Tibial tubercle torsion, a new factor of patellar instability.

INTRODUCTION: External torsion of the anterior tibial tubercle (TT), defined as external rotation around a craniocaudal axis with respect to the posterior femoral condylar plane, may induce patellar instability. To our knowledge no studies have focused on this parameter. The present study aimed to perform an MRI analysis of TT torsion. The study hypothesis was that TT torsion correlates with patellar instability and with 3 of its components: tibial tubercle-trochlear groove (TT-TG) distance, axial engagement index of the patella (AEI), and patellar tilt. MATERIAL AND METHODS: Four observers performed MRI measurements for 2 groups: 37 patellar instability patients (PI group) with history of at least 2 patellar dislocations, and 50 control patients with meniscal lesion but free from patellofemoral pathology. All measurements were taken from 2 axial slices with the posterior condylar plane as reference. RESULTS: The intra-class correlation coefficient (ICC) was 0.88. TT torsion correlated with patellar instability, with a mean 5.8̊ in controls and 17.9̊ in the PI group (P<0.001). There were also excellent correlations between TT torsion and TT-TG distance, patellar tilt and patellar lateralization (measured by AEI), with correlation coefficients greater than 0.85. DISCUSSION: TT torsion is a reproducible measurement, with excellent ICC. It is significantly correlated with patellar instability, with a discrimination threshold of 11.5̊, and correlations with all 3 components of instability. These statistical correlations enable TT torsion to be added to the list of patellar instability factors. Further studies should determine its biomechanical role and assess the contribution of associating TT derotation to medialization or distalization procedures. LEVEL OF EVIDENCE: III; case-control study.

The introduction of a new MRI index to evaluate sagittal patellofemoral engagement.

INTRODUCTION: Patella alta is one of the primary factors of patellofemoral instability and its importance lies in the reduced engagement between patella and trochlea during the early degrees of flexion. The evaluation of patellar height is based on conventional x-rays, CT scan and, more recently, MRI. The objective of this multicentric prospective study is to describe a novel index to assess in the sagittal plane the functional engagement between patella and trochlea. MATERIALS AND METHODS: One hundred and thirty-five patients with objective patellar dislocation were prospectively enrolled between April 2010 and September 2011 and were compared with a second group of 45 controls. All patients underwent a standard MRI and a complete radiographic study. Sagittal engagement was measured as the ratio between the articular cartilage of the patella and the trochlear cartilage length measured on two different MRI slices. RESULTS: The mean Sagittal Patellofemoral Engagement (SPE) index was 0.43 ± 0.18 and ranged from 0.02 to 0.913 in the Objective Patellar Dislocation group versus 0.42 ± 0.11 range 0.22 to 0.55 in controls. In the Patellar Dislocation group the mean Caton-Deschamps index was 1.18 ± 0.21 (range 0.71 to 1.91). There were 58 patients with patella alta, in whom the mean SPE was 0.39 ± 0.18 (range 0.02 to 0.87). Sagittal engagement was significantly higher when compared with patients in the Patellar Dislocation group who had no patella alta (mean 0.46 ± 0.16, range 0.1-0.913). DISCUSSION: The present study introduces a new method to measure the SPE with the use of MRI. The evaluation of the functional engagement of the patella with the femoral trochlea in the sagittal plane can serve as a supplementary tool to the existing methods of evaluating patellar height, and may help to better identify the cases where inadequate engagement is recorded despite the absence of patella alta, so that the need for tibial tuberosity osteotomy may be re-assessed.

Axial MRI index of patellar engagement: a new method to assess patellar instability.

