Subscapularis structural integrity and function after arthroscopic Latarjet procedure at a minimum 2-year follow-up.

BACKGROUND: Subscapularis function after arthroscopic Bankart repair has been widely studied. However, data regarding subscapularis performance after arthroscopic Latarjet procedures are lacking. This study aimed to evaluate subscapularis clinical and radiologic performance after arthroscopic Latarjet procedures. METHODS: We included 40 patients who underwent arthroscopic Latarjet procedure with a minimum 2-year follow-up. Clinical evaluation included Western Ontario Shoulder Instability Index and Rowe scores, specific subscapularis isokinetic study, and lift-off tests. Contralateral measurements were used for comparison. Computed tomographic evaluation included graft consolidation, muscle dimensions, and degree of fatty atrophy, calculated as the mean muscle attenuation (MMA). RESULTS: There was a decrease of 8.3% of maximum internal rotation peak torque in the operated arm (P = .02). However, there was no significant difference in the agonist-antagonist ratio: 76.9% in the operated arm and 76% in the contralateral (P = .82). Lift-off strength test demonstrated a decrease in the first year but not at final follow-up (P = .38). There was a significant decrease in lift-off distance of 23% compared to the contralateral side (P < .001). Subscapularis MMA was diminished when compared to the infraspinatus/teres minor (P < .001) at the expense of its upper part (P = .03). Hyperlaxity and number of dislocation episodes were correlated to a lower MMA (P = .046 and P = .005). CONCLUSION: Arthroscopic Latarjet procedures provide satisfactory clinical results. There seems to be a diminished subscapularis MMA depending on its superior half. Hyperlaxity and number of previous dislocations were correlated to a lower MMA. Although there was a decrease in the maximum internal rotation peak torque, we did not find any difference in the agonist-antagonist ratio or in the final lift-off strength between sides.

Most coronoid fractures and fracture-dislocations with no radial head involvement can be treated nonsurgically with elbow immobilization.

HYPOTHESIS: Conservative treatment of isolated coronoid fractures and fracture-dislocations focused on soft-tissue healing can provide good clinical results in the majority of patients. Our aims were (1) to evaluate the outcome of a conservative treatment protocol designed for isolated coronoid fractures with or without associated elbow dislocations (ICFs) and (2) to characterize the fractures with a dedicated image analysis protocol. METHODS: Of 38 consecutive patients sustaining acute ICFs, 28 were treated nonsurgically after meeting specific inclusion criteria, prospectively followed up, and clinically evaluated at least 1 year after sustaining their injuries. All cases underwent elbow computed tomography scans with tri-plane and 3-dimensional reconstructions according to a specific protocol referenced to the proximal ulna. RESULTS: The study included 15 male and 13 female patients, with a mean follow-up period of 32 ± 14 months (range, 12-61 months). An associated dislocation was presented in 8 (29%). Mean extension and flexion were 2° ± 8° (range, -10° to 30°) and 139° ± 11° (range, 110°-155°), respectively. Mean pronation and supination were 74° ± 3° (range, 60°-75°) and 83° ± 9° (range, 40°-85°), respectively. Of the patients, 78% rated their elbow as being normal or nearly normal. The mean Mayo Elbow Performance Score was 95 ± 9 (range, 70-100). The mean Disabilities of the Arm, Shoulder and Hand score was 7 ± 13 (range, 0-57). The mean coronoid fracture height was 5.7 ± 1.2 mm (range, 3.7-7.9 mm). The mean percentage of coronoid height fractured was 33% ± 6% (range, 23%-43%). Mean fracture displacement was 2.7 ± 2 mm (range, 1-9 mm). Of the fractures, 23 (82%) were located at the anteromedial coronoid. CONCLUSION: An ICF with a perfectly reduced ulnohumeral joint, a competent sublime tubercle, and a fractured coronoid height up to 50% can be treated without surgery with excellent or good results in more than 90% of cases regardless of the location of the fracture in the coronoid or the type of soft tissue-associated disruptions.

Clinical outcome and prognostic factors of revision arthroscopic rotator cuff tear repair.

