Perilunate dislocations and transscaphoid perilunate fracture-dislocations: a retrospective study with minimum ten-year follow-up.

PURPOSE: Perilunate dislocations and transscaphoid perilunate fracture dislocations are associated with a high incidence of posttraumatic arthritis. According to the current literature, at medium-term follow-up, radiological signs of arthritis do not correlate with functional scores. The aim of this study was to evaluate patient hand function and the development of posttraumatic arthritis after perilunate dislocations (11 cases) and transscaphoid perilunate fracture dislocations (7 cases) at a minimum 10 years of follow-up. METHODS: A retrospective review was performed including 18 patients with a minimum 10-year (average, 13 y) follow-up. The clinical results were evaluated using the Mayo wrist score and the patient-rated wrist evaluation. Radiological abnormalities were stratified using the Herzberg classification. RESULTS: According to the Mayo wrist score, the authors found 5 excellent, 3 good, 7 fair, and 3 poor results. The mean Mayo wrist score was 76 (range, 60-90). There were 6 type A, 5 type A1, 6 type B1, and 1 type C, according to the Herzberg classification. Posttraumatic degenerative changes were observed in 12 cases. CONCLUSIONS: The presence of radiological arthritis and static carpal instability did not cause reduced function at our minimum follow-up of 10 years. Based on our findings and previously reported series, we conclude that signs of posttraumatic arthritis after perilunate dislocations and transscaphoid perilunate fracture dislocations increase progressively but are well tolerated at an average follow-up of 13 years. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Middle and ring fingers are more exposed to pulley rupture than index and little during sport-climbing: a biomechanical explanation.

BACKGROUND: Finger pulley injury is a common incident observed during sport-climbing. The total rupture of one or several pulleys is highly debilitating and requires surgical reconstruction and/or rehabilitation programs. Literature reports show that fingers are not equally exposed to this injury. The ring and middle fingers are usually injured while the index and little fingers are less exposed. The objective of this study was to determine the biomechanical factors leading to the enhanced exposure of ring and middle finger pulleys. METHOD: Eight subjects were required to exert maximal four-finger force in a specific sport-climbing finger posture. External fingertip forces and finger joint postures were used as input data of a specifically developed biomechanical model of the four fingers (i.e., index, middle, ring and little). This model was based on classical Newton static laws and used an optimization process to quantify the flexor tendon tensions and the pulley forces in each finger. Passive participation of ligaments was also considered into mechanical equations. FINDINGS: Results showed that two main factors could explain the enhanced exposure of ring and middle fingers. Firstly, the fingertip force intensities applied by these two fingers were higher than those observed for the index and little fingers. Secondly, results show that the pulley forces of the ring and middle fingers were close to their rupture thresholds, while it was not the case for the two other fingers. This could be explained by a specific localisation of the finger pulleys of the ring and middle fingers leading to enhanced pulley forces. INTERPRETATION: These results are relevant and could help clinicians to understand finger pulley pathologies and adapt the surgical interventions to reconstruct the fingers pulleys.

Using EMG data to constrain optimization procedure improves finger tendon tension estimations during static fingertip force production.

Determining tendon tensions of the finger muscles is crucial for the understanding and the rehabilitation of hand pathologies. Since no direct measurement is possible for a large number of finger muscle tendons, biomechanical modelling presents an alternative solution to indirectly evaluate these forces. However, the main problem is that the number of muscles spanning a joint exceeds the number of degrees of freedom of the joint resulting in mathematical under-determinate problems. In the current study, a method using both numerical optimization and the intra-muscular electromyography (EMG) data was developed to estimate the middle finger tendon tensions during static fingertip force production. The method used a numerical optimization procedure with the muscle stress squared criterion to determine a solution while the EMG data of three extrinsic hand muscles serve to enforce additional inequality constraints. The results were compared with those obtained with a classical numerical optimization and a method based on EMG only. The proposed method provides satisfactory results since the tendon tension estimations respected the mechanical equilibrium of the musculoskeletal system and were concordant with the EMG distribution pattern of the subjects. These results were not observed neither with the classical numerical optimization nor with the EMG-based method. This study demonstrates that including the EMG data of the three extrinsic muscles of the middle finger as inequality constraints in an optimization process can yield relevant tendon tensions with regard to individual muscle activation patterns, particularly concerning the antagonist muscles.