INTRODUCTION: The aim of this study was to define a new index to measure lateral patellar displacement (LPD) using nuclear magnetic resonance imaging (MRI), an axial index of engagement of the patella (AEI) obtained from two different axial MRI views then to validate its use in a prospective series of patients presenting an objective patellar instability (OPI). MATERIALS AND METHODS: One hundred and thirty-five patients with OPI and no history of surgery of the patella were included in a prospective study organized by the French Society of Arthroscopy performed between June 2010 and August 2012. All patients underwent axial and sagittal MRI. The AEI was obtained by projecting predefined patellar and trochlear landmarks (cartilaginous landmarks) on 2 different axial MRI views (one trochlear and one patellar). The results were compared with a series of controls (n=45). RESULTS: The preoperative AEI of the patella was 0.94 ± 0.09 for the control group and 0.84 ± 0.16 for OPI group (P=0.000016). The AEI could be obtained in 100% of the cases if it was measured on 2 MRI views while it could not be measured in 38.5% of the cases if the measurement was only obtained from one MRI view or whenever the widest part of the patella was not across from the femoral trochlea. The AEI did not significantly depend on dysplasia or the presence of a supratrochlear spur. The lowest AIE values were associated with trochlear dysplasia with a supratrochlear spur (P=0.0023) and a more prominent trochlea (P=0.0016). The AEI was correlated with patellar tilt (P<0.000001) and TT-TG on MRI (P<0.000001). DISCUSSION: AEI is a new index to measure LPD. It can be obtained in all cases because it is obtained from two different MRI views. The normal value is close to 1. It can be used to measure patellar instability on the axial plane in patients with OPI, especially in the most severe cases.

[Magnetic resonance imaging of medial meniscus tears with displaced fragment in the meniscal recesses]. / Diagnostic IRM des lambeaux méniscaux médiaux déplacés le long du ligament tibial collatéral.

PURPOSE OF THE STUDY: Displaced meniscus tears generally result from bucket handle tears with subsequent migration of the meniscal fragment into the intercondylar notch. More rarely, the fragment may move into the meniscal recesses. In this situation, the displaced fragment may be difficult to individualize arthroscopically, so preoperative imaging is crucial. Several studies have demonstrated the reliability of magnetic resonance imaging (MRI) for the diagnosis of meniscus injury with fragment displacement in the intercondylar notch. There have been few studies devoted to fragment displacement into the collateral capsuloligamentary structures. The purpose of this study was to describe MRI findings of medial meniscus tears with displaced fragment in the meniscal recesses. MATERIAL AND METHODS: This prospective study was conducted over a 22-month period (May 2003 - February 2005). During this period, we selected 39 patients whose knee MRI displayed a meniscal fragment within the medial collateral recesses. These 39 patients accounted for 15% of knees with MRI-diagnosed meniscal tears (n=272) and 2% of the knee MRI examinations performed during the study period (n=2239). One the MRI series, we studied fragment migration and morphological anomalies of the injured meniscus. For 16 knees, MRI findings could be compared with arthroscopy findings. RESULTS: For 25 knees (65%), the meniscal fragment had migrated downward along the medial tibial plateau and generally (64%) medially to the collateral tibial ligament. For 14 knees (35%) the meniscal fragment had migrated upward, along the medial femoral condyle in 93%, anteriorly to the medial collateral tibial ligament. For 95%, the MRI demonstrated rupture along the free border of the posterior segment and/or the mid segment of the medial meniscus or a decreased height of the posterior segment of the medial meniscus. For 14 of 16 cases, arthroscopy confirmed the meniscal tear and the localization of the displaced fragment. For two knees, arthroscopy confirmed the presence of the meniscal tear but could not identify the displaced meniscal fragment. DISCUSSION: Meniscal tears with fragment displacement into the meniscal recesses has been associated with displacement of a horizontal fissuration which flap tears described arthroscopically by DJ Dandy. Other authors consider these tear flaps as oblique fissurations. In our study, it was sometimes difficult to determine the exact site and orientation of the initial meniscal tear so it is quite likely that meniscal tears with a displaced fragment in the meniscal recesses could correspond to complex predominantly horizontal or oblique meniscal fissurations. The common feature is the presence of an unstable meniscal flap susceptible to migrate. Our findings are in agreement with the literature. Regarding the two cases where the MRI findings could not be confirmed arthroscopically, the MRI visualized a characteristic image of a meniscal fragment displaced downwardly, lying between the medial tibial plateau and the collateral tibial ligament. Arthroscopy visualized the meniscal tear but failed to visualize the displaced fragment. This might be because mobile meniscal fragments return into the joint interspace when the meniscus is manipulated arthroscopically. Small meniscal fragments might also be inaccessible arthroscopically.