PURPOSE: The aim of this study was to evaluate the clinical outcome of arthroscopic rotator cuff revision surgery in a cohort of patients and to identify prognostic factors for this procedure. METHODS: Fifty-one consecutive patients undergoing revision arthroscopic rotator cuff repair were prospectively followed over a minimum period of one year. Radiologic findings and clinical data regarding primary and revision surgery were collected. Clinical evaluation was performed pre- and post-operatively by means of Constant Score and Simple Shoulder Test. RESULTS: Median age at the time of revision surgery was 60 years (range 36-77 years). Median follow-up was 25 months (range 12-58 months). There were 17 men (33.3%) and 34 women (66.7%). The majority of the tears affected the supraspinatus tendon alone (51%) or both the supra- and infraspinatus tendons (35.3%). Significant improvements were seen in terms of active forward elevation, active external rotation, pain, Simple Shoulder Test score, Constant Score, and post-operative satisfaction-age, gender, and time to revision surgery did not show significant predictive value. A smaller tear size and pre-operative elevation greater than 90° were demonstrated to be independent prognostic factors for better outcome. However, the mean increase in Constant Score was not related to the size of the tear, range of motion, or age. CONCLUSION: The results of this study indicate that arthroscopic revision rotator cuff repair results in reliable improvement in shoulder function, pain, and satisfaction. Pre-operative active range of motion and tear size seem to determine final outcome. A similar increase in mean Constant Score can be achieved even in large tears in patients aged over 65 years. LEVEL OF EVIDENCE: IV.

Clinical meaning of unexpected positive cultures (UPC) in revision shoulder arthroplasty.

PURPOSE: This study analyzed the prevalence and clinical meaning of unexpected positive cultures (UPCs) in revision shoulder arthroplasty for causes different than infection. METHODS: Between 1976 and 2007, 107 consecutive patients with UPCs, no previous suspicion of infection, and fulfilling inclusion criteria were identified. Forty-five partial (PSA) and 62 total shoulder arthroplasties (TSA) with different preoperative diagnoses were reviewed. Cases were classified as true infections, possible infections, contaminants, and undetermined. Mean follow-up was 5.6 ± 5.3 years. RESULTS: The prevalence of UPC was 15%. Male sex was a risk factor for UPC. Results of preoperative blood tests and intraoperative pathology were negative in 94 and 97 cases, respectively. Most prevalent bacteria were Propionibacterium acnes (n = 68) and Staphylococcus epidermidis (n = 21). Fifty-three patients received treatment with antibiotics and 54 did not. In 11 patients, a postoperative arthroplasty infection during follow-up was diagnosed by culture and was produced by the same microorganism as the one isolated on the UPC (true infection). Risk factors for true infection vs contamination included revision of a TSA vs a PSA and the number of previous surgeries. Antibiotic use and number of positive cultures did not influence the rate of true infections. CONCLUSIONS: UPCs are a prevalent condition in revision shoulder arthroplasty for causes different than infection. In at least 25% of cases, UPC had no clinical relevance. In 10% of cases, a persistent infection was demonstrated.

Radiographic survival in total shoulder arthroplasty.

BACKGROUND: Glenoid component loosening is thought to be a major cause of failure. This study assesses radiographic and clinical failure in shoulder arthroplasty, identifying factors predictive of loosening. METHODS: Three-hundred two shoulder arthroplasties were implanted utilizing a cemented, keeled glenoid component, mean clinical follow-up 8.6 years. One-hundred fifty one shoulders had preoperative, early postoperative, and most recent radiographs, mean radiographic follow-up 8.0 years, minimum 4 years or less if revision was performed (2 cases). RESULTS: Fifty-two of 151 glenoid components (34%) showed a shift in position or a complete lucent line ≥1.5 mm. Four humeral components (3%) shifted or showed a 2-mm lucency in 3 zones. Component survival (Kaplan-Meier) free from radiographic failure at 5 and 10 years were 99% (95% CI) (98-100%) and 67% (95% CI) (58-78%). Glenoid components with lines at the keel on initial radiographs were at risk for radiographic failure, hazard ratio 4.6 95% CI 1.2-17.2, P = .02. No associations were found between radiographic survival and age, gender, diagnosis, glenoid erosion, and preoperative or early subluxation. Late subluxation superiorly was associated with the glenoid at risk for radiographic failure (P = .006). Glenoid component survivals free from revision at 5 and 10 years for the 302 shoulders were 99% (95% CI) (97-100%) and 93% (95% CI) (90-97%). CONCLUSION: Glenoid radiolucencies are seldom seen early, except beneath the faceplate. Glenoid radiolucencies develop, with notable changes 5 or more years following surgery. Humeral components seldom loosen. Revision rates remain low. The high frequency of late radiographic changes dictates the need for innovation.

Plate Fixation of Proximal Humerus Fractures: How to Get It Right and Future Directions for Improvement.

