Quantitative localization of the entry point of the lateral ascending branch of the anterior circumflex humeral artery: a high definition CT-scan radiological study.

PURPOSE: To define the localization of the entry point of the lateral ascending branch of the anterior circumflex humeral artery (LACHA) for better surgical management and prevention of injury to this important vessel. The hypothesis is that the insertion point of the artery will be constant in subjects. METHODS: A retrospective study of 27 tomographic images was conducted to generate a three-dimensional (3D) model and localize the entry point of the LACHA. Using a coordinate system consisting of three axes: the proximal-distal axis (PDA), the anterior-posterior axis (APA) and the medial-lateral axis (MLA), the position of a foramen located in the superior portion of the bicipital groove and representing the entry point of LACHA was measured on each reconstructed model. RESULTS: On average, the foramen was located 10.0 mm distal along the PDA from the most proximal point of the greater tuberosity (GT). Along the MLA and with respect to the most medial portion of the GT, the foramen was located 3.4 mm medially, on average. No significant differences between men and women or between sides for foramen position measurements were found. CONCLUSION: Unnecessary procedures to the proximal biceps, aiming to prevent chronic pain, should be avoided in fracture fixation as they would affect a significant source of blood supply to the humeral head. These findings could help surgeons protect the only vascular supply they can during the fixation of proximal humeral fractures, when using the anterior or antero-lateral approaches.

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.

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).

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.

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.

Intraoperative Torque Test to Assess Syndesmosis Instability.

BACKGROUND:: In this cadaveric study, a new "torque test" (TT) stressing the fibula posterolaterally under direct visualization was compared with the classical external rotation stress test (ERT) and lateral stress test (LST). METHODS:: The anteroinferior tibiofibular ligament (AiTFL), the interosseous membrane (IOM), and the posteroinferior tibiofibular ligament (PiTFL) were sectioned sequentially on 10 fresh-frozen human ankles. At each stage of dissection, instability was assessed using the LST, ERT, and TT under direct visualization. Anatomical tibiofibular diastasis measurements were taken directly on cadavers and compared using the Wilcoxon signed rank test. RESULTS:: All 3 tests showed statistically significant motion in the syndesmosis when at least 2 ligaments were sectioned. The mean increase across diastasis with a 2-ligament section was 3.0 mm ( P = .005), 3.2 mm ( P = .005), and 4.8 mm ( P = .005) for the LST, ERT, and TT, respectively. The largest mean increase in diastasis was obtained with a complete injury using the TT and was 6.2 mm ( P = .008). With the TT, a 3.5-mm tibiofibular diastasis was 90% sensitive and 100% specific when 2 or more syndesmotic ligaments were sectioned. CONCLUSION:: The TT was a more sensitive and specific tool for detecting syndesmosis instability than classic LST and ERT. CLINICAL RELEVANCE:: Stressing the fibula in a posterolateral direction created a larger distal tibiofibular diastasis, which would be easier to detect in the intraoperative setting. The TT was more sensitive and specific to detecting a 2-ligament syndesmotic injury than the classic test and required less force to perform.

A New and More Sensitive View for the Detection of Syndesmotic Instability.

OBJECTIVES: We hypothesize that a single syndesmotic view, capturing both sagittal and coronal tibiofibular displacement, will be more sensitive than a mortise view to detect syndesmotic instability. METHODS: Ten fresh frozen human lower limbs were used to test the new syndesmotic view with simulated syndesmosis injury. The anteroinferior tibiofibular ligament, interosseous membrane, and posteroinferior tibiofibular ligament were sectioned sequentially. At each stage, the syndesmosis was tested using the external rotation stress (ERS) test and lateral stress test (LST). For each stress condition, a true mortise view and the new syndesmotic view were performed. Medial clear space and tibiofibular clear space (TFCS) were measured on a mortise view, and TFCS was measured on a syndesmotic view (TFCS-s). Wilcoxon signed-rank tests were used to compare measurements. RESULTS: Syndesmotic view enabled instability detection with a 2-ligament dissection at a mean increase in TFCS-s of 2.37 mm (P = 0.021) and 1.98 mm (P = 0.011), using the ERS and LST, respectively. TFCS on the mortise view was significantly different only with a complete injury. Medial clear space did not vary significantly with injury increments. Sensitivity was 66% and 61% using ERS and LST, respectively, for the TFCS-s, compared with 27% and 33%, respectively, for the TFCS. Specificity was similar for TFCS and TFCS-s. CONCLUSIONS: This study was able to demonstrate that the syndesmotic view is more sensitive than the mortise view in detecting syndesmotic instability in a cadaveric model. It is particularly helpful to uncover instability secondary to an incomplete syndesmosis injury requiring fixation.

