An increased LTPS is associated with an increased risk for early ACL graft failure, regardless of graft type. Orthopaedic surgeons should consider measuring the LTPS as part of the preoperative assessment of ACL-injured patients.

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The subsynovial connective tissue (SSCT) in the carpal tunnel may participate in the origin of carpal tunnel syndrome (CTS), yet material properties of the SSCT have not been well-characterized. We investigated the response of the SSCT to repeated ramp stretch tests. Eight human cadaver wrists were used. The physiological excursion of the flexor digitorum superficialis of the third digit (FDS 3) was measured, starting from a neutral position to maximal flexion of the metacarpophalangeal and proximal interphalangeal joints. The FDS 3 tendon was pulled to 40, 60, 90, and 120% of the physiological excursion. Two ‘ramp stretch’ cycles were performed at every excursion level, except for 120% of excursion, where 3 cycles were performed. The ratio of energy absorbed between the second (E2) and first (E1) ramp-stretch was 0.94 (Std. Dev. = 0.07) for 60%, 0.84 (Std. Dev. = 0.11) for 90%, and 0.68 (Std. Dev. = 0.11) for 120% of the physiological excursion. A significant decrease occurred in energy absorbed after the first ramp-stretch cycle at 90% and 120% of the physiological excursion, which was not seen at 60%. Our data are consistent with a stepwise damage occurring in the SSCT. Furthermore, the damage seems to initiate within the physiological range of tendon excursion. This finding may be important in understanding the pathophysiology of conditions that are associated with SSCT pathology, such as carpal tunnel syndrome.

Longevity of total anatomic and reversed shoulder arthroplasty largely depends on accurate correction of glenoid deformity and correct positioning and fixation of the glenoid component. However, the morphology of the scapula is inconsistent, varying degrees of osteoarthritis cause numerous anatomic changes, and standard 2-dimensional imaging and standard surgical instrumentation are imprecise for preoperative planning and execution of glenoid reconstruction. Recently, various authors have shown that preoperative 3-dimensional surgical planning and computer navigation technology may increase the accuracy and repeatability of the implantation of the glenoid component, especially for the position and orientation of the glenosphere and screws in reversed arthroplasty. These novel techniques may allow the surgeon to better define the preoperative deformity, select the optimal implant position, and then accurately execute the plan at the time of surgery. Future studies are needed to determine the long-term effect on functional outcome and cost-effectiveness of computer-assisted technology in shoulder arthroplasty.

SUMMARY Fibrosis of the subsynovial connective tissue (SSCT) in the carpal tunnel is the most common histological finding in carpal tunnel syndrome (CTS). Fibrosis may result from damaged SSCT. Previous studies found that with low-velocity (2 mm/s), tendon excursions can irreversibly damage the SSCT. We investigated the effect of tendon excursion velocity in the generation of SSCT damage. Nine human cadaver wrists were used. Three repeated cycles of ramp-stretch testing were performed simulating 40, 60, 90 and 120% of the middle finger flexor tendon superficialis physiological excursion with an excursion velocity of 60 mm/s. Energy and force were calculated and normalized by values obtained in the first cycle for each excursion level. Data were compared with low-velocity excursion data. For high-velocity excursions, a significant drop in the excursion energy ratio was first observed at an excursion level of 60% physiological excursion (P<0.024) and that for low-velocity excursions was first observed at 90% physiological excursion (P<0.038). Furthermore, the energy ratio was lower at 60% for high velocities (P≤0.039). Increasing velocity lowers the SSCT damage threshold. This finding may be relevant for understanding the pathogenesis of SSCT fibrosis, such as that accompanying CTS, and a relationship with occupational factors.