Balancing clinician and patient priorities for total shoulder replacement preoperative education programs.

OBJECTIVE: To investigate patient and clinician preferences regarding a preoperative educational program for patients undergoing shoulder replacement surgery. METHODS: This study used a cross-sectional survey of patients awaiting shoulder replacement surgery and clinicians. The survey was comprised of 41 questions for patients and clinicians, regarding preferences for receiving information, content preferences and device preferences. Descriptive statistics were reported for survey questions. RESULTS: 180 patients and 175 clinicians completed the survey. Patients and clinicians' top choices for ways to receive information were: in-person, website and booklets, with use of CD/DVD being extremely unlikely. Patients and clinicians had different preferences regarding content choices. Patients rated the following content topics as important to include in a program: including other patient's previous experiences with this surgery (83 % patients; 40 % clinicians), information for caregivers (84 % patients; 65 % clinicians), expectations for hospital stay (89 % patients; 57 % clinicians), process of anesthesia (87 % patients; 51 % clinicians), and how the surgery is performed (94 % patients; 60 % clinicians). CONCLUSIONS: Clinicians and patients have differing priorities and perspectives on the content and delivery of preoperative education programs, however, therapeutic goals and accessibility should be considered when designing programs. PRACTICE IMPLICATIONS: Creating education programs should include the lens of both clinicians and patients.

Prevalence of Symptoms of Depression, Anxiety, and Posttraumatic Stress Disorder in Workers With Upper Extremity Complaints.

Study Design Cross-sectional cohort study. Background Symptoms of depression, panic disorder (PD), and posttraumatic stress disorder (PTSD) have been associated with musculoskeletal complaints and could represent barriers to recovery in injured workers. Objectives To determine the prevalence of symptoms of depression, PD, and PTSD utilizing the Patient Health Questionnaire (PHQ) in a cohort of patients presenting to an upper extremity injured-worker clinic; secondarily, to identify any relationships between patients screening positive and patient-reported outcome measures. Methods In 2010, 418 patients completed the PHQ during their initial evaluation. Patients with PHQ scores exceeding threshold values for symptoms of depression, PD, or PTSD were compared based on patient-reported outcome scores, including the Disabilities of the Arm, Shoulder and Hand questionnaire (DASH) and Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36). The prevalence of symptoms, and their relationship with presenting complaints and patient-reported outcomes, were calculated. Results Thirty-one percent of patients scored above thresholds for symptoms of at least 1 mental health disorder. Of those who screened positive, 67% screened positive for depression, 44% for PTSD, and 50% for PD, with 43% of patients positive for multiple symptoms. Patients experiencing neck pain had significantly higher screening rates of depressive symptoms (62.5% versus 20.1%, P = .004) and PD (37.5% versus 12.9%, P = .044) compared with other presenting complaints. Similarly, patients with chronic pain had higher rates of depression (54.5% versus 20.1%, P = .006), PD (63.6% versus 12%, P<.001), and PTSD (36.4% versus 14.8%, P = .05) compared with other presenting complaints. Patients endorsing depressive symptoms had significantly lower SF-36 mental component summary scores (26.3 ± 10.7 versus 37.6 ± 9.9, P<.001) and higher shortened-version DASH (72.3 ± 16.7 versus 61.5 ± 11.1, P = .003) and DASH work scores (86.5 ± 19.2 versus 82.1 ± 20.1, P = .007) compared to patients endorsing other items on the PHQ. Conclusion In this prospective cohort study of injured workers, we identified a relatively high prevalence of symptoms of psychological disorders utilizing the PHQ, with one third of injured workers screening positive for symptoms of depression, PD, or PTSD. Further longitudinal follow-up is necessary to determine the impact on treatment outcomes. Level of Evidence Symptom prevalence, level 1b. J Orthop Sports Phys Ther 2016;46(7):590-595. Epub 12 May 2016. doi:10.2519/jospt.2016.6265.

Radial Head Fractures Treated with Modular Metallic Radial Head Replacement: Outcomes at a Mean Follow-up of Eight Years.

