The Kouvalchouk Procedure versus Distal Tibial Allograft for Treatment of Posterior Shoulder Instability: The Deltoid "Hammock" Effect Exists.

BACKGROUND: In 1993, Kouvalchouk described an acromial bone block with a pedicled deltoid flap for the treatment of posterior shoulder instability. This procedure provides a "double blocking" effect in that the acromial autograft restores posterior glenoid bone loss and the deltoid flap functions as a muscular "hammock" resembling the sling effect of the conjoint in the Latarjet procedure. The primary aim of this study was to compare the Kouvalchouk procedure to distal tibial allograft (DTA) reconstruction for the management of posterior shoulder instability with associated bone loss, while the secondary aim was to evaluate the deltoid hammock effect. s METHODS: Ten upper extremity cadavers were evaluated using a validated shoulder testing apparatus in 0° and 60° of glenohumeral abduction in the scapular plane. Testing was first performed on the normal shoulder state and was followed by the creation of a 20% posterior glenoid defect. Subsequently, the Kouvalchouk and DTA procedures were conducted. Forces of 0N, 5N, 10N and 15N were applied to the posterior deltoid tendinous insertion on the Kouvalchouk graft along the physiological muscle line-of-action to evaluate the 'hammock" effect of this procedure. Testing was additionally performed on the Kouvalchouk bone graft with the deltoid muscle sectioned from its bony attachment. For all test states, a posteriorly directed force was applied to the humeral head perpendicular to the direction of the glenoid bone defect, with the associated translation quantified using an optical tracking system. The outcome variable was posterior translation of the humeral head at an applied force magnitude of 30N. RESULTS: The Kouvalchouk procedure with the loaded deltoid flap (10N: P=0.039 and 15N: P<0.001) was significantly better at reducing posterior humeral head translation than the DTA. Overall, increased glenohumeral stability was observed with increased force applied to the posterior deltoid flap in the Kouvalchouk procedure. The 15N Kouvalchouk was most effective at preventing posterior humeral translation, and the difference was statistically significant compared with the 20% glenoid defect (P=0.003), detached Kouvalchouk (P<0.001), and 0N Kouvalchouk (P<0.001). The 15N Kouvalchouk procedure restored posterior shoulder joint stability to near normal levels, such that it was not significantly different from the intact state (P=0.203). CONCLUSIONS: The Kouvalchouk procedure with load applied to the deltoid was found to be biomechanically superior to the DTA for the management of posterior shoulder instability with associated bone loss. Additionally, the results confirmed the presence and effectiveness of the deltoid "hammock" effect.

Bridge Plating is an Effective Adjunct Treatment for Complex Elbow Instability.

BACKGROUND: Managing persistent elbow instability and chronic dislocations presents challenges despite traditional treatments. Supplementary methods like immobilization and various fixations, though common, can carry high complication rates. This study assesses the efficacy of bridge plating in treating complex elbow instability through a retrospective review of patients. Data on characteristics, treatment duration, range of motion, complications, and evaluation scores were analyzed, providing insights into outcomes complications associated with bridge plating. RESULTS: Eleven patients were reviewed at an average follow-up of 80 ± 68 weeks. postoperatively. The average age was 53±14 years and there were 5 females and 6 males. The average BMI was 38. Bridge plating was used for a spectrum of complex elbow injuries. The average time from injury to bridge plating in acute cases was 29±19 days and 344±381 days in chronic cases. The average duration of bridge plating was 121 ± 72 days. At the time of plate removal, mean intraoperative elbow motion was extension 58±12°, flexion 107±14°, supination 66±23° and pronation 60±26°. At the latest follow-up visit, average elbow motion was extension 37±22°, Flexion 127± 17°, supination 72±15° and pronation 63±18°. There were 6 complications (55%); heterotopic ossification, ulnar neuropathy, wound failure over the plate in a thin patient, an ulnar shaft peri-prosthetic fracture due to a seizure induced fall, and elbow subluxation despite bridge plate fixation. One patient sustained a fracture of a 3.5mm locking bridge plate. One patient required a contracture release for persistent stiffness. Four of these complications can be directly attributed to the use of the bridge plate (36%). At final follow-up, the average patient rated elbow evaluation score was 34, with 0 indicating no pain and disability. The average single assessment numeric evaluation score was 66% for the 8 patients who had this available, with 100% being the best possible attainable score. CONCLUSION: Bridge plating effectively maintains joint reduction in selected complex elbow instability cases. However, patients with bridge plates often require a second surgery for removal and experience high rates of general complications due to the complexity of their condition.

The sizing and suitability of nonspherical ellipsoid humeral heads for total shoulder arthroplasty.