PURPOSE OF REVIEW: Open reduction and internal fixation with locking plates (ORIF-LP) has been used for decades for the surgical management of proximal humerus fractures. Despite good outcomes have been widely published in the literature, unacceptably high rates of complications (up to 40%), many of them yielding poor outcomes and requiring reoperation (up to 25%), have also been reported, especially in elderly patients. Most common complications are related to implant failure, with intra-articular screw penetration as the most frequent and devastating. RECENT FINDINGS: Advances in patient selection and surgical technique, and implementation of bone or cement augmentation, have been developed to hopefully decrease complication rates. Mayo-FJD Classification offers prognostic information that can aid in the decision-making process for proximal humeral fractures. Displaced valgus impacted fractures seem to be associated with well over a 10% rate of avascular necrosis after ORIF-LP. A principle-based and stepwise surgical technique combining anatomic reduction and a short screw configuration can provide good outcome in most patients, even the elderly, decreasing implant failures to less than 10%. Acrylic cement augmentation has the potential to further decrease implant failure rate to 1%. Reoperation rates are higher partly due to the need to remove hardware for painful subacromial conflict. However, no studies to date definitively demonstrated the superiority of ORIF-LP compared to non-operative treatment, intramedullary nailing, or reverse shoulder arthroplasty. ORIF-LP can provide good results for the surgical management of displaced proximal humerus fractures even in elderly patients provided adequate patient selection and a principle based and stepwise surgical technique, supplemented with bone graft or acrylic cement when needed. Poor outcomes and high complication and reoperation rates should be expected when these recommendations are not followed.

Classification of proximal humerus fractures according to pattern recognition is associated with high intraobserver and interobserver agreement.

Background: The Mayo-Fundación Jiménez Díaz (FJD) classification for proximal humerus fractures aims to identify specific fracture patterns and apply displacement criteria to each pattern. The classification includes 7 common fracture patterns: isolated fractures of the greater or lesser tuberosity, fractures of the surgical neck, impacted fractures involving head rotation in a varus and posteromedial direction or in valgus, and fractures where the humeral head is dislocated (head dislocation), split (head splitting), or depressed (head impaction). The purpose of this study was to evaluate the intraobserver and interobserver agreement of the Mayo-FJD classification system using plain radiographs (xR) and computed tomography (CT). Methods: Three fellowship-trained shoulder surgeons blindly and independently evaluated the xR and CT of 103 consecutive proximal humerus fractures treated at a Level I trauma center. Each surgeon classified all fractures according to the Mayo-FJD classification system on 4 separate sessions at least 6 weeks apart. K values were calculated for intraobserver and interobserver reliability. Results: The average intraobserver agreement was 0.9 (almost perfect) for xR and 0.9 (almost perfect) for CT scans. The average interobserver agreement was 0.69 (substantial) for xR and 0.81 (almost perfect) for CT scans at the first round, and 0.66 (substantial) for xR and 0.75 (substantial) for CT scans at the second round. Conclusion: The pattern-based Mayo-FJD classification scheme for proximal humerus fractures was associated with adequate intraobserver and interobserver agreement using both xR and CT scan. Interobserver agreement was best when fractures were classified using CT scans.

Nondisplaced proximal humeral fractures: high incidence among outpatient-treated osteoporotic fractures and severe impact on upper extremity function and patient subjective health perception.

BACKGROUND: Although most proximal humeral fractures are attributed to osteoporosis, they are usually not considered individually in osteoporotic studies because of their lower incidence. The purpose of this study was to evaluate the incidence of nondisplaced proximal humeral fractures in comparison with other outpatient-treated osteoporotic fractures, as well as to assess their functional impact and effects on patient-perceived quality of life. MATERIALS AND METHODS: In this multicenter, cross-sectional, prospective study, all osteoporotic fractures in postmenopausal women aged 50 years or older treated nonoperatively in 358 trauma centers were recorded during a 3-month period. Fractures were considered osteoporotic if caused by a low-energy trauma. Pathologic fractures were excluded. The incidence of proximal humeral fractures in relation to other osteoporotic fractures was calculated. Patients were interviewed by telephone 6 months after the fracture with the Disabilities of the Arm, Shoulder and Hand and EuroQoL 5D questionnaires. RESULTS: This study comprised 5,147 women (mean age, 72.6 ± 7.5 years) with 5,268 fractures. Of these, 912 (17.5%) had had proximal humeral fractures. The mean Disabilities of the Arm, Shoulder and Hand score was 26.6 ± 25.7. Of the women, 67.3% had pain or discomfort and disclosed significant reductions in functional capacity, especially with regard to self-care (44.5%), daily life activities (56.5%), and anxiety or depression (32.7%). CONCLUSION: Nondisplaced proximal humeral fractures are among the most common fractures associated with osteoporosis, and they can be a major cause of functional disability and reduction in subjective patient-perceived health.