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.

Direct visualization of the syndesmosis for evaluation of syndesmotic disruption: A cadaveric study.

OBJECTIVES: Radiologic criteria for syndesmosis instability evaluation remain controversial and direct visualization (DV) of the distal tibiofibular articulation is an alternative diagnostic method worthy of further investigation. We speculate that DV is a more accurate way to evaluate syndesmosis instability than fluoroscopy. The purpose of this study is to determine whether syndesmosis instability can accurately be recognized through DV and if this new intraoperative diagnostic method is more sensitive than fluoroscopy in detecting syndesmosis instability. METHODS: Ten cadaveric ankles were tested using a sequential iatrogenic syndesmosis injury model. Specimens were tested incrementally with the lateral stress test (LST) and the external rotation stress test (ERT). The resulting instability was measured directly and fluoroscopically with a true mortise view by using medial clear space (MCS) and tibiofibular clear space (TFCS). RESULTS: DV detected a 2-ligaments injury at a mean diastasis of 3.02 mm (P = 0.0077) and 3.19 mm (P = 0.0077) with the LST and ERT, respectively. Fluoroscopically, TFCS showed a significant diastasis only with a complete syndesmosis rupture while MCS did not show any significant differences. CONCLUSIONS: DV of the syndesmosis in a cadaver injury model appears to be more sensitive than fluoroscopy in identifying injury, especially incomplete syndesmotic disruption.

Braided tape is equivalent to modified Mason-Allen multi-strand #2 suture in subscapularis muscle repair: results of a biomechanical study.

BACKGROUND: To help determine the optimal fixation method for subscapularis tendon repair in arthroplasty, the present study compares single-passage transosseous tape (BT) and modified Mason-Allen #2 suture (MA). METHODS: Eighteen human cadaveric shoulders were randomized to two repair constructs after arthroplasty preparation. Both techniques included two transosseous passages through the bicipital groove and then through the tendon at the level of the anatomical neck. Construct was tested using a traction machine, measuring cyclic loading and ultimate load to failure. RESULTS: The mean age of our specimens was 71 years. No significant difference was observed between the repair techniques in both mean ultimate load and cyclic loading. The mean (SD) ultimate load (UL) for BT was 293 (84) N and 342 (117) N for MA, which was not statistically significant (p = 0.374). The majority of repairs failed in the tendon. Bone cut-out was observed with the MA but not for the BT repair. No correlation was found between bone density and UL for BT (r = -0.09) but there was strong correlation for MA (r = 0.63). CONCLUSIONS: The MA repair appears to be more dependant on bone mineral density for ultimate load, indicating that braided-tape might be better suited for osteoporotic patients to avoid bone cut-out.

Measurement of combined glenoid and Hill-Sachs lesions in anterior shoulder instability.