BACKGROUND: Total shoulder arthroplasty (TSA) implants have evolved to include more anatomically shaped components that better replicate the native state. The geometry of the humeral head is nonspherical, with the frontal diameter of the base of the head being up to 6% larger than the sagittal diameter. Despite this, most TSA humeral head implants are spherical, meaning that the diameter must be oversized to achieve complete coverage, resulting in articular overhang, or portions of the resection plane will remain uncovered. It is suggested that implant-bone load transfer between the backside of the humeral head and the cortex on the resection plane may yield better load-transfer characteristics if resection coverage were properly matched without overhang, thereby mitigating proximal stress shielding. METHODS: Eight paired cadaveric humeri were prepared for TSA by an orthopedic surgeon who selected and prepared the anatomic humeral resection plane using a cutting guide and a reciprocating sagittal saw. The humeral head was resected, and the resulting cortical boundary of the resection plane was digitized using a stylus and an optical tracking system. To simulate optimal sizing of both circular and elliptical humeral heads, both circles and ellipses were fit to the traces. Two extreme scenarios were also investigated: upsizing until 100% total coverage and downsizing until 0% overhang. RESULTS: By switching from a spherical (circular) to an ellipsoid (elliptical) humeral head, a small, 2.3% ± 0.3% increase in total coverage occurred (P < .001), which led to a large, 19.5% ± 1.3% increase in cortical coverage (P < .001). Using a circular head resulted in 2.0% ± 0.1% greater overhang (P < .001), defined as a percentage of the total enclosed area that exceeded the bounds of the humeral resection. As a result of increasing the head size until 100% resection coverage occurred, the ellipse produced 5.4% ± 3.5% less overhang than the circle (P < .001). When the head size was decreased until 0% overhang occurred, total coverage was 7.5% ± 2.8% greater for the ellipse (P < .001) and cortical coverage was 7.9% ± 8.2% greater for the ellipse (P = .01). Cortical coverage was greater for circular heads when the head size was shrunk below -2.25% of the optimal fitted size. DISCUSSION: Reconstruction with ellipsoid humeral heads can provide greater total resection and cortical coverage than spherical humeral heads while avoiding excessive overhang; however, cortical coverage can be inferior when undersized. These initial findings suggest that resection-matched humeral heads may yield benefits worth pursuing in the next generation of TSA implant design.

The effect of humeral head positioning and incomplete backside contact on bone stresses following total shoulder arthroplasty with a short humeral stem.

BACKGROUND: The use of uncemented humeral stems in total shoulder arthroplasty (TSA) is known to be associated with stress shielding. This may be decreased with smaller stems that are well-aligned and do not fill the intramedullary canal; however, the effect of humeral head positioning and incomplete head backside contact has not yet been investigated. The purpose of this study was to quantify the effect of changes in humeral head position and incomplete head backside contact on bone stresses and expected bone response following reconstruction. METHODS: Three-dimensional finite element models of 8 cadaveric humeri were generated, which were then virtually reconstructed with a short-stem implant. An optimally sized humeral head was then positioned in both a superolateral and inferomedial position for each specimen that was in full contact with the humeral resection plane. Additionally, for the inferomedial position, 2 incomplete humeral head backside contact conditions were simulated whereby contact was defined between only the superior or inferior half of the backside of the humeral head and the resection plane. Trabecular properties were assigned based on computed tomography attenuation and cortical bone was applied uniform properties. Loads representing 45° and 75° of abduction were then applied, and the resulting differentials in bone stress versus the corresponding intact state and the expected time-zero bone response were determined and compared. RESULTS: The superolateral position reduced resorbing potential in the lateral cortex and increased resorbing potential in the lateral trabecular bone, while the inferomedial position produced the same effects but in the medial quadrant. For the inferomedial position, full backside contact with the resection plane was best in terms of changes in bone stress and expected bone response, although a small region of the medial cortex did experience no load transfer. The implant-bone load transfer of the inferior contact condition was concentrated at the midline of the backside of the humeral head, leaving the medial aspect largely unloaded as a result of the lack of lateral backside support. DISCUSSION: This study shows that inferomedial humeral head positioning loads the medial cortex at the cost of unloading the medial trabecular bone, with the same occurring for the superolateral position except that the lateral cortex is loaded at the cost of unloading the lateral trabecular bone. Inferomedial positioned heads also were predisposed to humeral head lift-off from the medial cortex, which may increase the risk of calcar stress shielding. For the inferomedial head position, full contact between the implant and resection plane was preferable.

Indomethacin for heterotopic ossification prophylaxis following surgical treatment of elbow trauma: a randomized controlled trial.