Revision Arthroscopic Bankart Repair Versus Arthroscopic Latarjet for Failed Primary Arthroscopic Stabilization With Subcritical Bone Loss.

BACKGROUND: Limited evidence is available regarding the recommended technique of revision surgery for recurrent shoulder instability. Only 1 previous study has compared the results of soft tissue repair and the Latarjet technique in patients with persistent shoulder instability after primary surgical stabilization. PURPOSE/HYPOTHESIS: To evaluate the results of revision surgery in patients with previous surgical stabilization failure and subcritical glenoid bone defects, comparing repeated Bankart repair versus arthroscopic Latarjet technique. The hypothesis was that Latarjet would be superior to soft tissue procedures in terms of objective and subjective functional scores, recurrence rates, and range of movement. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: Included were 45 patients (mean age, 29.1 ± 8.9 years) with subcritical bone loss (<15% of articular surface) who had undergone revision anterior shoulder instability repair after failed Bankart repair. Of these, 17 patients had arthroscopic Bankart repair and 28 had arthroscopic Latarjet surgery. Patients were evaluated at a minimum of 2 years postoperatively with the Rowe score, Western Ontario Shoulder Instability Index, and Subjective Shoulder Value. Subluxation or dislocation episodes were considered failures. RESULTS: No statistically significant differences were found between groups in age, sex, sporting activity, preoperative Rowe score, or the presence of hyperlaxity or bony lesions. At revision arthroscopy, 20 shoulders showed a persistent Bankart lesion, 13 a medially healed labrum, and 6 a bony Bankart. In 6 patients, no abnormalities were present that could explain postoperative recurrence. In the Bankart repair group, 7 patients underwent isolated Bankart procedures; in the remaining 10 cases, a capsular shift was added. No significant differences were found between the Bankart and Latarjet groups in outcome scores, recurrence rate (11.8% vs 17.9%, respectively), or postoperative athletic activity level. The mean loss of passive external rotation at 0° and 90° of abduction was similar between groups. CONCLUSION: Arthroscopic Latarjet did not lead to superior results compared with repeated Bankart repair in patients with subcritical glenoid bone loss and recurrent anterior shoulder instability after Bankart repair.

Proximal humeral fracture locking plate fixation with anatomic reduction, and a short-and-cemented-screws configuration, dramatically reduces the implant related failure rate in elderly patients.

BACKGROUND: Multiple studies have reported an unacceptable implant-related complication rate in proximal humeral fractures treated with locking plates, particularly in older patients. Our objective was to compare the fracture fixation failure rates in elderly patients, after a dedicated technique for locking plate fixation with cement augmentation or without it. METHODS: A total of 168 open reduction and internal fixation with locking plates were performed for complex proximal humerus fractures by a single surgeon in 136 women and 32 men older than 65 years of age (average 76 years). Treatment groups included group 1 with noncemented screws (n = 90) and group 2 with cemented screws (n = 78). As per Mayo-FJD Classification, there were 74 (44%) varus posteromedial impaction, 41 (24%) algus impaction, 46 (28%) surgical neck, and 7 (4%) head dislocation injuries. A retrospective radiographic and a clinical analysis was performed. RESULTS: At a mean follow-up of 33 months, the implant failure rate was significantly lower in the cement augmentation group (1% vs. 8%, P = .03). The overall complication rate was 21% (25% group 1, 15% group 2; P = .1). Global avascular necrosis was associated with sustaining a valgus impacted fracture (P = .02 odds ratio 5.7), but not to augmentation. Partial avascular necrosis occurred only in patients treated with cemented screws (3.8%). The overall revision rate was 9% in both groups. Forward elevation was 126 ± 36 degrees and external rotation was 44 ± 19 degrees. The mean Constant score was 70 ± 15 in group 1 and 76 ± 15 in group 2 (P = .03). CONCLUSION: Cement augmentation significantly decreased the rate of implant failure. Good results are expected for most patients treated with this technique.

Anteromedial approach for shoulder arthroplasty: current indications, complications, and results.