BACKGROUND: Recurrent glenohumeral anterior instability (RGAI) frequently induces combined glenoid and Hill-Sachs bone lesions and is a risk factor for soft tissue repair failure. This cohort study describes a simple preoperative quantification method for bone loss, the Clock method, the first that combines glenoid and humeral lesions. METHODS: Computed tomography scans of 34 shoulders with RGAI were twice reviewed by three independent observers, who measured bone lesions using the new Clock method and existing validated methods. Intra- and inter-observer reliability of the Clock method was evaluated (intraclass correlation coefficient). Pearson correlation was used to correlate Clock method with existing methods, and with function (Western Ontario Shoulder Instability, Quick-Disabilities of the Arm, Shoulder and Hand). RESULTS: Thirty-two patients met the inclusion criteria: three females and 29 males, mean age 28 years. The intra- and inter-observer reliability was excellent, with intraclass correlation coefficient ranging from 0.817 to 0.938 for the novel Clock method. Humeral Clock and Glenoid Clock strongly correlated with Humeral Ratio (r = 0.882, p < 0.001) and Glenoid Surface Area and Glenoid Ratio (r = 0.793 and 0.717, p < 0.001), respectively. The classic threshold of 25% of the glenoid diameter with the Glenoid Ratio method corresponds to 4 hours with the Glenoid Clock method. CONCLUSIONS: The Clock method is quick and reliable, with more studies being needed to investigate whether it is correlated with surgical outcomes.

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 analysis of traumatic mesenteric avulsion.

Mesenteric avulsion, corresponding to a tearing of intestine's root, generally results from high deceleration in road accidents. The biomechanical analysis of bowel and mesenteric injuries is a major challenge for injury prevention, particularly because seat belt restraint may paradoxically increase their risk of occurrence. The aim of this study was to identify the biomechanical behavior of mesentery and small bowel (MSB) tissue samples under dynamical loading conditions. A dedicated test bench was designed in order to perform tensile tests on fresh MSB porcine specimens, with quasi-static (1 mm/s) and dynamic (100 mm/s) loading conditions. The mechanical behavior of MSB specimens was investigated and compared to isolated mesenteric and isolated small bowel specimens. The results show a high sensitivity of MSB stiffness (1.0 ± 0.2 and 1.3 ± 0.3 N/mm at 1 and 100 mm/s, p = 0.001) and ultimate force (22 ± 5 and 35 ± 8 N at 1 and 100 mm/s, p = 0.001) to the loading rate but not for the displacement at failure. This leads to postulate on a failure criteria based on strain level regardless of the strain rate. These experimental results could be further used to develop refined finite element models and to further investigate on injury mechanisms associated to seat belt restraints, as well as to evaluate and improve protective devices.

Braided tape suture provides superior bone pull-through strength than wire suture in greater tuberosity of the humerus.

INTRODUCTION: The purpose of this study is to compare the pull-through strength of transosseous braided tape suture with wire suture in proximal humeri bones (greater tuberosity). METHODS: A biomechanical study on eight cadaveric human specimens where two transosseous sutures were randomly applied on each specimen (anterior and posterior). Force/displacement curves were obtained for each specimen and the maximum pull-through load was noted. RESULTS: There is a significant difference in maximal pull-through strength favoring braided tape suture over wire suture. CONCLUSIONS: Transosseous braided tape suture provides almost twice the bone pull-through strength and is slightly correlated to volumetric bone mineral density.

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.

Locking plate fixation provides superior fixation of humerus split type greater tuberosity fractures than tension bands and double row suture bridges.

BACKGROUND: This paper aims to determine the strongest fixation method for split type greater tuberosity fractures of the proximal humerus by testing and comparing three fixation methods: a tension band with No. 2 wire suture, a double-row suture bridge with suture anchors, and a manually contoured calcaneal locking plate. METHODS: Each method was tested on eight porcine humeri. A osteotomy of the greater tuberosity was performed 50° to the humeral shaft and then fixed according to one of three methods. The humeri were then placed in a testing apparatus and tension was applied along the supraspinatus tendon using a thermoelectric cooling clamp. The load required to produce 3mm and 5mm of displacement, as well as complete failure, was recorded using an axial load cell. FINDINGS: The average load required to produce 3mm and 5mm of displacement was 658N and 1112N for the locking plate, 199N and 247N for the double row, and 75N and 105N for the tension band. The difference between the three groups was significant (P<0.01). The average load to failure of the locking plate (810N) was significantly stronger than double row (456N) and tension band (279N) (P<0.05). The stiffness of the locking plate (404N/mm) was significantly greater than double row (71N/mm) and tension band (33N/mm) (P<0.01). INTERPRETATION: Locking plate fixation provides the strongest and stiffest biomechanical fixation for split type greater tuberosity fractures.