BACKGROUND: Radial head arthroplasty is commonly used to treat acute unreconstructible radial head fractures. The purpose of this study was to report on the clinical and radiographic outcomes at a minimum follow-up of five years after radial head arthroplasty with a modular metallic implant for the treatment of acute radial head fractures. METHODS: The cases of fifty-five patients with unreconstructible radial head fractures treated acutely with a smooth-stemmed modular metallic radial head implant were retrospectively reviewed. A wide variety of injuries, which ranged from isolated radial head fractures to so-called terrible triad injuries, were included. All patients returned for an interview, physical examination, and radiographic evaluation at a mean of eight years (range, five to fourteen years) postoperatively. Elbow and forearm motion, elbow strength, and grip strength were measured. Radiographs were evaluated, and validated patient-rated outcome questionnaires were completed. A longitudinal subgroup analysis was performed for thirty-three patients who were previously evaluated at two years postoperatively. RESULTS: At a mean of 8.2 ± 2.9 years, the mean arc of flexion (and standard deviation) of the affected elbow was 11° ± 14° to 137° ± 15°. Elbow strength and motion were significantly diminished compared with the unaffected elbow (p < 0.05). The mean Mayo Elbow Performance Index (MEPI) was 91 ± 13 points. Twenty-five patients (45%) had stem lucencies; twenty-one (38%), ulnohumeral arthritis; and twenty (36%), heterotopic ossification, including one with radioulnar synostosis. Two patients underwent secondary elbow surgery, but no patient required implant removal or revision. In the subgroup evaluated longitudinally, there was a significant improvement in MEPI scores from the two-year to the eight-year follow-up (p = 0.012), with no loss of motion or strength (p > 0.05). CONCLUSIONS: The mid-term outcomes of radial head arthroplasty with a smooth-stemmed modular metallic prosthesis are comparable with previously reported short-term outcomes, with no evidence of functional deterioration. Radial head arthroplasty with a smooth-stemmed metallic modular implant is a good treatment option for patients with acute unreconstructible radial head fractures, and sustained clinical outcomes may be expected beyond five years of follow-up. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Outcomes After Hemiarthroplasty for Proximal Humerus Fracture Are Significantly Affected by Hand Dominance.

OBJECTIVES: Hand dominance has been reported to be an important factor affecting outcomes after upper extremity trauma but remains unstudied after hemiarthroplasty for fracture. This study determined whether dominance affected outcomes after hemiarthroplasty for proximal humerus fractures. DESIGN: Retrospective cohort study. SETTING: Tertiary care referral center. PATIENTS: Sixty-one patients, after hemiarthroplasty for proximal humerus fracture, returned for comprehensive assessment and were divided into 2 groups: dominant (DOM) shoulder affected (n = 25) and non-dominant (non-DOM) shoulder affected (n = 36). INTERVENTION: Fracture-specific proximal humeral hemiarthroplasty for displaced proximal humerus fractures. MAIN OUTCOME MEASURES: Patients were assessed with self-reported outcomes (visual analog scale pain, American Shoulder and Elbow Surgeons shoulder score, disability of the arm, shoulder, and hand questionnaire, simple shoulder test, and short form 12) and objective (range-of-motion and hand-held dynamometer strength) testing. RESULTS: At 49 months of mean follow-up, there were no significant differences between groups for gender, age, follow-up time, or visual analog scale pain (P > 0.256). The DOM-affected group had significantly worse scores for American Shoulder and Elbow Surgeons shoulder score (P = 0.043), disability of the arm, shoulder, and hand questionnaire (P = 0.039), and simple shoulder test (P = 0.021). The DOM-affected group also had consistently higher correlations between self-reported and objective outcomes than the non-DOM group. CONCLUSIONS: Patients who underwent hemiarthroplasty for fracture on their DOM shoulders had significantly poorer outcomes than patients with non-DOM-sided injuries. Although positive outcomes can be expected after hemiarthroplasty, patients should be instructed that they may have less satisfactory function and strength if their injury was on the DOM side. LEVEL OF EVIDENCE: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

IGF2 expression and ß-catenin levels are increased in Frozen Shoulder Syndrome.

PURPOSE: Frozen Shoulder Syndrome is a fibrosis of the shoulder joint capsule that is clinically associated with Dupuytren's disease, a fibrosis of the palmar fascia. Little is known about any commonalities in the pathophysiology of these connective tissue fibroses. ß-catenin, a protein that transactivates gene expression, and levels of IGF2 mRNA, encoding insulin-like growth factor-II, are elevated in Dupuytren's disease. The aim of this study was to determine if correlating changes in ß-catenin levels and IGF2 expression are evident in Frozen Shoulder Syndrome. METHODS: Tissue from patients with Frozen Shoulder Syndrome and rotator cuff tear were obtained during shoulder arthroscopies. Total protein extracts were prepared from tissue aliquots and ß-catenin immunoreactivity was assessed by Western immunoblotting. In parallel, primary fibroblasts were derived from these tissues and assessed for IGF2 expression by quantitative PCR. RESULTS: ß-catenin levels were significantly increased in Frozen Shoulder Syndrome relative to rotator cuff tear when assessed by Western immunoblotting analyses. IGF2 mRNA levels were significantly increased in primary fibroblasts derived from frozen shoulder syndrome tissues relative to fibroblasts derived from rotator cuff tissues. CONCLUSIONS: As in Dupuytren's disease, ß-catenin levels and IGF2 expression are elevated in Frozen Shoulder Syndrome. These findings support the hypothesis that these connective tissue fibroses share a common pathophysiology.