BACKGROUND: Heterotopic ossification is a frequent complication following surgical treatment of elbow trauma. The use of indomethacin to prevent heterotopic ossification is reported in the literature; however, its effectiveness is controversial. The purpose of this randomized, double-blind, placebo-controlled study was to determine whether indomethacin is effective in reducing the incidence and severity of heterotopic ossification after surgical management of elbow trauma. METHODS: Between February 2013 and April 2018, 164 eligible patients were randomized to receive postoperative indomethacin or placebo medication. The primary outcome was the incidence of heterotopic ossification on elbow radiographs at 1-year follow-up. Secondary outcomes included the Patient Rated Elbow Evaluation score, Mayo Elbow Performance Index score, and Disabilities of the Arm, Shoulder and Hand score. Range of motion, complications, and nonunion rates were also obtained. RESULTS: At 1-year follow-up, there was no significant difference in the incidence of heterotopic ossification between the indomethacin group (49%) and the control group (55%) (relative risk, 0.89; P = .52). There were no significant differences in postoperative Patient Rated Elbow Evaluation, Mayo Elbow Performance Index, and Disabilities of the Arm, Shoulder and Hand scores or range of motion (P = .16). The complication rate was 17% in both the treatment and control groups (P > .99). There were no nonunions in either group. CONCLUSION: This Level I study demonstrated that indomethacin prophylaxis against heterotopic ossification in the setting of surgically treated elbow trauma was not significantly different from placebo.

Outcomes of radial head implants in total elbow arthroplasty.

BACKGROUND: There is no consensus on the management of the radial head in total elbow arthroplasty (TEA). In 3-part TEA designs, options include radial head retention, excision, or arthroplasty. Biomechanical studies suggest improved varus-valgus stability with radial head implants in unlinked total elbows. Unfortunately, complications with radial head implants have been common with historical designs. The aim of this study was to evaluate the clinical and radiographic outcomes of radial head implants in a current 3-part TEA and identify risk factors for mechanical failure. METHODS: We performed a retrospective review of radial head implants with a 3-part convertible TEA from 2001 to 2016. Clinical outcomes, functional scores, and radiographic outcomes were recorded. The preoperative radiocapitellar alignment was measured using the radiocapitellar ratio (RCR). Statistics include descriptive statistics, t tests, logistic regression, and Kaplan-Meier survival curves. RESULTS: We identified 44 TEAs in 40 patients, with a mean follow-up period of 7.2 years. The average age at surgery was 58 ± 11 years; 80% of the TEAs were performed in women. The indication for surgery was rheumatoid arthritis in 86%; of the implants, 61% were unlinked. The average preoperative RCR was 10.7 ± 17.9. Postoperatively, 2 radial head implants (5%) were subluxated, 6 (14%) were dissociated, and 2 (5%) were dissociated with implant dislocation on radiographic review. The revision rate for radial head subluxation, dissociation, or dislocation was 7% (n = 3). Univariate logistic regression showed that male sex (P = .002), abnormal preoperative RCR (P = .02), linked implant (P = .03), and older age (P = .04) were risk factors for radial head subluxation, dissociation, or implant dislocation. A multivariate model with all 4 variables did not demonstrate statistical significance. CONCLUSION: The incidence of radial head arthroplasty subluxation, dissociation, or implant dislocation was high (23%). In a univariate logistic regression model, male sex, abnormal preoperative RCR, and linked implants were all statistically significant risk factors for mechanical failure of the radial head implant. Our multivariate model did not show any statistically significant independent risk factors. Polyethylene wear or loosening of the radial head implants was not observed in this study; failure of the bipolar linkage was the principal mode of failure. Although further study is required, caution should be used when considering inserting a radial head implant in male patients with significant preoperative radiocapitellar malalignment. Radial head subluxation or dissociation is not an absolute indication for revision in an asymptomatic patient. Improvements in radial head implant designs in TEA are needed.

Vancomycin is effective in preventing Cutibacterium acnes growth in a mimetic shoulder arthroplasty.

BACKGROUND: Intra-incisional deposition of vancomycin powder is a strategy to limit Cutibacterium acnes infection after shoulder surgery. Unfortunately, limited research exists examining the effectiveness of vancomycin in a clinically relevant joint infection model. This basic science study investigated the efficacy of vancomycin administration as prophylaxis for C acnes growth in vitro using a mimetic shoulder arthroplasty. METHODS: A new bioartificial shoulder joint mimetic implant (S-JIM) was used to investigate the effect of vancomycin powder on C acnes growth within the first 48 hours after surgery. The impact of vancomycin was assessed on a skin-derived (ATCC 11827) C acnes strain and a periprosthetic joint infection-derived strain. C acnes strains were applied to titanium alloy foil and embedded beneath multiple layers of collagen-impregnated cellulose scaffold strips containing human shoulder joint capsular fibroblasts, facilitating the development of an oxygen gradient with an anaerobic environment around the foil and inner layers. Ten milligrams of vancomycin powder was applied between the C acnes layer and the human cell-containing scaffold strips to model direct antibiotic application, and intravenous vancomycin prophylaxis was modeled by adding vancomycin in media at 5 or 20 µg/mL. After 48 hours, the C acnes inoculum layer was subcultured from each S-JIM onto agar plates to assess the formation of viable C acnes colonies. Primary human shoulder capsule cells were assessed microscopically to detect any detrimental effects of vancomycin on cellular integrity. RESULTS: Agar plates inoculated with extracts from untreated S-JIMs consistently resulted in the growth of large numbers of C acnes colonies, whereas treatments with vancomycin powder or vancomycin in media at 20-µg/mL dilution effectively prevented the recovery of any C acnes colonies. The lowest vancomycin dilution tested (5 µg/mL) was insufficient to prevent the recovery of C acnes colonies. Vancomycin powder had no discernible short-term impact on shoulder capsule cell morphology, and the presence of these cells had no discernible impact on vancomycin degradation over time. CONCLUSIONS: Vancomycin administration effectively prevented C acnes growth in a bioartificial S-JIM. These results support the hypothesis that intra-incisional vancomycin application may limit C acnes prosthetic joint infections.

