Effect of a Controlled Ankle Motion Walking Boot on Syndesmotic Instability During Weightbearing: A Cadaveric Study.

BACKGROUND: Syndesmotic injuries can lead to long-term complications; hence, they require careful management. Conservative treatment is adequate when 1 syndesmotic ligament is injured, but surgery is often necessary to achieve articular congruity when 3 syndesmotic ligaments are ruptured. However, there is some controversy over the best treatment for 2-ligament injuries. PURPOSE: To evaluate the effect of a controlled ankle motion (CAM) walking boot on syndesmotic instability following iatrogenic isolated anterior inferior tibiofibular ligament (AiTFL) injury and combined AiTFL/interosseous ligament (IOL) injuries in a cadaveric simulated weightbearing model. STUDY DESIGN: Controlled laboratory study. METHODS: Ten cadaveric specimens were dissected to expose the tibial plateau and syndesmosis. The specimens were fitted to a custom-made device, and a reproducible axial load of 750 N was applied. Iatrogenic rupture of the syndesmotic ligaments (AiTFL + IOL) was done sequentially. Uninjured syndesmoses, isolated AiTFL rupture, and combined AiTFL/IOL rupture were compared with and without axial loading (AL) and CAM boot. The distal tibiofibular relationship was evaluated using a previously validated computed tomography scan measurement system. Wilcoxon tests for paired samples and nonparametric data were used. RESULTS: The only difference noted in the distal tibiofibular relationship during AL was an increase in the external rotation of the fibula when using the CAM boot. This was observed with AiTFL rupture (8.40° vs 11.17°; P = .009) and combined AiTFL/IOL rupture (8.81° vs 11.97°; P = .005). CONCLUSION: AL did not cause a significant displacement between the tibia and fibula, even when 2 ligaments were ruptured. However, the CAM boot produced a significant external rotation with 1 or 2 injured ligaments. CLINICAL RELEVANCE: Further studies are needed to assess the capacity of the CAM walking boot to prevent malreduction when external rotation forces are applied to the ankle. Moreover, special care should be taken during the fitting of the CAM boot to avoid overinflation of the cushions.

Suture bridge transosseous equivalent repair is stronger than transosseous tied braided-tape.

BACKGROUND: This study biomechanically compares two methods of supraspinatus repair: single row transosseous braided-tape (BT) and suture bridge transosseous equivalent (SBTE) with 2 medial anchors and 2 lateral anchors. The purpose is to test the hypothesis that BT provides superior or equal biomechanical strength compared to SBTE. METHODS: Nine pairs of frozen cadaveric shoulders were selected and both repair techniques were tested on each pair, using a biomechanical testing unit to measure cyclic loading and ultimate load to failure. Moreover, tendon displacement was measured using the percentage of footprint exposed during the cyclic loading phase. RESULTS: Mean specimen age was 71 years (6 males, 3 females), and mean volumetric bone mineral density was 134 mg/cm3. BT mean ultimate load was 266 ± 81 Newton (N) compared to 398 ± 69 N for SBTE and this difference of 131 N was statistically significant p = 0.025. There was a strong positive correlation between bone mineral density and SBTE construct ultimate load. The difference between the percentage of footprint exposed after cyclic loading of the two repairs was statistically significant with the exception of the 10-80 N load (p < 0.05). The failure mode was suture cutout through the tendon in 88% (7/8) of specimens for both techniques. CONCLUSION: SBTE repair with bone anchors provides superior biomechanical strength compared to BT repair in terms of ultimate load and cyclic loading. The tendon-suture junction is the weakness of both methods. These models simulate a complete tear with total loss of contact with rotator interval and infraspinatus. Future studies could focus on a more isolated physiologic supraspinatus tear pattern. LEVEL OF EVIDENCE: Basic science study (Level II).

Three-dimensional analysis of the locked position in patients with recurrent shoulder instability.

