Joseph R. Lynch

Glenoid Component Failure in Total Shoulder Arthroplasty

Glenoid component failure is the most common complication of total shoulder arthroplasty. Glenoid components fail as a result of their inability to replicate essential properties of the normal glenoid articular surface to achieve durable fixation to the underlying bone, to withstand repeated eccentric loads and glenohumeral translation, and to resist wear and deformation. The possibility of glenoid component failure should be considered whenever a total shoulder arthroplasty has an unsatisfactory result. High-quality radiographs made in the plane of the scapula and in the axillary projection are usually sufficient to evaluate the status of the glenoid component. Failures of prosthetic glenoid arthroplasty can be understood in terms of failure of the component itself, failure of seating, failure of fixation, failure of the glenoid bone, and failure to effectively manage eccentric loading. An understanding of these modes of failure leads to strategies to minimize complications related to prosthetic glenoid arthroplasty.

Commercially Funded and United States-Based Research Is More Likely to Be Published; Good-Quality Studies with Negative Outcomes Are Not

BACKGROUND Prior studies implying associations between receipt of commercial funding and positive (significant and/or pro-industry) research outcomes have analyzed only published papers, which is an insufficiently robust approach for assessing publication bias. In this study, we tested the following hypotheses regarding orthopaedic manuscripts submitted for review: (1) nonscientific variables, including receipt of commercial funding, affect the likelihood that a peer-reviewed submission will conclude with a report of a positive study outcome, and (2) positive outcomes and other, nonscientific variables are associated with acceptance for publication. METHODS All manuscripts about hip or knee arthroplasty that were submitted to The Journal of Bone and Joint Surgery, American Volume, over seventeen months were evaluated to determine the study design, quality, and outcome. Analyses were carried out to identify associations between scientific factors (sample size, study quality, and level of evidence) and study outcome as well as between non-scientific factors (funding source and country of origin) and study outcome. Analyses were also performed to determine whether outcome, scientific factors, or nonscientific variables were associated with acceptance for publication. RESULTS Two hundred and nine manuscripts were reviewed. Commercial funding was not found to be associated with a positive study outcome (p = 0.668). Studies with a positive outcome were no more likely to be published than were those with a negative outcome (p = 0.410). Studies with a negative outcome were of higher quality (p = 0.003) and included larger sample sizes (p = 0.05). Commercially funded (p = 0.027) and United States-based (p = 0.020) studies were more likely to be published, even though those studies were not associated with higher quality, larger sample sizes, or lower levels of evidence (p = 0.24 to 0.79). CONCLUSIONS Commercially funded studies submitted for review were not more likely to conclude with a positive outcome than were nonfunded studies, and studies with a positive outcome were no more likely to be published than were studies with a negative outcome. These findings contradict those of most previous analyses of published (rather than submitted) research. Commercial funding and the country of origin predict publication following peer review beyond what would be expected on the basis of study quality. Studies with a negative outcome, although seemingly superior in quality, fared no better than studies with a positive outcome in the peer-review process; this may result in inflation of apparent treatment effects when the published literature is subjected to meta-analysis.

Treatment of osseous defects associated with anterior shoulder instability.

Bone loss of the glenoid and/or humerus is a common consequence of traumatic anterior shoulder instability and can be a cause of recurrent instability after a Bankart repair. Accurate characterization of the size and location of osseous defects associated with traumatic instability is important when planning treatment. Open or arthroscopic soft tissue repairs are usually sufficient when less than 25% of the width of the glenoid bone has been lost. Bone replacement techniques may be necessary when glenoid bone loss is greater than 25% of the glenoid width. Glenoid bone restoration techniques include the use of a tricortical iliac crest graft or the transfer of the coracoid process to the area of glenoid deficiency. Bone grafting becomes a strong consideration when soft tissue repairs have failed to restore stability. Treatment of these severe defects may be followed by osteoarthritis. The destabilizing effects of anterior glenoid bone defects are compounded by concurrent defects of the posterior-lateral humeral head, commonly known as Hill-Sachs lesions, which can engage the glenoid defect. Large humeral head defects can be treated by transhumeral bone grafting techniques or osteoarticular allograft reconstruction. Prosthetic replacement of the proximal humerus is considered for humeral head defects involving more than 40% of the articular surface. Understanding the importance of humeral and glenoid bone deficiencies may help guide the treatment of recurrent anterior glenohumeral instability.

Femoral nonunion: risk factors and treatment options.

Abstract Despite advances in surgical technique, fracture fixation alternatives, and adjuncts to healing, femoral nonunion continues to be a significant clinical problem. Femoral fractures may fail to unite because of the severity of the injury, damage to the surrounding soft tissues, inadequate initial fixation, and demographic characteristics of the patient, including nicotine use, advanced age, and medical comorbidities. Femoral nonunion is a functional and economical challenge for the patient, as well as a treatment dilemma for the surgeon. Surgeons should understand the various treatment alternatives and their role in achieving the goals of deformity correction, infection management, and optimization of muscle strength and rehabilitation. Used appropriately, nail dynamization, exchange nailing, and plate osteosynthesis can help minimize pain and disability by promoting osseous union. A review of the potential risk factors and treatment alternatives should provide insight into the etiology and required treatment of femoral nonunion.