Sentinel lymph node biopsy in cutaneous melanoma: outcome after 5-years follow-up.

Sentinel lymph node procedure for cutaneous melanoma is largely used and sentinel lymph node status is an important prognostic factor. Few French centers have reported their experience and data. We analysed technique feasibility, recurrence-free and overall-survival rates at 36 and 60 months for the first 62 patients submitted to this technique. The positivity of sentinel lymph nodes was 17.7%. Recurrence-free survival at 36 and 60 months was of 85% and 78% respectively for patients with negative sentinel lymph nodes, whereas the rates were of 45% and 36% respectively for patients with positive sentinel lymph nodes (p = 0.0046). The overall survival rate was of 94% at 36 months and 85% at 60 months for negative patients as opposed to 82% at 36 months and 47% at 60 months for positive patients (p = 0.0019). In our experience, sentinel lymph node technique is a safe procedure with few complications and good pronostic value. This technique allows the identification of patients with a high risk of recurrence who could benefit from early adjuvant therapeutic management. However, these results show that the survival rate of patients with positive sentinel lymph nodes remains significantly lower, even when elective lymph node dissection is performed.

Estimation of finger muscle tendon tensions and pulley forces during specific sport-climbing grip techniques.

The present work displayed the first quantitative data of forces acting on tendons and pulleys during specific sport-climbing grip techniques. A three-dimensional static biomechanical model was used to estimate finger muscle tendon and pulley forces during the "slope" and the "crimp" grip. In the slope grip the finger joints are flexed, and in the crimp grip the distal interphalangeal (DIP) joint is hyperextended while the other joints are flexed. The tendons of the flexor digitorum profundus and superficialis (FDP and FDS), the extensor digitorum communis (EDC), the ulnar and radial interosseus (UI and RI), the lumbrical muscle (LU) and two annular pulleys (A2 and A4) were considered in the model. For the crimp grip in equilibrium conditions, a passive moment for the DIP joint was taken into account in the biomechanical model. This moment was quantified by relating the FDP intramuscular electromyogram (EMG) to the DIP joint external moment. Its intensity was estimated at a quarter of the external moment. The involvement of this parameter in the moment equilibrium equation for the DIP joint is thus essential. The FDP-to-FDS tendon-force ratio was 1.75:1 in the crimp grip and 0.88:1 in the slope grip. This result showed that the FDP was the prime finger flexor in the crimp grip, whereas the tendon tensions were equally distributed between the FDP and FDS tendons in the slope grip. The forces acting on the pulleys were 36 times lower for A2 in the slope grip than in the crimp grip, while the forces acting on A4 were 4 times lower. This current work provides both an experimental procedure and a biomechanical model that allows estimation of tendon tensions and pulley forces crucial for the knowledge about finger injuries in sport climbing.

Pulley rupture and reconstruction in rock climbers.

Hand-grip techniques in modern rock climbing generate climbing-related injuries, especially at the flexor tendon sheath level. The most frequent injury is A2 pulley rupture. The clinical diagnosis is based on bowstringing of the flexor tendon and confirmed by computed tomograph scan or magnetic resonance imaging. The surgical procedure is based on an extensor retinaculum graft to reconstruct the ruptured pulley. It is the only efficient treatment regardless of the time between accident and surgery. Thanks to this surgical procedure, patients recover or improve their former climbing performance. Some precautions before climbing may prevent this injury, and these are listed.

Force sharing and neutral line during finger extension tasks.

There is general consensus that the minimization of the secondary torque of the hand provides a universal model for explaining the force sharing patterns among the fingers. Since biomechanical secondary axes of the hand are unchanged in extension, it appears relevant to validate this model for finger extension forces. Fifteen subjects performed flexion and extension forces in a four-finger task. Each fingertip force was expressed in percentage of the force produced by an individual finger force over the resultant four-finger force (force sharing), and the point of force application of the resultant force was calculated (neutral line). The force-sharing pattern was different for flexion and extension. The index and ring fingers were equally involved, regardless of the task. The neutral line was located differently in flexion and extension, and for proximal and distal force application in extension. The mode of control of the finger redundancy was specific to the force production in flexion and extension. In flexion, the principle of minimization of secondary torque was confirmed. This was not observed in extension. We concluded that the minimization of the secondary torque is not a universal mode of control of the finger redundancy.