HYPOTHESIS: The anteromedial approach to the shoulder with detachment of the anterior deltoid from its clavicular and anterior acromial origins is a method of enhancing exposure for difficult shoulder arthroplasty cases. The aim of this study is to describe the current frequency of use, indications, complications, and results of this approach. MATERIALS AND METHODS: Between 2000 and 2003, 723 consecutive shoulder arthroplasties were performed. In 110 (15%) an anteromedial approach was used. Patient data; previous surgery; indications for surgery; pain, motion, and strength before and after surgery; complications; and the need for reoperation were assessed. RESULTS: This approach was used in 9.5% of primary cases and 39% of revision cases. Seventy percent had had previous surgery. For primary arthroplasty, the most frequent diagnoses were osteoarthritis and the sequelae of fractures. In revision cases the most common diagnoses were instability and glenoid loosening. The structural indications for the anteromedial approach were severe scarring, protection of a frail deltoid, improvement in rotator cuff or glenoid exposure, protection of osteopenic bone, or enhancement of exposure in oncologic cases or resections. Ninety patients had more than 2 years of follow-up. Pain improved after primary and revision arthroplasty. Motion only improved in primary arthroplasty. There was little change in strength. No proximal deltoid detachments or other approach-related complications were identified. CONCLUSIONS: The anteromedial approach is a reliable technique to improve surgical exposure in difficult shoulder arthroplasty cases. When performed adequately, it can be applied safely without anterior deltoid detachment or clinically evident major complications.

Proximal humeral fractures treated conservatively settle during fracture healing.

OBJECTIVES: Determine the relative position of the main fractured fragments of proximal humerus fractures treated conservatively to compare displacement at 2 time points: injury (0), and 1 year later (1). DESIGN: Prospective, comparative cohort study. SETTING: Level I trauma center. PATIENTS: Eighty-nine prospectively enrolled adults. INTERVENTION: Six weeks of sling immobilization and a home-based program rehabilitation protocol started 2 weeks after injury. MAIN OUTCOME MEASUREMENTS: Standardized radiographs of injured shoulders were obtained in all patients at times 0 and 1. Computed tomography scans were also obtained at these times in 73 cases. Forty-two computer-assisted measurements of displacement were performed at times 0 and 1 and then compared. Factors related to progression of displacement were analyzed. RESULTS: Ninety percent of fractures were classified into 1 of 4 patterns: posteromedial (varus) impaction (46), lateral (valgus) impaction (13), isolated greater tuberosity (15), and anteromedial impaction (6). Head-shaft displacement increased over time. In posteromedial impaction fractures, average fracture settling included 9 degrees in varus, 7 degrees in retroversion, and 3.2 mm in posterior shortening. In valgus-impacted fractures, a decrease in valgus tilt and a tendency toward a more anterior orientation of the articular surface was observed. Greater tuberosity displacement increased more than 5 mm in less than 20% of cases. Age and initial displacement were related to progression of displacement. CONCLUSIONS: Proximal humerus fractures treated conservatively settle at the head-shaft junction during healing. Substantial additional displacement of tuberosities was seldom observed. LEVEL OF EVIDENCE: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Heterotopic ossification after surgery for fractures and fracture-dislocations involving the proximal aspect of the radius or ulna.

BACKGROUND: The objectives of this study were to (1) determine the prevalence of heterotopic ossification after surgery for fractures and fracture-dislocations involving the proximal aspect of the radius or ulna, (2) identify risk factors associated with the development of heterotopic ossification in these injuries, and (3) characterize the severity and location of the heterotopic ossification and the associated range of elbow motion. METHODS: From 2004 to 2008, 142 elbow fractures and fracture-dislocations involving the proximal aspect of the radius or ulna were treated surgically at our institution. Records and radiographs of 130 elbows with adequate follow-up were retrospectively reviewed to identify cases of heterotopic ossification, characterize the ectopic bone, and analyze associated risk factors. The most frequent injuries included olecranon fractures, Monteggia fracture-dislocations, and various combinations of fractures of the radial head and coronoid with or without dislocation or subluxation. RESULTS: Heterotopic bone was identified on the radiographs of forty-eight elbows (37%). Heterotopic ossification interfered with motion in twenty-six elbows (20%), and thirteen elbows (10%) underwent additional surgery to remove heterotopic bone with the goal of improving motion. Risk factors associated with the development of heterotopic ossification included elbow subluxation or dislocation at the time of presentation, an open fracture, a severe chest injury, and a delay in definitive surgical treatment. Ectopic bone was preferentially located at the origin of torn soft-tissue structures or around fracture sites, and it was particularly common around the posterior aspect of the ulna and the neck of the radius. Heterotopic ossification was classified on radiographs as hazy immature in twenty-two elbows, limited mature in eighteen, extensive mature in five, and a complete bone bridge in three. Heterotopic ossification was more common in patients with an associated distal humeral fracture, radial head and coronoid fractures with an associated elbow dislocation (terrible triad injury), and a transolecranon fracture-dislocation. CONCLUSIONS: Thirty-seven percent of elbows treated surgically for fractures involving the proximal aspect of the radius and/or ulna developed heterotopic ossification. In twenty percent of elbows, heterotopic ossification was associated with clinically relevant motion deficits. More severe heterotopic ossification was encountered in patients presenting with an associated distal humeral fracture, terrible triad injury, transolecranon fracture-dislocation, or Monteggia fracture-dislocation. Patients with an open injury, instability, severe chest trauma, or delay in definitive surgical treatment had a higher prevalence of heterotopic ossification.