[Medial patellofemoral ligament reconstruction with gracilis autograft for patellar instability]. / Plastie du ligament fémoro-patellaire médial avec le tendon du gracile pour stabilisation de la patella.

We describe a technique for patellar stabilization by reconstruction of the medial patellofemoral ligament with the gracilis tendon. The tendon is anchored posteriorly on the soft tissue of the medial femoral epicondyle and anteriorly on the medial border of the patella. The plasty is completed by suture of the medial patellar wing. Inferior or medial transposition of the tibial tubercle may be associated. We have used this technique since 1995 for 145 knees with patellar instability. The small incisions have the advantages of minimally invasive surgery, particularly for the postoperative period and the cosmetic effect.

["Isolated" injury of the posterior cruciate ligament. Surgical treatment of isolated posterior cruciate ligament tears: a multicentric retrospective study of 103 patients]. / Traitement chirurgical d'une rupture isolée du ligament croisé postérieur: résultats d'une série rétrospective multicentrique de 103 patients.

PURPOSE OF THE STUDY: We present a retrospective multicentric series of carefully selected patients presenting "isolated" laxity of the posterior cruciate ligament. MATERIAL AND METHODS: The series included 103 patients who were reviewed clinically (with a dedicated review chart) and radiographically with measurement of posterior laxity (Telos 15 kg). RESULTS: In these patients with an isolated injury of the PCL (without associated injury of the peripheral ligament) DISCUSSION: The short follow-up of this series (four years) does not enable an assessment of the risk or benefit of PCL ligamentoplasty for arthrosic knees.

[Arthrotic sciatica caused by radicular compression of osteophytic origin in the lateral recess. Apropos of 18 cases]. / Sciatiques "arthrosiques" par compression radiculaire d'origine ostéophytique dans le récessus latéral. A propos de 18 observations

The authors report 18 cases of arthrosic sciatica due to toot compression in the lateral recess by posterior corporeal and/or posterior apophyseal osteophytosis. The authors study the clinical and radiological characteristics that may indicate the diagnosis and discuss the different mechanisms by which vertebral arthrosis can lead to radicular compression. When surgery is necessary because of the persistent nature of the sciatica, a broader approach should be undertaken than that required for excision of the disc, in order to explore fully the roots, the multiplicity of possible compression sites being one of the essential characteristics of these cases of arthrosic radiculopathy. Study of the literature and of the series of sciatica patients operated upon by the authors shows that although discal hernia is far from being the most frequent cause of common sciatica, arthrosic compression is a cause that cannot be ignored, especially in aged subjects.

Degenerative spondylolisthesis.

Degenerative spondylolisthesis is one important type of spinal stenosis. The spinal canal stenosis varies in degree. This is the result of anterior slipping of the whole vertebra, usually L4 on L5. The clinical picture is not greatly different from that observed in the other types of lumbar canal stenosis. The surgical management involves decompression of the cauda equina by laminectomy. Often this is associated with arthrectomy to decompress the nerve roots. Extensive excision of the neural arch may result in further spinal instability for which spinal fusion is generally advisable.

[Degenerative spondylolisthesis. Clinical manifestations and treatment apropos of 26 operated cases]. / Spondylolisthésis dégénératif. Manifestations cliniques et traitement à propos de 26 cas opérés

The authors report 26 cases of surgically treated degenerative spondylolisthesis. Twelve patients complained of permanent uni or bilateral sciatica. All the others had a syndrome of intermittent claudication with pain and paresthaesia. The authors stress once again the highly evocative nature of this syndrome which reflects involvement of the nerve roots in the stenosed lumbar canal. Treatment consisted of lamino-arthrectomy which resulted in the disappearance of symptoms in most of cases. In four cases, vertebral slipping worsened during the post-operative cowise with, in three cases a recurrence of symptoms necessitating a complementary arthrodesis. This risk of increased slipping is a result of the instability created by the arthrectomy, especially when it is bilateral, and has led the authors to widen their indications for routine complementary postero-lateral arthrodesis.