by episodes of mechanical locking of the knee joint. To completely preclude the posterior segment of the lateral meniscus from undergoing anterior dislocation during deep knee flexion, the structures to which it is attached need to be relatively taut. The posterosuperior popliteomeniscal fascicle retains its tension during deep knee flexion; therefore, reconstruction of the posterosuperior and anteroinferior popliteomeniscal fascicles was performed with an autograft harvested from the iliotibial band. This technique provides stabilization of the posterior segment of the lateral meniscus during deep knee flexion without interfering with the normal movement of the lateral meniscus throughout the range of motion of the knee joint.

A Case of Bilateral Permanent Subluxation of the Lateral Meniscus

We report a case of bilateral, permanent subluxation of the lateral meniscus. To our knowledge, the present case is the first reported description of bilateral irreducible anterior dislocation of the posterior segment of the lateral meniscus. This disorder is characterized by a flipped meniscus sign of the lateral meniscus on sagittal magnetic resonance images of the knee joint, with no history of trauma or locking symptoms. A detailed examination of serial magnetic resonance images of the lateral meniscus can help differentiate this condition from malformation of the lateral meniscus, that is, a double-layered meniscus. We recommend two-stage treatment for this disorder. First, the knee joint is kept in straight position for 3 weeks after the lateral meniscus is reduced to the normal position. Second, if subluxation of the lateral meniscus recurs, meniscocapsular suture is then performed. Although subluxation of the lateral meniscus without locking symptoms is rare, it is important to be familiar with this condition to diagnose and treat it correctly.

The effect of knee flexion and rotation on the tibial tuberosity-trochlear groove distance

PURPOSE

The purpose was to measure the effect of flexion and additional rotation of the femur relative to the tibia on the tuberosity-trochlear groove distance (TT-TG) in the same subject in 20 cadaveric knees joint.

METHODS

In 20 human adult cadavers, formal fixed knees (age: 81.9 years, SD 12.3; 10 female) CT scans were performed in extension and 30° of flexion as well as in neutral, maximal possible internal (IR), and external rotation (ER). On superimposed CT scan images, TT-TG was measured in each position. TT-TG measurements were correlated in all knee positions.

RESULTS

TT-TG in full extension/neutral rotation was 7.8 mm (SD 3.4, range, 2.4-15.3). TT-TG in full extension and IR was significantly lower, and TT-TG in full extension and ER was significantly higher than in neutral rotation (5.4 ± 2.3 vs. 10.9 ± 4.8 mm; P < 0.001). IR and ER varied between 1.0°-7.6° and 0.2°-9.2°, respectively. TT-TG in 30° flexion/neutral rotation was 3.9 mm (SD 1.8, range, 1.3-7.8), which was significantly lower than in full extension and neutral rotation (P < 0.001). TT-TG in 30° flexion and IR was significantly lower, and TT-TG in 30° flexion and ER was significantly higher than values obtained in neutral rotation (2.7 ± 1.2 vs. 6.5 ± 3.4 mm; P < 0.001). IR and ER in 30° flexion varied between 0.6°-10.7° and 1.9°-13.0°, respectively.

CONCLUSION

Flexion as well as rotation of the knee joint significantly alters the TT-TG. These results may have wider clinical relevance in assessing TT-TG and further decisions based on it.

Arthroscopic evaluation of patellofemoral congruence with rotation of the knee joint and electrical stimulation of the quadriceps

PURPOSE

The aim of this study was to investigate the pathoanatomic features of patellar instability by arthroscopically comparing patellofemoral congruence with rotation of the knee joint and/or electrical stimulation of the quadriceps (ESQ) between knees with and without patellar instability.

METHODS

We retrospectively examined 83 knee joints in 83 patients. The joints were classified into 2 groups: group 1 comprised those without a history of patellar dislocation and included 59 patients (25 male and 34 female patients), and group 2 comprised those with a history of patellar dislocation and included 24 patients (9 male and 15 female patients). Evaluation of patellofemoral congruence at 30° of flexion of the knee joint was conducted based on an axial radiograph and arthroscopic findings. The congruence angle was measured on the radiograph. The position of the patellar central ridge (PPCR) on the trochlear groove during arthroscopy was measured using still video frames of knee joints with rotational stress and/or ESQ. Statistical differences in the measurements between the 2 groups were assessed with the unpaired t test and the area under the receiver operating characteristic curve of each measurement.

RESULTS

There were significant differences (P < .0001) between the 2 groups in the congruence angle on radiographs and PPCR in knee joints with rotational stress and/or ESQ on arthroscopy. External and internal rotation of the knee joint caused lateral and medial patellar shift, respectively, in both groups, but the shift was significantly larger in group 2. ESQ in addition to rotation caused further patellar shift in group 2 but reduced patellar shift in group 1. Measurement of PPCR with external rotation of the knee and ESQ was the only method to show an area under the receiver operating characteristic curve of 1.