Single versus double-incision technique for the repair of acute distal biceps tendon ruptures: a randomized clinical trial.

BACKGROUND: This clinical trial was done to evaluate outcomes of the single and double-incision techniques for acute distal biceps tendon repair. We hypothesized that there would be fewer complications and less short-term pain and disability in the two-incision group, with no measureable differences in outcome at a minimum of one year postoperatively. METHODS: Patients with an acute distal biceps rupture were randomized to either a single-incision repair with use of two suture anchors (n = 47) or a double-incision repair with use of transosseous drill holes (n = 44). Patients were followed at three, six, twelve, and twenty-four months postoperatively. The primary outcome was the American Shoulder and Elbow Surgeons (ASES) elbow score. Secondary outcomes included muscle strength, complication rates, and Disabilities of the Arm, Shoulder and Hand (DASH) and Patient-Rated Elbow Evaluation (PREE) scores. RESULTS: All patients were male, with no significant differences in the mean age, percentages of dominant hands affected, or Workers' Compensation cases between groups. There were also no differences in the final outcomes (at two years) between the two groups (p = 0.4 for ASES pain score, p = 0.10 for ASES function score, p = 0.3 for DASH score, and p = 0.4 for PREE score). In addition, there were no differences in isometric extension, pronation, or supination strength at more than one year. A 10% advantage in final isometric flexion strength was seen in the patients treated with the double-incision technique (104% versus 94% in the single-incision group; p = 0.01). There were no differences in the rate of strength recovery. The single-incision technique was associated with more early transient neurapraxias of the lateral antebrachial cutaneous nerve (nineteen of forty-seven versus three of forty-three in the double-incision group, p < 0.001). There were four reruptures, all of which were related to patient noncompliance or reinjury during the early postoperative period and appeared to be unrelated to the fixation technique (p = 0.3). CONCLUSIONS: There were no significant differences in outcomes between the single and double-incision distal biceps repair techniques other than a 10% advantage in final flexion strength with the latter. Most complications were minor, with a significantly greater prevalence in the single-incision group.

Surgical Technique for Single and Double-Incision Method of Acute Distal Biceps Tendon Repair.

INTRODUCTION: Distal biceps tendon ruptures can be repaired with either a single or a double-incision technique. STEP 1 SINGLE-INCISION TECHNIQUE SURGICAL EXPOSURE AND PREPARATION OF THE TENDON: Through a single anterior incision, identify the tendon and debride the distal degenerated portion. STEP 2 SINGLE-INCISION TECHNIQUE PREPARATION OF THE RADIUS: Expose the bicipital tuberosity and prepare the bone for insertion of suture anchors. STEP 3 SINGLE-INCISION TECHNIQUE TENDON REATTACHMENT: Suture the tendon with a reduction knot technique that allows for anatomic tendon apposition to bone. STEP 1 DOUBLE-INCISION TECHNIQUE SURGICAL EXPOSURE AND PREPARATION OF THE TENDON: Through a small anterior incision retrieve the tendon, debride the distal degenerated portion of the tendon, and place your sutures. STEP 2 DOUBLE-INCISION TECHNIQUE PREPARATION OF THE RADIUS: Through a second posterolateral incision, expose the biceps tuberosity and, using a burr, create a trough for the tendon. STEP 3 DOUBLE-INCISION TECHNIQUE TENDON REATTACHMENT: Pass the sutures through the transosseous tunnels and tension the sutures, allowing the biceps tendon to be pulled into the trough created in the bicipital tuberosity, and then tie the sutures. STEP 4 POSTOPERATIVE CARE: Assess tension across the repaired tendon, initiate prophylaxis against heterotopic ossification, and begin rehabilitation. RESULTS: We recently conducted a prospective randomized controlled trial at our center comparing the single and double-incision techniques for the repair of acute distal biceps tendon ruptures11. WHAT TO WATCH FOR: IndicationsContraindicationsPitfalls & Challenges.