BACKGROUND: Although recurrent anterior shoulder instability (RASI) is a common condition in young patients, no studies to date have measured the 3-dimensional (3D) locked position of the glenohumeral joint during an anterior dislocation. Therefore, our goal was to estimate it with 3D computed tomography (CT) scans. METHODS: Patients in this prospective observational study were separated in 3 groups: normal laxity, hyperlaxity, and epilepsy. They were characterized by questionnaires (Western Ontario Shoulder Instability Index, 11-item version of the Disabilities of the Arm, Shoulder and Hand, and Beighton Laxity Score), and a CT scan revealing bipolar bone defects. 3D models of the humeral head and the glenoid were reconstructed from the CT scan, and the rotations and displacements of the humerus relative to the glenoid, from initial to locked position, were calculated. Intraobserver and interobserver reliability by intraclass correlation coefficient (ICC), analysis of variance test, and the Pearson correlation were used to evaluate data. RESULTS: This study involved 44 patients (46 shoulders): 18 with "normal" laxity, 18 with hyperlaxity and 8 (2 bilateral) with epilepsy. The mean locked position was of 12° of abduction, 90° of external rotation, and 21° of extension. The intraobserver and interobserver reliability was excellent for all the rotations and displacements (ICCs, 0.751-0.977) except the proximal-distal displacement (ICCs, 0.409-0.688). Significant differences were found for external rotation, anterior displacement, and medial displacement among the 3 groups of patients. Correlation was found between locked position and function. CONCLUSIONS: This study produced highly reliable measurements, with abduction angles proving to be lower than expected. Future work should focus on the effect of this low abduction angle on Hill-Sachs lesion management.

Impact of olecranon fracture malunion: Study on the importance of PUDA (Proximal Ulna Dorsal Angulation).

PURPOSE: The Proximal Ulna Dorsal Angulation (PUDA) is part of the proximal ulna's normal anatomy. The importance of restoring ulnar anatomy characteristics precisely after olecranon fracture is not known, however, failure to recreate the PUDA after surgery may result in poorer functional outcomes. The purpose of this study is to evaluate the impact of minimal proximal ulna malunion on elbow ROM and function at least one year after olecranon ORIF. METHOD: A retrospective comparative cohort study took place in three level-1 trauma centers. Forty-nine adult volunteers who underwent ORIF for olecranon fracture were included. Patients were separated into two groups according to PUDA malreduction-defined as more than 5° of difference between the fractured and the contralateral elbow. OUTCOME MEASUREMENTS: Radiographic ROM measurement, demographic data and quality of life questionnaires were recorded (PREE, MEPS, Q-DASH, SF12, VAS). RESULTS: The mean follow up was 3 years and 9 months (1-7 years). There was no difference in terms of outcome, quality of reduction or range of motion between patients treated with plate or tension band. The mean PUDA on the fracture side was different from the normal side (2.20 vs 4.90, p<0.001). Fourteen patients (29%) had PUDA malunion. Those patients had decreased elbow flexion (-7°, p=0.011), extension (-11.2°, p=0.013) and total ROM (-18.6°, p=0.006) as opposed to the control group. Both groups had comparable quality of life questionnaire scores. Alcohol consumption was the only risk factor associated with worse scores. CONCLUSION: Incidence of olecranon malunion-as defined by PUDA measurement - was 29% and it was associated with decreased elbow range of motion. Alcohol consumption was correlated with a worse prognosis in our series of patients. Tension band and plate fixation can maintain a good reduction in terms of PUDA and the choice of fixation method does not influence outcome. LEVEL OF EVIDENCE: III Therapeutic study.

Biomechanical study comparing 3 fixation methods for rotator cuff massive tear: Transosseous No. 2 suture, transosseous braided tape, and double-row.

BACKGROUND: Important rotator cuff repair failure rates have prompted this study of the techniques and materials used in order to optimize clinical results. QUESTIONS/PURPOSES: Is the reconstruction of the rotator cuff biomechanically stronger when using: 1) transosseous with 2 mm braided tape suture (TOT), 2) transosseous with multi-strand No. 2 sutures (TOS), or 3) double row suture bridge with suture anchors loaded with No. 2 braided sutures (DRSB)? METHODS: Twenty-four cadaveric pig shoulders were randomized in the three repair constructs. The infraspinatus muscle was detached to mimic a complete laceration, repaired with one of the three repair groups and tested with a traction machine. Cameras recorded tendon displacement during trials. The ultimate strength (US), failure mode, and tendon displacement, qualified by the bare footprint area (BFA), during cycling phases were compared. RESULTS: The US for DRSB was 175 ± 82 Newton (N), 91 ± 51 N for TOS, and 147 ± 63 N for TOT. The BFA after 200 cycles was 81 ± 34% for TOS, 57 ± 41% for TOT, and 26 ± 27% for DRSB repairs. No significant difference was observed between the DRSB and TOT results for US or BFA percentage of loss during all the cycling phases. TOS proved to be weaker than TOT and DRSB. CONCLUSION: All the ruptures occurred in the tendon, which seems to be the weakness of rotator cuff repairs. The use of braided tape suture with a transosseous technique seems to be a cost effective, equivalent alternative implant compared to anchor fixation.