Automated Nerve Monitoring in Shoulder Arthroplasty: A Prospective Randomized Controlled Study.

BACKGROUND: Evoked potential monitoring is believed to prevent neurologic injury in various surgical settings; however, its clinical effect has not been scrutinized. It was hypothesized that an automated nerve monitor can minimize intraoperative nerve injury and thereby improve clinical outcomes in patients undergoing shoulder arthroplasty. METHODS: A prospective, blinded, parallel group, superiority design, single-center, randomized controlled study was conducted. Study participants were equally randomized into either the automated nerve-monitored or the blinded monitored groups. The primary outcome was intraoperative nerve injury burden as assessed by the cumulative duration of nerve alerts. Secondary outcomes were neurologic deficits and functional scores of the operative arm, and the quality of life index (Euro Quality of life-5 domain-5 level score) at postoperative weeks 2, 6, and 12. RESULTS: From September 2018 to July 2019, 213 patients were screened, of whom 200 were randomized. There was no statistically significant difference in the duration of nerve alerts between the automated nerve-monitored and control groups (median [25th, 75th interquartile range]: 1 [0, 18] and 5 [0, 26.5]; Hodges-Lehman difference [95% CI]: 0 [0 to 1] min; P = 0.526). There were no statistically significant differences in secondary outcomes between groups. However, in the ancillary analysis, there were reductions in neurologic deficits and improvements in quality of life index occurring in both groups over the course of the study period. CONCLUSIONS: Protection from nerve injury is a shared responsibility between surgeons and anesthesiologists. Although a progressive improvement of clinical outcomes were observed over the course of the study in both groups as a consequence of the real-time feedback provided by the automated nerve monitor, this trial did not demonstrate that automated nerve monitoring by itself changes important clinical outcomes compared with no monitoring.

Fracture profiles of a 4-year cohort of 266,324 first incident upper extremity fractures from population health data in Ontario.

BACKGROUND: Understanding the profiles of different upper extremity fractures, particularly those presenting as a 1st incident can inform prevention and management strategies. The purpose of this population-level study was to describe first incident fractures of the upper extremity in terms of fracture characteristics and demographics. METHODS: Cases with a first adult upper extremity (UE) fracture from the years 2013 to 2017 were extracted from administrative data in Ontario. Fracture locations (ICD-10 codes) and associated characteristics (open/closed, associated hospitalization within 1-day, associated nerve, or tendon injury) were described by fracture type, age category and sex. Standardized mean differences of at least 10% (clinical significance) and statistical significance (p < 0.01) in ANOVA were used to identify group differences (age/sex). RESULTS: We identified 266,324 first incident UE fractures occurring over 4 years. The most commonly affected regions were the hand (93 K), wrist/forearm(80 K), shoulder (48 K) or elbow (35 K). The highest number of specific fractures were: distal radius (DRF, 47.4 K), metacarpal (30.4 K), phalangeal (29.9 K), distal phalangeal (24.4 K), proximal humerus (PHF, 21.7 K), clavicle (15.1 K), radial head (13.9 K), and scaphoid fractures (13.2 K). The most prevalent multiple fractures included: multiple radius and ulna fractures (11.8 K), fractures occurring in multiple regions of the upper extremity (8.7 K), or multiple regions in the forearm (8.4 K). Tendon (0.6% overall; 8.2% in multiple finger fractures) or nerve injuries were rarely reported (0.3% overall, 1.5% in distal humerus). Fractures were reported as being open in 4.7% of cases, most commonly for distal phalanx (23%). A similar proportion of females (51.5%) and males were present in this fracture cohort, but there were highly variant age-sex profiles across fracture subtypes. Fractures most common in 18-40-year-old males included metacarpal and finger fractures. Fractures common in older females were: DRF, PHF and radial head, which exhibited a dramatic increase in the over-50 age group. CONCLUSIONS: UE fracture profiles vary widely by fracture type. Fracture specific prevention and management should consider fracture profiles that are highly variable according to age and sex.

Results of Linked Convertible Total Elbow Arthroplasty for the Management of Distal Humeral Fractures in the Elderly.