Biomechanical analysis of fixation of middle third fractures of the clavicle.

OBJECTIVE: This biomechanical study compares four different techniques of fixation of middle third clavicular fractures. METHODS: Twenty fresh-frozen clavicles were randomized into four groups. Each group used a different fixation device (3.5 Synthes reconstruction plate, 3.5 Synthes limited contact dynamic compression plate, 3.5 Synthes locking compression plate, and 4.5 DePuy Rockwood clavicular pin). All constructs were mechanically tested in bending and torque modes both with and without a simulated inferior cortical defect. Bending load to failure was also conducted. The four groups were compared using an analysis of variance test. RESULTS: The plate constructs were stiffer than the pin during both pure bending and torque loads with or without an inferior cortical defect. Bending load to failure with an inferior cortical defect revealed that the reconstruction plate was weaker compared with the other three groups. The limited contact and locking plates were stiffer than the reconstruction plate but demonstrated statistical significance only with the cortical defect. CONCLUSIONS: As hypothesized, the 3.5 limited contact dynamic compression plate and 3.5 locking compression plate demonstrated the greatest resistance to bending and torque loads, especially in the presence of simulated comminution of a middle third clavicular fracture. The reconstruction plate demonstrated lower stiffness and strength values compared with the other plates, especially with a cortical defect, whereas the pin showed poor resistance to bending and torque loads in all modes of testing. This information may help surgeons to choose the most appropriate method of fixation when treating fractures of the middle third of the clavicle.

The simple shoulder test is responsive in assessing change following shoulder arthroplasty.

STUDY DESIGN: Prospective cohort study with repeated measures. OBJECTIVE: To establish the responsiveness of the Simple Shoulder Test (SST) in comparison to other commonly used clinical outcomes in patients undergoing shoulder arthroplasty. BACKGROUND: Responsiveness statistics are a useful means to compare different outcomes in terms of their ability to detect clinical change. While the responsiveness of the SST has been established for rotator cuff repair, it has not been determined for patients undergoing arthroplasty. METHODS: Patients undergoing shoulder arthroplasty (n=120) were evaluated prior to surgery and 6 months after. The evaluation included the SST, Disabilities of the Arm, Shoulder and Hand questionnaire, range of motion, and isometric strength. Responsiveness to change was assessed using standardized response mean (SRM), while longitudinal construct validity was evaluated using Pearson correlation. Receiver operating characteristics curves were plotted to determine clinically important difference of SST. RESULTS: The SST and Disabilities of the Arm, Shoulder and Hand questionnaire were highly responsive (SRM, >1.70) for this population. For the assessment of impairment, range of motion (SRM, 0.64-1.03) was moderately to highly responsive, while isometric strength was minimally to moderately responsive (SRM, 0.32-0.69). The clinically important difference of the SST was established at 3.0 SST points. Pearson correlations indicated moderate associations between the change scores of the SST and the Disabilities of the Arm, Shoulder and Hand questionnaire (r=0.49). CONCLUSIONS: The SST has been previously shown to be valid and highly reliable. The present results show that the SST is also responsive following shoulder arthroplasty and that it has a clinically important difference of 3.0 SST points. This should provide confidence to clinicians who wish to use a brief shoulder-specific measure in their practice.

What is a Successful Outcome Following Reverse Total Shoulder Arthroplasty?

BACKGROUND: With variations in joint destruction, patient expectations and health status, it can be difficult to interpret outcomes following arthroplasty. The purpose of this study was to determine the relationships between different outcome indicators in 44 patients followed for two years after a reverse shoulder arthroplasty. METHODS: Prospectively collected outcomes included the Constant-Murley score, Simple Shoulder Test (SST), range of motion (ROM), strength, patient satisfaction with their care and independent clinician case-review to determine global clinical outcome. Continuous outcomes were divided in two subgroups according to definitions of functional outcomes. Cohen's kappa was used to evaluate agreement between outcomes. Pearson correlations were used to quantify interrelationships. RESULTS: Although 93% of patients were substantially satisfied, fewer had good results on the other outcomes: 68% on global clinical outcome, 46% on SST and 73% on Constant-Murley score. The SST demonstrated better than chance agreement with Constant-Murley score, ROM in flexion, abduction and external rotation, and strength in external rotation. No agreement between satisfaction and other outcomes were observed. Significant correlations were observed between Constant-Murley score and SST (r = 0.78). The Constant-Murley score and SST demonstrated variable correlation with ROM and strength in flexion, abduction, internal and external rotation (0.38 < r < 0.73); the highest correlations being observed with shoulder elevation ROM (r > 0.50). CONCLUSIONS: Results show that outcome varies according to patient perspective and assessment methods. Patient satisfaction with their care was related to neither self-reported nor physical impairment outcomes. Positive patient ratings of satisfaction may not necessarily be evidence of positive outcomes.