Self-Assessed Outcome at Two to Four Years After Shoulder Hemiarthroplasty with Concentric Glenoid Reaming

BACKGROUND Active and young individuals with glenohumeral arthritis who are treated with total glenohumeral arthroplasty are at risk for loosening or wear of the prosthetic glenoid component. This study tests the hypothesis that patients with severe glenohumeral arthritis have improvement in self-assessed shoulder comfort and function at two to four years after treatment with the combination of humeral hemiarthroplasty and concentric glenoid reaming without tissue or prosthetic component interposition. METHODS Thirty-seven consecutive patients (thirty-eight shoulders), with a mean age of fifty-seven years, who were managed by one surgeon were enrolled in this prospective study. The procedure consisted of an uncemented humeral hemiarthroplasty combined with reaming of the glenoid to a diameter 2 mm larger than that of the prosthetic humeral head. The duration of follow-up ranged from two to four years (average, 2.7 years) for thirty-five shoulders. Self-assessed comfort and function was documented with use of the Simple Shoulder Test, and radiographs were evaluated. RESULTS Thirty-two shoulders demonstrated improved comfort and function according to patient self-assessment, one demonstrated no change, and two had worse function following the procedure. The total number of Simple Shoulder Test functions that could be performed increased from 4.7 (of a possible 12.0) before surgery to 9.4 at the time of the final follow-up. The patients demonstrated significant improvement in ten of the twelve individual functions of the Simple Shoulder Test (p < 0.022 to p < 0.00001). With the numbers studied, gender, diagnosis, age, glenoid wear, and preoperative glenoid erosion did not significantly affect final shoulder function or overall improvement. The range of motion was significantly improved for all individuals (p < 0.00001). Radiographically, twenty-two patients had a joint space between the glenoid bone and the humeral prosthesis at the time of final follow-up. These shoulders had significantly better function than those without a preserved joint space (p < 0.017). There were no surgical complications and no revisions to total shoulder arthroplasty. CONCLUSIONS At a minimum follow-up of two years, a selected series of patients who had humeral hemiarthroplasty with concentric glenoid reaming for the treatment of glenohumeral arthritis showed significant improvement in self-assessed shoulder comfort and function. Further study, however, is needed before routine application of this procedure can be recommended. LEVEL OF EVIDENCE Therapeutic Level IV.

Risk factors for femoral nonunion after femoral shaft fracture

The purpose of this study was to evaluate risk factors for nonunion after femoral nailing of femoral shaft fractures. A case-control study with two to one matching was conducted. Forty-five patients with 46 femoral nonunions (cases) and 92 patients with healed femoral shaft fractures (controls) were identified from our orthopedic trauma registry. All cases and controls were initially managed with reamed, statically locked femoral nails. The characteristics that were significantly different between the two groups were open fracture, delay to weight bearing, and tobacco use. Fracture classification, gender, direction of nail insertion (antegrade vs. retrograde), and Injury Severity Score were not predictive of nonunion. We conclude that open fracture, tobacco use, and delayed weight bearing are risk factors for femoral nonunion after intramedullary nailing for diaphyseal femur fractures.

Glenohumeral chondrolysis: A systematic review of 100 cases from the English language literature

HYPOTHESIS Chondrolysis can be a devastating complication of shoulder arthroscopy. We undertook a review of the 100 cases reported in the English language to test the hypothesis that common factors could be identified and that the identification of these factors could suggest strategies for avoiding this complication. MATERIALS AND METHODS We systematically reviewed the English language literature and identified 16 articles reporting 100 shoulders in which postsurgical glenohumeral chondrolysis had developed. RESULTS The average reported patient age was 27 +/- 11 years at the time of surgery; 35 were women. The most common indications for surgery were instability (n = 68) and superior labrum anteroposterior lesions (n = 17). In 59 cases, chondrolysis was reported to be associated with the use of intra-articular pain pumps. The infusate was known to include bupivacaine in 50 shoulders and lidocaine in 2. Radiofrequency capsulorrhaphy was performed in 2 shoulders. DISCUSSION Fifty-nine percent of the reported cases of glenohumeral chondrolysis occurred with the combination of arthroscopic surgery and postarthroscopy infusion of local anesthetic. The arthroscopic operations observed with chondrolysis were not limited to stabilization procedures, and the infused anesthetic was not limited to bupivacaine. CONCLUSION In that postoperative infusion of local anesthetic and radiofrequency may not be essential to the success of shoulder arthroscopy, surgeons may wish to consider the possible risks of their use.