PURPOSE: Total elbow arthroplasty (TEA) is increasingly used for the management of comminuted distal humeral fractures in elderly patients. There are limited data on the outcome of modern elbow arthroplasty designs in larger patient cohorts. The aim of the current study was to review the outcomes and complications using a cemented convertible TEA system in a linked configuration in patients with distal humeral fractures. METHODS: Patients with distal humeral fractures treated with TEA and a minimum of 2 years' follow-up were reviewed. Demographic information, patient-reported outcome, functional and radiographic outcome assessments, and complications were reported. RESULTS: Forty patients met inclusion criteria; 35 were female. Median follow-up was 4 years (range, 2-13 years). Average age of patients at the index procedure was 79 ± 9 years. All implants were linked. Range of motion was: extension 16° ± 13°, flexion 127° ± 14°, supination 79° ± 11°, and pronation 73° ± 20°. Patient-reported outcome scores were: Patient-Rated Elbow Evaluation 37 ± 35, Quick-Disabilities of the Arm, Shoulder, and Hand 31 ± 31, and Mayo Elbow Performance Index 90 ± 18. Seven patients had heterotopic ossification. Lucent lines were noted predominantly in humeral implant zone V. No lucent lines were noted around the ulnar component in any radiographic zone. Complications occurred in 9 patients (22%) and 2 revisions were performed: one for infection and one for a late periprosthetic fracture. CONCLUSIONS: Total elbow arthroplasty for fracture in elderly patients provides pain relief, functional range of motion, and good patient-reported outcome scores. No implant-related complications of this convertible implant system were encountered, but longer-term follow-up is needed. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

The Unsalvageable Radial Head in Patients Aged 30 Years and Younger.

PURPOSE: Concern exists regarding the use of radial head arthroplasty (RHA) in younger patients. This study assessed clinical, functional, and radiographic outcomes of RHA in patients aged 30 years and younger. METHODS: A retrospective review identified 26 elbows that underwent a smooth stem modular RHA in patients aged 30 years and younger at a median follow-up of 3.3 years clinically and 2.9 years radiographically. The mean age was 24 ± 5 years. Indications were acute trauma in 13 patients and chronic pathologies in the remaining 13, and these 2 groups were evaluated separately. Patients underwent clinical, functional, and radiographic evaluation. RESULTS: Average arc of motion was 137° ± 16° in the cohort with acute trauma and 120° ± 24° in the cohort with chronic pathologies. Mean Patient-Rated Elbow Evaluation scores were 23 ± 18 (acute) and 31 ± 19 (chronic). Mean Quick Disabilities of the Arm, Shoulder, and Hand scores were 18 ± 15 (acute) and 23 ± 20 (chronic). Average Mayo Elbow Performance Index scores were 90 ± 9 (acute) and 80 ± 13 (chronic). Severe capitellar erosion was present in 1 patient (4%) in the cohort with chronic pathologies. Radiographic stem lucency was seen in all cases with 10 of these (38%) graded as severe. Moderate-to-severe ulnohumeral arthritis developed in 4 patients (15%), 3 of whom were in the chronic reconstruction group. Two patients (8%) required reoperation, 1 for persistent instability and 1 for stiffness, both in the cohort with chronic pathologies. CONCLUSIONS: For acute trauma and challenging chronic conditions involving the radial head in patients aged 30 years and younger, a smooth stem modular RHA is an option. Although reoperation rates based on this series are low, osteoarthritis is common when used for posttraumatic conditions and severe radiographic stem lucency was seen in greater than one-third of patients. These concerning features warrant close follow-up, and further long-term outcomes are needed. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Effectiveness of radiographs and computed tomography in evaluating primary elbow osteoarthritis.

BACKGROUND: Preoperative radiographic assessment of osteophyte and loose body locations is critical in planning an arthroscopic débridement for primary elbow osteoarthritis. The purpose of this study was to evaluate the effectiveness of radiographs and computed tomography (CT) in localizing osteophytes and loose bodies. METHODS: A consecutive series of 36 patients with primary elbow osteoarthritis was investigated with radiographs and multiaxial 2-dimensional CT prior to elbow arthroscopy. The location of osteophytes and loose bodies was assessed in 9 anatomic locations by 2 fellowship-trained upper extremity surgeons. The diagnostic effectiveness of both imaging modalities was evaluated by calculating the sensitivity and specificity and compared to the gold standard of elbow arthroscopy. Inter- and intrarater percentage agreement between the observations was calculated using Kappa score. RESULTS: The mean sensitivity for detecting osteophytes in the 9 different anatomic locations was 46% with radiographs and 98% with CT, whereas the mean specificity was 66% and 21% for radiographs and CT, respectively. The mean sensitivity and specificity for loose body detection with radiography were 49% and 89%, respectively, whereas CT had a mean sensitivity of 98% and specificity of 47%. The overall inter-rater percentage agreement between the surgeons in detecting osteophytes and loose bodies on radiographs was 80% and 85%, respectively, whereas on CT it was 95% for detecting osteophytes and 91% for loose bodies. CONCLUSION: CT has greater sensitivity than radiographs for the detection of osteophytes and loose bodies in primary elbow osteoarthritis. The lower specificity of CT may be due to this imaging modality's ability to detect small osteophytes and loose bodies that may not be readily identified during elbow arthroscopy. Radiographs have an inferior inter-rater percentage agreement compared with CT. CT is a valuable preoperative investigation to assist surgeons in identifying the location of osteophytes and loose bodies in patients undergoing surgery for primary elbow osteoarthritis.