Transosseous braided-tape and double-row fixations are better than tension band for avulsion-type greater tuberosity fractures.

INTRODUCTION: The optimal treatment for avulsion-type greater tuberosity fractures is yet to be determined. Three fixation methods are tested: tension band with #2 wire suture (TB), double-row suture bridge with anchors (DR), and simple transosseous fixation with braided tape (BT). MATERIALS AND METHODS: Twenty-four porcine proximal humeri were randomised into three groups: TB, DR and BT. A standardised greater tuberosity (GT) osteotomy was performed at 90° to the humeral diaphysis axis. A mechanical testing machine was used to simulate supraspinatus contraction. The force required to produce 3mm and 5mm displacement, as well as complete failure was measured with an axial load cell. Also, three cycles of shoulder flexion/extension with 25 N of supraspinatus contraction were performed. Maximum GT fragment translation and rotation amplitude during one cycle were measured. RESULTS: During supraspinatus contraction, DR and BT groups (p < 0.05) were superior to TB group for both displacements. The BT technique had the strongest maximal load to failure (BT = 466 N; DR = 386 N; TB = 320 N). For the flexion/extension, DR and BT groups had less displacement and rotation than TB group (anterio-posterior displacement: BT = 2.0mm, DR = 1.9 mm, TB = 5.8 mm; anterio-posterior angular displacement: BT = 1.4°, DR = 1.0°, TB = 4.8°). No significant difference was observed between DR and BT groups, except for the medio-lateral rotation favouring the DR group. CONCLUSION: In conclusion, BT and DR are good fixation methods to treat displaced avulsion-type greater tuberosity fractures. They have similar mechanical properties, and are stronger and more stable that the TB construct. Potential advantages of the BT over the DR may be a lower cost and easier surgery. LEVEL OF EVIDENCE: Basic science study (LEVEL II).

Anterior locking plate reduces trochanteric fracture migrations during hip extension.

BACKGROUND: Greater trochanter fractures or osteotomies fixed with lateral plates still present high rates of complications. Unblocked greater trochanter anterior movement during hip extension might be a possible cause of failure. This study aimed to determine, under stair climbing conditions, the biomechanical behaviour of a greater trochanter fragment and the impact of an anterior locking plate on its migration. METHODS: Eighteen femurs paired from nine fresh frozen cadaveric specimens were tested on a quasi-dynamic stair climbing cycling test bench. Left and right sides with greater trochanter fractures were randomly fixed either with an antero-lateral locking plate or with a lateral locking plate. Migrations, defined as the remaining movements of the unloaded greater trochanter fragment, were measured for all 18 femurs. FINDINGS: During hip extension, multi-directional greater trochanter fragment movements occurred and showed a back-and-forth anterior rotation. The lateral locking plate failed due to greater trochanter fragment rotation around the superior axis and anterior translation. The antero-lateral locking plate significantly reduced greater trochanter anterior migration (-0.9 mm ± 1.6) compared to the lateral locking plate (9.6 mm ± 9.5). INTERPRETATION: Hip extension provides a plausible explanation for the high rate of post-operative failures of greater trochanter fixations. An antero-lateral locking plate represents an efficient surgical alternative counteracting the multi-directional greater trochanter movements occurring during hip extension.

Initial tension loss in cerclage cables.

Cerclage cables, frequently used in the management of fractures and osteotomies, are associated with a high failure rate and significant loosening during surgery. This study compared the capacity to maintain tension of different types of orthopaedic cable systems. Multifilament Cobalt-Chrome (CoCr) cables with four different crimp/clamp devices (DePuy, Stryker, Zimmer and Smith&Nephew) and one non-metallic Nylon (Ny) cable from Kinamed were instrumented with a load cell to measure tension during insertion. Significant tension loss was observed with crimping for all cables (P<0.05). Removing the tensioner led to an additional unexpected tension loss (CoCr-DePuy: 18%, CoCr-Stryker: 29%, CoCr-Smith&Nephew: 33%, Ny: 46%, and CoCr-Zimmer: 52%). The simple CoCr (DePuy) cable system outperformed the more sophisticated locking devices due to its significantly better ability to prevent tension loss.