The surgical treatment of periprosthetic elbow fractures around the ulnar stem following semiconstrained total elbow arthroplasty.

BACKGROUND: Limited information exists related to the treatment of periprosthetic fractures of the ulna after semiconstrained elbow arthroplasty. Our goals were to characterize the clinical and radiographic features of periprosthetic fractures around the stem of a loose ulnar component and to determine the outcomes after surgical treatment. METHODS: Between 1980 and 2008, thirty consecutive periprosthetic fractures around the ulnar stem were treated surgically at our institution. Eighteen fractures occurred after primary arthroplasty, and twelve occurred after revision arthroplasty. The mean time between the index arthroplasty and the fracture was eight years. All ulnar components were loose. Ulnar bone loss was moderate in fourteen elbows and severe in sixteen. Surgical reconstruction included revision of the ulnar component in all cases. Fracture fixation was achieved with a longer stemmed implant only in two elbows. Strut allografts were used in twenty elbows, with additional impaction graft augmentation in eight of them. Three additional elbows were revised with impaction grafting alone, and five were reconstructed with an allograft ulnar prosthetic composite. Seven patients were lost to follow-up, one died, and one was managed with conversion to a resection arthroplasty following a deep infection. The remaining twenty-one patients were followed for a mean of 4.9 ± 2.6 years. RESULTS: At the time of the most recent follow-up, eighteen patients reported no pain or mild pain and three patients reported moderate pain. The mean arc of elbow flexion and extension was 112°. The Mayo Elbow Performance Score was 82 points (with fifteen good or excellent results and six fair or poor results). Fracture-healing was achieved in the twenty-one followed patients. Complications included three deep infections, one superficial infection, one case of ulnar component loosening, and one case of transient dysfunction of both the median and radial nerves. CONCLUSIONS: Periprosthetic ulnar fractures around the stem of a loose ulnar component after total elbow arthroplasty usually combine implant loosening and severe bone loss. Revision of the ulnar component may require additional strut allografts, allograft-prosthetic composites, or impaction grafting. Satisfactory outcomes were seen after the majority of revisions; however, deep infections and component loosening continue to be serious complications.

Proximal humerus fracture rotational stability after fixation using a locking plate or a fixed-angle locked nail: the role of implant stiffness.

BACKGROUND: Fixed-angle locked devices have been developed to improve internal fixation of proximal humerus fractures. Available low-profile precontoured locking plates and intramedullary nails with fixed-angle interlocks are currently favored by most surgeons in this setting. The aim of this study was to assess the relative stability of these two methods of fixation under torsion load. METHODS: A surgical neck osteotomy was created in six pairs of embalmed humeri. In each pair, one specimen was secured with a titanium locking-compression plate, and the contralateral was secured with a titanium nail with a proximal locked spiral blade. The specimens were first tested cyclically in internal-external rotation for 10,000 cycles to evaluate interfragmentary motion (dynamic study). At the end of the cyclic testing, the specimens were loaded to failure in external rotation to measure torque to failure and construct stiffness (static study). FINDINGS: There were no significant differences in interfragmentary motion between the two fixation devices in the dynamic study. When tested to failure, fixation with the locking plate tolerated on average 20 more degrees in torsion before failure, and demonstrated higher torsional load to failure and less torsional stiffness (P<0.05). INTERPRETATION: Both locking plates and locked intramedullary nails may provide enough stability to avoid secondary displacement of proximal humerus fractures during early physical therapy. Locking plates demonstrated superior biomechanical properties under high rotational loads than locked intramedullary nails in a cadaveric proximal humerus two-part osteotomy model, and could provide more protection against unexpected high torsion loads.