CONCLUSIONS

There were significant differences in the effects of rotation of the knee joint and/or ESQ on patellofemoral congruence at 30° of flexion of the knee joint on arthroscopy between knees with and without patellar instability.

LEVEL OF EVIDENCE

Level III, diagnostic study of nonconsecutive patients.

Three dimensional, radiosteriometric analysis (RSA) of equine stifle kinematics and articular surface contact: a cadaveric study

REASONS FOR PERFORMING STUDY

Studies examining the effect of stifle joint angle on tibial rotation, adduction-abduction angle and articular contact area are lacking.

OBJECTIVES

To test the hypothesis that tibial rotation, adduction-abduction angle and articular contact area change with stifle joint angle.

STUDY DESIGN

Descriptive study of normal kinematics and articular contact patterns of the equine stifle through the functional range of motion using 3 dimensional (3D) radiosteriometric analysis (RSA) and equine cadaver stifles.

METHODS

Multiple, radiopaque markers were embedded in the distal femur and proximal tibia and sequential, biplanar x-rays captured as the stifle was passively extended from 110° to full extension. Computer-programmed RSA was used to determine changes in abduction-adduction and internal-external rotation angles of the tibia during stifle extension as well as articular contact patterns (total area and areas of high contact) through the range of motion.

RESULTS

The tibia rotated externally (P < 0.001) as the stifle was extended. Tibial abduction occurred from 110-135° of extension (P < 0.001) and tibial adduction occurred from 135° through full extension (P = 0.009). The centre of joint contact moved cranially on both tibial condyles during extension with the lateral moving a greater distance than the medial (P = 0.003). Articular contact area decreased (P = 0.001) in the medial compartment but not in the lateral compartment (P = 0.285) as the stifle was extended. The area of highest joint contact increased on the lateral tibial condyle (P < 0.001) with extension but decreased (P = 0.001) on the medial tibial condyle.

CONCLUSIONS

Significant changes occur in tibial rotation, adduction-abduction angle and articular contact area of the equine stifle through the functional range of motion. Understanding the normal kinematics of the equine stifle and the relationship between joint positions and articular contact areas may provide important insight into the aetiology and location of common stifle joint pathologies (articular cartilage and meniscal lesions).

Magnetic resonance imaging and arthroscopic findings of the popliteomeniscal fascicles with and without recurrent subluxation of the lateral meniscus

PURPOSE

The aim of this study was to examine the posterosuperior popliteomeniscal fascicle (sPMF) and anteroinferior popliteomeniscal fascicle (iPMF) by use of magnetic resonance imaging in control knee joints and joints with recurrent subluxation of the lateral meniscus (RSLM) to determine the incidence of abnormal popliteomeniscal fascicles (PMFs) in these groups.

METHODS

Knee joints were diagnosed with RSLM when there was a history of mechanical locking episodes and when subluxation of the lateral meniscus was recognized on arthroscopy. In this study 238 knee joints were evaluated. The joints were classified into a control group (215 joints), RSLM group (16 joints), and contralateral RSLM group (7 joints). Classification of the sPMF (iPMF) on magnetic resonance imaging was as follows: type I, a tense, low-intensity band ran from the superior (inferior) border of the lateral meniscus to the popliteus tendon; type II, an unclear band ran from the superior (inferior) border of the lateral meniscus; and type III, no band was observed. Types II and III were thought to exhibit abnormal PMFs. The distribution of knee joints among the 3 groups and PMF types was examined.

RESULTS

Percentages of abnormal sPMFs and iPMFs were 40% and 26%, respectively, in the control group; 100% and 29%, respectively, in the contralateral RSLM group; and 100% and 100%, respectively, in the RSLM group. A significant difference in the distribution of knee joints by classification of sPMFs was recognized between the control and contralateral RSLM groups (P < .0001). A significant difference in iPMFs was also recognized between the contralateral RSLM and RSLM groups (P = .0005).

CONCLUSIONS

A significantly high incidence of abnormal sPMFs was found in RSLM and contralateral knees. Thus abnormal sPMFs existed in both knee joints before patients had locking symptoms, suggesting that abnormal sPMFs may be required for locking symptoms. A significantly high incidence of abnormal iPMFs was found only in the knee joints with RSLM. An abnormal iPMF is thus the essential lesion to allow the at-risk lateral meniscus to become unstable beyond the rate of control knees.

LEVEL OF EVIDENCE

Level III, case-control study.