The role of biceps loading and muscle activation on radial head stability in anterior Monteggia injuries: An in vitro biomechanical study.

INTRODUCTION: Little evidence-based information is available to direct the optimal rehabilitation of patients with anterior Monteggia injuries. PURPOSE OF THE STUDY: The aims of this biomechanical investigation were to (1) quantify the effect of biceps loading and (2) to compare the effect of simulated active and passive elbow flexion on radial head stability in anterior Monteggia injuries. STUDY DESIGN: In vitro biomechanical study. METHODS: Six cadaveric arms were mounted in an elbow motion simulator. The effect of biceps loading, simulated active and passive elbow flexion motions was examined with application of 0N, 20N, 40N, 60N, 80N, and 100N of load. Simulated active and passive elbow flexion motions were then performed with the forearm supinated. Radial head translation relative to the capitellum was measured using an optical tracking system. After testing the intact elbows, the proximal ulna was osteotomized and realigned using a custom jig to simulate an anatomical reduction. We then sequentially sectioned the anterior radiocapitellar joint capsule, annular ligament, quadrate ligament, and the proximal and middle interosseous membrane to simulate soft tissue injuries commonly associated with anterior Monteggia fractures. RESULTS: Greater magnitudes of biceps loading significantly increased anterior radial head translation. However, there was no significant difference in radial head translation between simulated active and passive elbow flexion except in the final stage of soft tissue sectioning. There was a significant increase in anterior radial head translation with progressive injury states with both isometric biceps loading and simulated active and passive motion. CONCLUSIONS: Our results demonstrate that anatomic reduction of the ulna may not be sufficient to restore radial head alignment in anterior Monteggia injuries with a greater magnitude of soft tissue injury. In cases with significant soft tissue injury, the elbow should be immobilized in a flexed and supinated position to allow relaxation of the biceps and avoid movement of the elbow in the early postoperative period.

Reproducibility: reliability and agreement parameters of the Revised Short McGill Pain Questionnaire Version-2 for use in patients with musculoskeletal shoulder pain.

BACKGROUND: The Revised Short McGill Pain Questionnaire Version-2 (SF-MPQ-2) is a multidimensional outcome measure designed to capture, evaluate and discriminate pain from neuropathic and non-neuropathic sources. A recent systematic review found insufficient psychometric data with respect to musculoskeletal (MSK) health conditions. This study aimed to describe the reproducibility (test-retest reliability and agreement) and internal consistency of the SF-MPQ-2 for use among patients with musculoskeletal shoulder pain. METHODS: Eligible patients with shoulder pain from MSK sources completed the SF-MPQ-2: at baseline (n = 195), and a subset did so again after 3-7 days (n = 48), if their response to the Global Rating of Change (GROC) scale remained unchanged. Cronbach alpha (α) and intraclass correlation coefficient (ICC2,1), and their related 95% CI were calculated. Standard error of measurement (SEM), group and individual minimal detectable change (MDC90), and Bland-Altman (BA) plots were used to assess agreement. RESULTS: Cronbach α ranged from 0.83 to 0.95 suggesting very satisfactory internal consistency across the SF-MPQ-2 domains. Excellent ICC2,1 scores were found in support of the total scale (0.95) and continuous subscale (0.92) scores; the remaining subscales displayed good ICC2,1 scores (0.78-0.88). Bland-Altman analysis revealed no systematic bias between the test and retest scores (mean difference = 0.13-0.19). While the best agreement coefficients were seen on the total scale (SEM = 0.5; MDC90individual = 1.2 and MDC90group = 0.3), they were acceptable for the SF-MPQ-2 subscales (SEM: range 0.7-1; MDC90individual: range 1.7-2.3; MDC90group: range 0.4-0.5). CONCLUSION: Good reproducibility supports the SF-MPQ-2 domains for augmented or independent use in MSK-related shoulder pain assessment, with the total scale displaying the best reproducibility coefficients. Additional research on the validity and responsiveness of the SF-MPQ-2 is still required in this population.

Interpretation and content validity of the items of the numeric rating version short-WORC to evaluate outcomes in management of rotator cuff pathology: a cognitive interview approach.

