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Background: In more than 50% of cases, anterior cruciate ligament (ACL) lesions lead to post-traumatic osteoarthritis. Ligament reconstruction stabilizes the joint, but the tear seems to impair the poroelasticity of the cartilage: synovial membrane fluid inflammation is observed 3 weeks after tearing. There have been some descriptions of visible cartilage changes, but poroelasticity has never been analyzed at this early stage. The present animal study aimed to determine 1) whether cartilage showed early poroelastic deterioration after ACL tear; 2) whether impairment correlated with macroscopic changes; and 3) whether cartilage poroelasticity deteriorated over time. Hypothesis: In the days following trauma, cartilage poroelasticity is greatly impaired, without macroscopically visible change. Material and methods: ACL tear was surgically induced in 18 New-Zealand rabbits. Cartilage poroelasticity was assessed on indentation-relaxation test in 3 groups: “early”, at 2 weeks postoperatively (n=6), “mid-early” at 6 weeks (n=6) and in a non-operated control group (“non-op”). Macroscopic changes were scored in the same groups. Results: Poroelastic impairment was greatest at the early time-point (2 weeks). Permeability ranged from a mean 0.08±0.05x10-15 m4/Ns (range, 0.028-0.17) in the “non-op” group to 1.03±0.60x10-15 m4/Ns (range, 0.24-2.15) in the “early” group (p=0.007). Shear modulus ranged from 0.53±0.11 MPa (range, 0.36-0.66) to 0.23±0.10 MPa (range, 0.12-0.43), respectively (p=0.013). Macroscopic deterioration, on the other hand, differed significantly only between the “mid-early” and the “non-op” groups: p=0.011 for cartilage deterioration and p=0.008 for osteophyte formation. At the “mid-early” time point, poroelastic deterioration was less marked, with 0.33±0.33x10-15 m4/Ns permeability (range, 0.06-1.06) and shear modulus 0.30±0.10 MPa (range, 0.13-0.41: respectively p=0.039 and p=0.023 compared to the “non-op” group. Discussion: The severe rapid deterioration in poroelasticity following ACL tear in an animal model, as notably seen in increased permeability, corresponds to changes in cartilage microstructure, with easier outflow of interstitial fluid. This mechanical degradation may underlie onset of microcracks within the cartilage, leading to physiological loading that the cartilage by its nature is unable to repair. Further investigations are needed to correlate these experimental data with clinical findings. Level of evidence: III; comparative study with control group.

Tendon lengthening and transfer are usually indicated for certain neuromuscular disorders, peripheral or central nerve injury, congenital disorder or direct traumatic or degenerative musculotendinous lesion. In musculotendinous lengthening, technique depends on muscle anatomy, degree of correction required, and the need to avoid excessive loss of force. Lengthening within the muscle or aponeurosis is stable. In the tendon, however, it may provide greater gain but is not stable and requires postoperative immobilization to avoid excessive lengthening. Tendon transfer consists in displacing a muscle's tendon insertion in order to restore function. The muscle to be transferred is chosen according to strength, architecture and course, contraction timing, intended direction, synergy and the joint moment arm to be restored. Functions to be restored have to be prioritized, and alternatives to transfer should be identified. The principles of tendon transfer require preoperative assessment of the quality of the tissue through which the transfer is to pass and of the suppleness of the joints concerned. During the procedure, transfer tension should be optimized and the neurovascular bundle should be protected. The method of fixation, whether tendon-to-bone or tendon-to-tendon suture, should be planned according to local conditions and the surgeon's experience.

Summary Purpose Assessing functional outcome from patient-based outcomes questionnaires are essential to the evaluation of adolescent idiopathic scoliosis surgical treatment Methods At the minimum follow-up of 2 years, 45 operated on adolescent idiopathic scoliosis patients were mailed the French version of the Scoliosis Research Society Outcome Instrument (SRS-22) questionnaires containing items on pain, activities of daily living, and satisfaction. Results Mean values of the SRS-22 domains were 3,66 for the Pain domain, 3,85 for the Self-perceived image domain, 4,32 for the Function domain, 3,52 for the Mental health domain and 4,12 for the Global satisfaction with management domain. Mean value of the global SRS-22 score was 3,88. We showed no differences in functional SRS-22 health status in patients according to the type of curve (Lenke classification). We showed statistically significant correlations between the gain of Cobb angle and Patients self-image and function domain scores. There was a statistically significant correlation between preoperative Cobb angle and patient satisfaction with management. Conclusions Even if Function and Self-image scores in our patients are close to control group values, indicating good short to mid-term outcome of surgical treatment, scores for pain and mental health status were significantly lower in patients than controls. Long-term follow-up studies conducted by multiple surgeons over successive generations are mandatory to assess clinical significance of these differences. Level of evidence Level IV. Retrospective study