Humeral head bone defects: remplissage, allograft, and arthroplasty.

The Hill-Sachs lesion is a well-known entity that threatens recurrent instability, but the treatment options are multiple and the surgical indications remain undefined. The evidence for each operative technique is limited to retrospective reviews and small case series without controls. The decision of which technique to use resides with the surgeon. Older, osteopenic patients, especially those with underlying arthritis and large defects, should be managed with complete humeral resurfacing. Humeralplasty is best used in younger patients with good quality bone in an acute setting with small- to moderate-sized bone defects. Partial resurfacing and remplissage are best used with small to moderate lesions, and both require further study. Allograft humeral reconstruction is an established technique for patients with moderate to large defects, and is best applied to nonosteopenic bone. Surgeons must be able to recognize the presence of humeral bone loss via specialized radiographs or cross-sectional imaging and understand its implications. The techniques to manage humeral bone loss are evolving and further biomechanical and clinical studies are required to define the indications and treatment algorithms.

Metastatic breast carcinoma of the coracoid process: two case reports.

BACKGROUND: The coracoid process of the scapula is a rare site of involvement for metastatic disease or for primary tumors. We are unaware of any reports in the literature of pathologic coracoid process fractures and only one report of metastatic disease to the coracoid. METHODS AND RESULTS: In this case report, we present two cases with metastatic breast carcinoma of the coracoid process, one of which presented with a pathologic fracture of the coracoid. CONCLUSIONS: An orthopaedic surgeon must be aware of the potential for metastatic disease to the coracoid as they may be the first medical provider to encounter evidence of malignant disease.

The incidence of early metallic suture anchor pullout after arthroscopic rotator cuff repair.

PURPOSE: The purpose of this study was to identify the incidence of metallic suture anchor pullout after arthroscopic rotator cuff repair and determine the impact of tear size on the risk of pullout. METHODS: A retrospective review of 269 patients (550 metallic suture anchors) who underwent arthroscopic rotator cuff repair between January 2006 and January 2009 was conducted. Inclusion criteria included patients aged 18 years or older, a minimum of 6 weeks' radiographic follow-up, and the use of 1 or more metallic suture anchors for partial or complete rotator cuff repair. The mean age of the cohort at the time of surgery was 55 years (range, 29 to 86 years), and there were 189 men and 80 women. RESULTS: Early anchor pullout occurred in 6 patients (9 anchors). The overall incidence of early metallic suture anchor pullout in this cohort was 2.4% (95% confidence interval, 0.5% to 4.3%). The incidence in rotator cuff tears less than or equal to 3 cm was 0.5%, and the incidence in tears greater than 3 cm was 11%. Patients undergoing arthroscopic rotator cuff repair of a tear greater than 3 cm in size were at a significantly higher risk of having early metallic suture anchor pullout than patients undergoing repair of a smaller tear (relative risk, 22; P = .001). Among the 61 patients undergoing arthroscopic subscapularis repair, no suture anchor failures were observed at the lesser tuberosity. Of the 9 anchors that failed, 8 (89%) pulled out of the posterior aspect of the greater tuberosity. CONCLUSIONS: There is a minimal risk of suture anchor pullout in small- to medium-sized tears; however, this risk increases with larger tear sizes. We recommend routine radiographic follow-up after use of metallic anchors to ensure identification of early failure by anchor pullout. LEVEL OF EVIDENCE: Level III, prognostic case series.

Improved accuracy of computer assisted glenoid implantation in total shoulder arthroplasty: an in-vitro randomized controlled trial.

