31 years survival rate of ARPE® single-mobility prosthesis in trapeziometacarpal osteoarthritis.

A retrospective study of 41 trapeziometacarpal prostheses showed that the implant survival rate decreased linearly over time with a critical period in the first years; ranging from 83% after 5 years to 50% after 30 years.Level of evidence: IV.

The consequences of a thoracic outlet syndrome's entrapment model on the biomechanics of the ulnar nerve - Cadaveric study.

STUDY DESIGN: A cross sectional cadaveric measurement study. INTRODUCTION: The etiology of entrapment neuropathies, such as carpal tunnel syndromes or thoracic outlet syndromes (TOS), is usually not only linked with the compressive lesion of the nerve but can also be associated with fibrosis and traction neuropathy. PURPOSE OF THE STUDY: This work studies the biomechanics of the ulnar nerve in a cadaveric model of thoracic outlet syndrome (TOS). We explored the biomechanical impact of a restriction of mobility of the ulnar nerve. We measured if it could significantly affect the deformation undergone by the nerve on the rest of its path. METHODS: We studied 14 ulnar nerves from 7 embalmed cadavers. We opened three 6.5cm windows (at the wrist, forearm, and arm), and two optical markers 2cm apart were sutured to the ulnar nerve. We then studied the deformation of the ulnar nerve in three successive tensioning positions inspired by the ULNT3 manoeuvre (Upper Limb Neural Test 3). We then fixed the brachial plexus to the clavicle to mimic a nerve adhesion at the thoracic outlet. RESULTS: Fixing the brachial plexus to the clavicle bone had significant effects on ulnar nerve mobility. In the position of intermediate tension, the nerve deformation increased by +0.68% / +1.43% compared to the control measure. In the position of maximum tension, it increased by +1.16% / +1.94%, pushing the nerve beyond the traumatic threshold of 8% of deformation causing reversible damage to axonal transport and vascularization. CONCLUSIONS: Our nerve adhesion at the thoracic outlet showed significant effects on the mobility of the ulnar nerve compared to the control situation, by significantly increasing the deformation undergone throughout the rest of the nerve's course, and by taking it over the 8% of physiological traumatic deformation.

Sex differences in semitendinosus muscle fiber-type composition.

Sex differences in muscle fiber-type composition have been documented in several muscle groups while the hamstring muscle fiber-type composition has been poorly characterized. This study aimed to compare the semitendinosus muscle composition between men and women. Biopsy samples were obtained from the semitendinosus muscle of twelve men and twelve women during an anterior cruciate ligament reconstruction. SDH and ATPase activities as well as the size and the proportion of muscle fibers expressing myosin heavy chain (MyHC) isoforms were used to compare muscle composition between men and women. The proportion of SDH-positive muscle fibers was significantly lower (37.4 ± 11.2% vs. 49.3 ± 10.6%, p < 0.05), and the percentage of fast muscle fibers (i.e., based on ATPase activity) was significantly higher (65.8 ± 10.1% vs. 54.8 ± 8.3%, p < 0.05) in men versus women. Likewise, men muscles exhibited a lower percentage of the area that was occupied by MyHC-I labeling (35.6 ± 10.1% vs. 48.7 ± 8.9%; p < 0.05) and a higher percentage of the area that was occupied by MyHC-IIA (38.3 ± 6.7% vs. 32.5 ± 6.5%; p < 0.05) and MyHC-IIX labeling (26.1 ± 9.6% vs. 18.8 ± 8.5%; p = 0.06) as compared with women muscles. The cross-sectional area of MyHC-I, MyHC-IIA, and MyHC-IIX muscle fibers was 31%, 43%, and 50% larger in men as compared with women, respectively. We identified sex differences in semitendinosus muscle composition as illustrated by a faster phenotype and larger muscle size in men as compared with women. This sexual dimorphism might have functional consequences.

Arthroscopic Treatment of Translunate Perilunate Injuries, Not Dislocated (PLIND).

Background Translunate perilunate dislocations were recently described as well as perilunate injuries, not dislocated (PLIND). The authors present a case of transradial styloid, translunate PLIND which sustained a full arthroscopic reduction and internal fixation. Case Description A 33-year-old man sustained a transradial styloid, translunate PLIND due to a fall from a truck with his wrist in hyperextension. The diagnosis was made at the acute stage. Full arthroscopic reduction and internal fixation with Kirschner wires was performed, followed by a 6 weeks' immobilization period. Uneventful healing of both the lunate and radial styloid were observed at 6 weeks and confirmed with a computed tomography scan. At 4 years of follow-up, the Lyon wrist score was 78% (good). Literature Review Very few lunate fractures are described in the literature. Translunate perilunate dislocations were recently described as well as PLIND. To the best of the authors' knowledge, a case of transradial styloid, translunate PLIND which sustained a full arthroscopic reduction and internal fixation has never been reported so far. Clinical Relevance This case reports a unique pattern of transradial styloid, translunate PLIND and outlines the usefulness of a full arthroscopic treatment. An open reduction for this pattern of injury would have been extensive, difficult, and probably unreliable.

Axial patellar engagement index and patellar tilt after medial patello-femoral ligament reconstruction in children and adolescents.

BACKGROUND: The medial patello-femoral ligament (MPFL) is a major patellar stabiliser whose reconstruction in adults involves graft fixation within a femoral tunnel. In skeletally immature patients, in contrast, the graft is fixed to the soft tissues to allow normal growth. The primary objective of this prospective study was to perform computed tomography (CT) and magnetic resonance imaging (MRI) assessments of medium-term correction of patellar tilt and of the axial patellar engagement index (AEI) after a paediatric variant of MPFL reconstruction in skeletally immature patients. HYPOTHESIS: MPFL reconstruction, performed alone or combined with other procedures in skeletally immature patients, decreases patellar tilt and improves the AEI. MATERIAL AND METHODS: Eighteen children and adolescents with a median age of 14.6 years (range, 8-17 years) who underwent MPFL reconstruction on 20 knees were included in this prospective observational study. A double-strand gracilis tendon graft passed through the medial collateral ligament was used. MPFL reconstruction was performed alone in 13 knees and was combined with lateral retinaculum release, tibial tuberosity translation, and/or trochleoplasty in 7 knees. Patellar tilt and AEI values determined on preoperative and post-operative imaging studies with the quadriceps relaxed and contracted were compared. A physical examination was also performed. RESULTS: From baseline to last follow-up after a mean of 43 months (range, 24-63 months), patellar tilt decreased from 20° preoperatively to 9° with the quadriceps relaxed and from 33° to 15.4° with the quadriceps contracted. The AEI increased from 0.78 at baseline to 0.93 at last follow-up. No dislocation or subluxation recurrences were recorded during follow-up. DISCUSSION: The patellar tilt and AEI improvements seen after paediatric MPFL reconstruction confirm the study hypothesis. This is the first prospective study of patellar position in the axial plane as assessed by CT and MRI after paediatric MPFL reconstruction. In everyday clinical practice, 3D assessments of patellar tilt and the AEI should be performed to evaluate correction of the abnormalities. LEVEL OF EVIDENCE: II, non-randomised prospective observational study.