The triangular fibrocartilage complex (TFCC) is a known stabiliser of the distal radioulnar joint (DRUJ). An injury to these structures can result in significant disability including pain, weakness and joint stiffness. The contribution each of its components makes to the stability of the TFCC is not well understood. This study was undertaken to investigate the role of the individual ligaments of the TFCC and their contribution to joint stability.

The study was undertaken in two parts. 30 cadaveric forearms were studied in each group. The ligaments of the TFCC were progressively sectioned and the resulting effect on the stability of the DRUJ was measured. A custom jig was created to apply a 20N force through the distal radius, with the ulna fixed.

Experiment one measured the effect on DRUJ translation after TFCC sectioning. Experiment two added the measurement of rotational instability.

Part one of the study showed that complete sectioning of the TFCC caused a mean increase in translation of 6.09(±3) mm. Sectioning the palmar radioulnar ligament of the TFCC caused the most translation.

Part two demonstrated a change in rotation with a mean of 18 (± 6) degrees following sectioning of the TFCC. There was a progressive increase in rotational instability until the palmar radioulnar ligament was also sectioned.

Linear translation consistently increased after sectioning all of the TFCC ligaments, confirming its importance for DRUJ stability. Sectioning of the palmar radioulnar ligament most commonly caused the greatest degree of translation. This suggests injury to this ligament would more likely result in a greater degree of translational instability. The increase in rotation also suggests that this type of instability would be symptomatic in a TFCC injury.

The goal of this study was to identify the effect of mismatches in the subchondral bone surface at the native:graft interface on cartilage tissue deformation in human patellar osteochondral allografts (OCA). Hypothesis: large mismatches in the subchondral bone surface will result in higher stresses in the overlying and surrounding cartilage, potentially increasing the risk of graft failure.

Nano-CT scans of ten 16mm diameter cadaveric patellar OCA transplants were used to develop simplified and 3D finite element (FE) models to quantify the effect of mismatches in the subchondral bone surface. The simplified model consisted of a cylindrical plug with a 16 mm diameter (graft) and a washer with a 16 mm inner diameter and 36 mm outer diameter (surrounding native cartilage). The thickness of the graft cartilage was varied from 0.33x the thickness of native cartilage (proud graft subchondral bone) to 3x the thickness of native cartilage (sunken graft subchondral bone; Fig. 1). The thickness of the native cartilage was set to 2 mm. The surface of the cartilage in the graft was matched to the surrounding native cartilage. A 1 MPa pressure was applied to the fixed patellar cartilage surface. Scans were segmented using Dragonfly and meshed using HyperMesh. FE simulations were conducted in Abaqus 2019.

The simplified model demonstrated that a high stress region occurred in the cartilage at the sharp bony edge between the graft and native subchondral bone, localized to the region with thinner cartilage. A 20% increase in applied pressure occurs up to 50μm away from the graft edge (primarily in the graft cartilage) for grafts with proud subchondral bone but varies little based on the graft cartilage thickness. For grafts with sunken subchondral bone, the size of the high stress region decreases as the difference between graft cartilage and native cartilage thickness decreases (Fig. 2-4), with a 200 μm high stress region occurring when graft cartilage was 3x thicker than native cartilage (i.e., greater graft cartilage thickness produces larger areas of stress in the surrounding native cartilage). The 3D models reproduced the key features demonstrated in the simplified model. Larger differences between native and graft cartilage thickness cause larger high stress regions. Differences between the 3D and simplified models are caused by heterogeneous cartilage surface curvature and thickness.

Simplified and 3D FE analysis confirmed our hypothesis that greater cartilage thickness mismatches resulted in higher cartilage stresses for sunken subchondral bone. Unexpectedly, cartilage stresses were independent of the cartilage thickness mismatch for proud subchondral bone. These FE findings did not account for tissue remodeling, patient variability in tissue mechanical properties, or complex tissue loading. In vivo experiments with full-thickness strain measurements should be conducted to confirm these findings. Mismatches in the subchondral bone can therefore produce stress increases large enough to cause local chondrocyte death near the subchondral surface. These stress increases can be reduced by (a) reducing the difference in thickness between graft and native cartilage or (b) using a graft with cartilage that is thinner than the native cartilage.

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Limb symmetry on a battery of functional tests is becoming more common as a clinical rehabilitation tool serving as a proxy assessment for readiness to return to sport following anterior cruciate ligament reconstruction (ACLR). The predictive capability of each included test for determining the likelihood of a second ACL injury is not well known. This study combines 14 established functional tests into a comprehensive return-to-sport assessment (RTSA). Study purpose: to determine if any of the functional tests were independently related to a second ACL injury occurring after the patient was cleared for return to sport.