BACKGROUND: The shortened version of the Western Ontario Rotator Cuff Index (Short-WORC) is a patient reported outcome measure that evaluates quality of life (QoL) of patients with rotator cuff pathology. However, formal content validation of the full or Short-WORC has not been reported. This study aims to understand how 1) people interpret and calibrate responses to items on the Short-WORC and 2) compensatory strategies that might enhance function and thereby affect responses. METHODS: This study uses cognitive interviewing, a qualitative methodology that focuses on the interpretation of questionnaire items. Patients with rotator cuff disorders (n = 10), clinicians (n = 6) and measurement researchers (n = 10) were interviewed using a talk aloud structured interview that evaluated each of the 7 items of the Short-WORC. All interviews were recorded and transcribed verbatim by one researcher (R.F). Analysis was done through an open coding scheme using a previously established framework. RESULTS: Overall, the items on the Short-WORC were well received by participants. Through the interviews, the 6 themes of: Comprehension, Inadequate response definition, Reference Point, Relevance, Perspective Modifiers and Calibration Across Items emerged. The items of working above the shoulder (90%), compensating with the unaffected arm (88%) and lifting heavy objects (92%) were the most relevant to participants. Participants calibrated their scores on the items of sleeping and styling (19%) the most. Perspective modifiers of gender, influenced the calibrations of items of styling your hair (30%) and dressing or undressing (19%). Compensatory strategies of task-re allocation and using assistive devices/resources were frequently mentioned by participants. Overall, participants had minor comprehension issues, but found the 7- items of the Short-WORC to be relevant to QoL. CONCLUSIONS: Therefore, the findings demonstrate that the Short-WORC is not cognitively complex, but varies with patient perspectives. Overall, the Short-WORC provides evidence of demonstrating strong content validity when used for rotator cuff disorder patients.

Cross-cultural adaptions and measurement properties of the WORC (Western Ontario rotator cuff index): a systematic review.

BACKGROUND: To evaluate the translations, cross-cultural adaptation procedures and measurement properties of the Western Ontario Rotator Cuff Index (WORC), when it is adapted for different cultures. METHODS: A systematic review was performed, considering different cultural adaptions of the WORC accessible through MEDLINE, CINAHL, EMBASE and/or Google Scholar. Included were prospective cohort studies that used an adapted version of the WORC to measure QoL in patients with rotator cuff disorders. All studies were evaluated according to the current guidelines for cross-cultural adaptations and measurement properties. RESULTS: The search retrieved 14 studies that met the inclusion criteria. According to the recommended guidelines for cross-cultural adaptations, 8 studies performed 100% of the steps, 2 studies performed 80% of the steps and 4 studies used previously translated measures. When evaluating the studies' psychometric properties based on the quality criteria, none of the studies reported all recommended measurement properties. All of the studies reported the measurement property of reliability, but none of the studies reported agreement. Internal consistency was fully reported by 15% of studies. Construct validity was reported by 43% of studies. Only one study reported 100% of the cross-cultural adaption guidelines and 83% of the quality criteria. CONCLUSIONS: Although the majority of studies demonstrated proper adaptation procedures, testing of the measurement properties were inadequate. It is recommended that the current adapted versions of the WORC undergo further testing before use in clinical practise, and researchers continue to adapt the WORC for different cultures as it proves to be an appropriate instrument for assessing rotator cuff pathology.

In vivo volumetric and linear wear measurement of reverse shoulder arthroplasty at minimum 5-year follow-up.

BACKGROUND: Reverse shoulder arthroplasty is quickly becoming the most frequently performed glenohumeral joint replacement. The purpose of this study was to evaluate the volumetric and linear wear rates of ultrahigh-molecular-weight polyethylene humeral liners in vivo at a minimum 5-year follow-up. METHODS: Radiostereometric analysis was used to image 15 patients at terminal range of motion in forward flexion, abduction, external rotation, and internal rotation and with the arm at the side. The relative position and orientation of the glenosphere and polyethylene were identified for each arm position. The apparent intersection of the glenosphere into the polyethylene was recorded as wear. Mean volumetric and linear wear rates were recorded, and Pearson correlation coefficients were applied to the 36-mm liners to assess the relationship between the wear rate and term of service. RESULTS: The mean reverse shoulder arthroplasty term of service at the time of imaging was 8 ± 1 years (range, 6-11 years). The mean volumetric and linear wear rates for the 36-mm liners (n = 13) were 42 ± 22 mm3/yr (r = 0.688, P = .009) and 0.11 ± 0.03 mm/yr (r = 0.767, P = .002), respectively. The mean volumetric and linear wear rates for the 42-mm liners (n = 2) were 114 ± 44 mm3/yr and 0.17 ± 0.01 mm/yr, respectively. No single arm position was able to capture all recorded wear individually. CONCLUSION: This study showed volumetric and linear wear rates of approximately 40 mm3/yr and 0.1 mm/yr, respectively, for the 36-mm polyethylene liners. The 42-mm liners showed higher wear rates, although a greater number of subjects is required for conclusive results. In vivo wear of reverse total shoulder arthroplasty is multidirectional and perceptible.

The effect of short-stem humeral component sizing on humeral bone stress.