BACKGROUND: Glenoid replacement is challenging due to the difficult joint exposure and visualization of anatomical reference landmarks. Improper positioning of the glenoid component or inadequate correction of the retroversion using currently available instrumentation may lead to early failure. The objective of this study was to evaluate a computer-assisted technique to achieve a more accurate placement of the glenoid component compared to traditional techniques. METHODS: Sixteen paired cadaveric shoulders were randomized to either traditional or computer-assisted glenoid implantation. Preoperative planning consisting of CT scanning with 3-dimensional image modeling of the shoulder specimens and intraoperative tracking with real-time feedback provided to the surgeon was employed in the computer-assisted group. A validated, previously published, standardized protocol for tracking the orientation of the glenoid in space using 3 glenoid surface landmarks was employed. All phases of glenoid implantation (initial guide pin insertion, reaming, drilling of the peg holes, and final component implantation) were tracked and recorded by the computer. A post-implantation CT scan was performed in both groups to compare how accurately the implants were placed. RESULTS: The computer-assisted technique was more accurate in achieving the correct version during all phases of glenoid implantation and as measured on the post-implantation CT scan (P < .05). The largest errors with traditional glenoid implantation were observed during drilling and, more so, during reaming. The trend was to overly retrovert the glenoid. CONCLUSIONS: Computer assisted navigation results in a more accurate glenoid component placement relative to traditional techniques. LEVEL OF EVIDENCE: Basic Science Study.

Open reduction and internal fixation of proximal humerus fractures.

Open reduction of proximal humeral fractures has the advantage of providing direct control over each fracture fragment and permitting anatomic reduction and fixation with advanced devices. Modern fixed-angle locking plates designed specifically for proximal humerus fractures have allowed the expansion of surgical indications permitting surgeons to address more complicated fractures. Advanced preoperative imaging and fluoroscopy allow a better understanding of fracture patterns and permit the surgeon to use this knowledge intraoperatively. Research is required to further validate fracture classification systems, to develop surgical guidelines for decision making, and to compare the outcomes of the various treatments options for proximal humerus fractures.

Humeral head translation decreases with muscle loading.

This study was conducted to determine the effect of in vitro passive and active loading on humeral head translation during glenohumeral abduction. A shoulder simulator produced unconstrained active abduction of the humerus in 8 specimens. Loading of the supraspinatus, subscapularis, infraspinatus/teres minor, and anterior, middle, and posterior deltoid muscles was simulated by use of 4 different sets of loading ratios. Significantly greater translations of the humeral head occurred both in 3 dimensions (P < .001) and in the sagittal plane (P < .005) during passive motion when compared with active motion from 30 degrees to 70 degrees of abduction. In the sagittal plane, passive abduction experienced a resultant translation of 3.8 +/- 1.0 mm whereas the active loading ratios averaged 2.3 +/- 1.0 mm. There were no significant differences in the translations that were produced by the 4 sets of muscle-loading ratios used to achieve active motions. This study emphasizes the importance of the musculature in maintaining normal ball-and-socket kinematics of the shoulder.

The effect of muscle loading on the kinematics of in vitro glenohumeral abduction.

This in vitro study evaluated the effects of four different muscle-loading ratios on active glenohumeral joint abduction. Eight cadaveric shoulders were tested using a shoulder simulator designed to reproduce unconstrained abduction of the humerus via computer-controlled pneumatic actuation. Forces were applied to cables that were sutured to tendons or fixed to bone, to simulate loading of the supraspinatus, subscapularis, infraspinatus/teres minor, and anterior, middle, and posterior deltoid muscles. Four sets of muscle-loading ratios were employed, based on: (1) equal loads, (2) average physiological cross-sectional areas (pCSAs), (3) constant values of the product of electromyographic (EMG) data and pCSAs, and (4) variable ratios of the EMG and pCSA data which changed as a function of abduction angle. The investigator generated passive motions with no muscle loads simulated. Repeatability was quantified by five successive trials of the passive and simulated active motions. There was improved repeatability in the simulated active motions versus passive motions, significant for abduction angles less than 40 degrees (p=0.02). No difference was found in the repeatability of the four different muscle-loading ratios for simulated active motions (p0.067 for all angles). The improved repeatability of active over passive motion suggests simulated active motion should be employed for in vitro simulations of shoulder motion.

An anthropometric study of the bilateral anatomy of the humerus.

The purpose of this study was to describe the extramedullary humeral morphology in paired humeri to determine whether geometric differences exist from side to side in the same individual. The anatomic characteristics of 28 paired, dry cadaveric humeri were measured by use of an electromagnetic tracking system. Of the characteristics examined, only the humeral head height was significantly different between right and left humeri in the same individual (P < .005). Most of the characteristics had excellent intra-specimen repeatability. In conclusion, there are few significant differences between contralateral humeral anatomic characteristics. Therefore, the uninjured contralateral humerus can provide a reasonable approximation to the native geometry of the fractured humerus and should be a reliable model for measuring parameters related to implant geometry and optimal positioning during hemiarthroplasty for the treatment of proximal humeral fractures.