The RTSA was administered to 226 individuals after primary, unilateral ACLR who were followed for at least 24 months (51% female; mean ± SD age, 18.9 ± 4.0 years at RTSA, 9.4 ± 2.4 months post-surgery). The RTSA included 14 tests that involved calculation of Limb Symmetry Indices (LSI): leg press [LP], eccentric hamstring strength [HS], hip adductor strength [HA], Y Balance Test (anterior [YANT], posteromedial [YPM], posterolateral [YPL]), single hop [SH], triple hop [TH], crossover hop [CH], 6 meter timed hop [TiH], lateral hop [LH], medial hop [MH], vertical jump [VJ], single leg squat [SLS]. LSI averaged values of three trials for each leg for LP, HS, HA, SH, TH, CH, TiH, LH, MH, VJ, and SLS. The lowest bilateral difference across three trials was used for YANT, YPM, and YPL. Logistic regression using backward elimination was used to predict the odds of a second non-contact ACL injury using the RTSA, sex, age, and months post-surgery at RTSA as the independent variables.

Twenty-five (11%) patients returned to have a subsequent ACL surgery. Twenty of the 25 experienced a second non-contact ACL injury (70% female; 10 ipsilateral, 10 contralateral). Of the 14 female athletes, there were eight contralateral and six ipsilateral tears. In males, there were two contralateral and four ipsilateral tears. The mean time from surgery to injury was 20.5 ± 9.8 months. Age (OR; 95%CI: 0.75; 0.58, 0.92), LP (0.97; 0.93, 0.99), YANT (1.21; 1.02, 1.43), and TiH (1.10; 1.01, 1.20) were found to be significantly associated with the odds of re-injury.

Age, YANT, and the LSI of LP and TiH have a statistically significant impact on the odds of a second ACL injury after ACL reconstruction. YANT has an OR of 1.21, indicating that a 1cm increase in asymmetry will increase the likelihood of re-injury by 21%, holding all else constant. A 1% increase in the TiH LSI results in a 10% increase in the odds of re-injury. The risk of re-injury decreases as age increases. The OR for LP symmetry was near 1.0 and therefore may not have a clinically relevant effect on re-injury risk. Although LSI is a straightforward, quantitative measure, clinicians should not solely rely on it as a proxy for recovery of knee function. Many tests are available for clinical assessments, but this study found only a few of the tests to have significant associations with a subsequent ACL injury following return to play after ACL reconstruction.

Introduction

Closed avulsion of the Flexor Digitorum Profundus (FDP) from distal phalanx most commonly affects the ring finger when an extensive force is applied to a finger in active flexion. Whilst it is undoubtably reasonable to provide treatment for those who present with symptoms, there may be a cohort of people who sustain an avulsion without noticing. This study aims to quantify the effect of ring finger FDP avulsion on overall grip strength to determine the functional effect of a missed injury

The original RCT demonstrated that a limitedly-supervised post-ACL reconstruction rehabilitation program was both clinically more effective and less costly than the traditional physiotherapy-supervised program. This study contacted patients from the original RCT a minimum of two years post-surgery to evaluate whether or not the clinical findings of the RCT were upheld over the long term. This study of eighty-eight patients has upheld the original findings in that the patients who performed the limitedly-supervised (home-based) program had a significantly higher mean disease-specific quality of life score compared to the patients who performed the physiotherapy-supervised rehabilitation program.

To determine whether or not there were any differences in long-term outcome between those patients who performed a physiotherapy-supervised rehabilitation program (PT) and those who performed a primarily home-based rehabilitation program (H) in the first three months following ACL reconstruction.

Patients were originally randomized, before ACL reconstruction surgery, to either the physiotherapy-supervised (seventeen physiotherapy sessions) or home-based program (four physiotherapy sessions). Eighty-eight of the original patients were able to return two to four years following surgery to assess their long-term clinical outcomes. Primary outcome: the Mohtadi ACL disease-specific quality of life questionnaire (ACL QOL). Secondary outcomes: bilateral difference in knee extension and flexion range of motion, sagittal plane knee laxity, relative quadriceps and hamstrings strength, and IKDC score. Unpaired t-tests were used to compare the two groups across the continuous variables. A Chi square test was used for the categorical data.

The home-based group had a significantly higher (p = 0.02, 95% CI [18.4, 1.7]) mean ACL QOL score (80.0 ± 16.2) compared to the physiotherapy-supervised group (69.9 ± 22.0) a mean of forty months post-surgery. There were no significant differences between the two groups with respect to any of the secondary outcome measures.

This long-term study upholds the short-term findings of the original RCT in that the home-based rehabilitation program is more effective than a more physiotherapy-intensive program for patients in the first three months following ACL reconstruction.

Given the resource savings demonstrated in the original RCT, the home-based program is clearly economically-dominant (i.e., clinically more effective and less expensive).

FUNDING: Calgary Health Region