BACKGROUND: Several humeral stem design modifications for shoulder arthroplasty, including reduced stem length, changes to metaphyseal geometry, and alterations to implant surface texture, have been introduced to reduce stress shielding. However, the effect of changes in the diametral size of short-stem humeral components remains poorly understood. The purpose of this finite element study was to quantify the effect of varying the size of short-stem humeral components on the changes in bone stress from the intact state to the reconstructed state. METHODS: Three-dimensional models of 8 male cadaveric humeri (mean age, 68 ± 6 years; all left-sided humeri) were constructed from computed tomography data using Mimics software. Each humerus was then reconstructed with 2 short-stem components (Exactech Preserve), one having a larger diametral size (SH+) and one having a smaller diametral size (SH-). Modeling was conducted for loading states consistent with 45° and 75° of abduction, and the resulting changes in bone stress compared with the intact state and the expected bone response were determined. RESULTS: The smaller (SH-) short-stem implant produced humeral cortical and trabecular bone stresses that were closer to the intact state than the larger (SH+) short-stem implant at several locations beneath the humeral head resection (P ≤ .032). A similar trend was observed for expected bone response, where the smaller (SH-) short-stem implant had a smaller proportion of bone that was expected to resorb following reconstruction compared with the larger (SH+) short-stem implant for several slice depths in the medial quadrant (P ≤ .02). DISCUSSION: These findings may indicate that smaller short-stem components are favorable in terms of stress shielding.

Effect of ulnar angulation and soft tissue sectioning on radial head stability in anterior Monteggia injuries: an in vitro biomechanical study.

BACKGROUND: Radial head instability continues to be a challenge in the management of anterior Monteggia injuries; however, there is a paucity of literature on the factors that contribute to this instability. The aim of this biomechanical investigation was to examine the effects of ulnar angulation and soft tissue insufficiency on radial head stability in anterior Monteggia injuries. METHODS: Six cadaveric arms were mounted in an elbow motion simulator. Radial head translation was measured during simulated active elbow flexion with the forearm supinated. After testing the elbows in the intact state, the ulna was osteotomized and tested at 0°, 10°, 20°, and 30° of extension angulation. To examine the effect of soft tissue insufficiency, the anterior radiocapitellar joint capsule, annular ligament, quadrate ligament, and the proximal and middle interosseous membrane (IOM) were sequentially sectioned. RESULTS: There was a significant increase in anterior radial head translation with greater ulnar extension angulation. Sequential soft tissue sectioning also significantly increased anterior radial head translation. There was no increase in radial head translation with isolated sectioning of the anterior radiocapitellar joint capsule. Additional sectioning of the annular ligament and quadrate ligament slightly increased anterior radial head translation but did not reach statistical significance. Subsequent sectioning of the proximal and middle IOM resulted in significant increases in anterior radial head translation. CONCLUSION: Our study demonstrates that progressive ulnar extension angulation results in an incremental increase in anterior radial head translation in anterior Monteggia injuries. Moreover, increasing magnitudes of soft tissue disruption result in greater anterior radial head instability.

The Capitate-to-Axis-of-Radius Distance (CARD): A New Radiographic Measurement for Wrist and Carpal Alignment in the Sagittal Plane.

PURPOSE: To determine the reliability of a new radiographic index evaluating sagittal radiocarpal alignment, the capitate-to-axis-of-radius distance (CARD). A secondary purpose was to validate this index by comparing values between normal wrists and those with distal radial fractures (DRFs) and rheumatoid arthritis (RA). METHODS: The CARD is defined as the perpendicular distance from the center of the capitate head to the axis of the radius. Inter- and intraobserver reliability was tested. Cronbach alpha was calculated, and 2 methods of measurement were compared. The superior one (volar border of radial shaft) was used in the second part of the study. The normal CARD was then compared with unilateral DRFs with dorsal displacement DRF (n = 25) and RA (n = 25). Correlations between the CARD and other radiographic parameters (dorsal angulation, radial inclination, and ulnar variance) were calculated as well as between the CARD and the severity of disease or fracture displacement (mild/moderate/severe). RESULTS: The CARD showed excellent intra- and interobserver reliability. The volar radius measurement method was superior to the midaxis method and was, therefore, used for the second portion of the study. The mean CARD for normal, fractured, and RA wrists was significantly different (2.2 ± 2.5 mm, 15.7 ± 6.5 mm and 0.2 ± 4.4 mm, respectively). There was a strong side-to-side correlation in normal wrists (r = 0.77) and a significant correlation between the CARD (mm) and the severity of deformity (RA, r = -0.7; DRF, r = 0.8). CONCLUSION: The CARD is a reproducible, easy-to-use measurement of sagittal carpal alignment with a strong side-to-side correlation. The CARD increases with dorsal angulation of the distal radius and decreases as severity of deformity with RA increases. CLINICAL RELEVANCE: The correlation of the CARD with severity of deformity in DRFs and RA makes it a useful method of assessing deformities in the sagittal plane. The normal wrist can be used as a comparison when evaluating the CARD in the setting of unilateral wrist disease.