Important Demographic Variables Impact the Musculoskeletal Knowledge and Confidence of Academic Primary Care Physicians

BACKGROUND Although most musculoskeletal illness is managed by primary care providers, and not by surgeons, evidence suggests that primary care physicians may receive inadequate training in musculoskeletal medicine. We evaluated the musculoskeletal knowledge and self-perceived confidence of fully trained, practicing academic primary care physicians and tested the following hypotheses: (1) a relationship exists between a providers musculoskeletal knowledge and self-perceived confidence, (2) demographic variables are associated with differences in the knowledge-confidence relationship, and (3) specific education or training affects a providers musculoskeletal knowledge and clinical confidence. METHODS An examination of basic musculoskeletal knowledge and a 10-point Likert scale assessing self-perceived confidence were administered to family practice, internal medicine, and pediatric faculty at a large, regional, academic primary care institution serving both rural and urban populations across a five-state region. Subspecialty physicians were excluded. Individual examination scores and self-reported confidence scores were correlated and compared with demographic variables. RESULTS One hundred and five physicians participated. Ninety-two physicians adequately completed the musculo-skeletal knowledge examination. Fifty-nine (64%) of the ninety-two physicians scored < 70%. Higher examination scores were associated with male gender (p = 0.01) and participation in a musculoskeletal course (p = 0.009). Practitioners who took elective courses demonstrated higher scores compared with those who took required courses (p = 0.014). Greater musculoskeletal confidence was associated with the number of years in clinical practice (p = 0.045), male gender (p = 0.01), residency training in family practice (p < 0.00001), and prior participation in a musculoskeletal course (p = 0.0004). Physicians demonstrated greater confidence with medical issues than with musculoskeletal issues (mean confidence scores, 8.3 and 5.1, respectively; p < 0.00001). Higher scores for musculoskeletal knowledge correlated significantly with increasing levels of musculoskeletal confidence (r = 0.416, p < 0.0001). CONCLUSIONS Although a large proportion of primary care visits are for musculoskeletal symptoms, the majority of primary care providers tested at a large, regional, academic primary care institution failed to demonstrate adequate musculoskeletal knowledge and confidence. Further characterization of the relationship between knowledge and confidence and its association with demographic variables might benefit the education of musculoskeletal providers in the future.

Medial Collateral Ligament Injury in the Overhand-Throwing Athlete

Medial collateral ligament injuries are rare and occur almost exclusively in overhand-throwing athletes. The late cocking phase of the overhand throw places a marked valgus moment across the medial elbow. This repetitive force reaches the tensile limits of the medial collateral ligament, subjecting it to microtraumatic injury and attenuation. The anterior bundle of the medial collateral ligament has been identified as the primary restraint to valgus load and is the focus of reconstruction. Diagnosis of medial collateral ligament injuries should be suspected in any overhand-throwing athlete with a history of medial-sided elbow pain, decreased control, and reduced throwing velocity. Injury to the medial collateral ligament can be confirmed by physical examination (moving valgus stress test) and appropriate imaging studies (computed tomography arthrogram and magnetic resonance imaging). Reconstructive techniques of the medial collateral ligament have evolved over time and currently provide superior outcomes, with 80% to 90% of athletes returning to the same level of competitive play. As our understanding of the pathoanatomy of medial elbow injuries progresses and newer hybrid techniques evolve, our ability to care for the overhand-throwing athlete can be expected to improve.

Thermal Effects of Glenoid Reaming During Shoulder Arthroplasty in Vivo

BACKGROUND Glenoid component loosening is a common cause of failure of total shoulder arthroplasty. It has been proposed that the heat generated during glenoid preparation may reach temperatures capable of producing osteonecrosis at the bone-implant interface. We hypothesized that temperatures sufficient to induce thermal necrosis can be produced with routine drilling and reaming during glenoid preparation for shoulder arthroplasty in vivo. Furthermore, we hypothesized that irrigation of the glenoid during reaming can reduce this temperature increase. METHODS Real-time, high-definition, infrared thermal video imaging was used to determine the temperatures produced by drilling and reaming during glenoid preparation in ten consecutive patients undergoing total shoulder arthroplasty. The maximum temperature and the duration of temperatures greater than the established thresholds for thermal necrosis were documented. The first five arthroplasties were performed without irrigation and were compared with the second five arthroplasties, in which continuous bulb irrigation was used during drilling and reaming. A one-dimensional finite element model was developed to estimate the depth of penetration of critical temperatures into the bone of the glenoid on the basis of recorded surface temperatures. RESULTS Our first hypothesis was supported by the recording of maximum surface temperatures above the 56°C threshold during reaming in four of the five arthroplasties done without irrigation and during drilling in two of the five arthroplasties without irrigation. The estimated depth of penetration of the critical temperature (56°C) to produce instantaneous osteonecrosis was beyond 1 mm (range, 1.97 to 5.12 mm) in four of these patients during reaming and one of these patients during drilling, and two had estimated temperatures above 56°C at 3 mm. Our second hypothesis was supported by the observation that, in the group receiving irrigation, the temperature exceeded the critical threshold in only one specimen during reaming and in two during drilling. The estimated depth of penetration for the critical temperature (56°C) did not reach a depth of 1 mm in any of these patients (range, 0.07 to 0.19 mm). CONCLUSIONS Temperatures sufficient to induce thermal necrosis of glenoid bone can be generated by glenoid preparation in shoulder arthroplasty in vivo. Frequent irrigation may be effective in preventing temperatures from reaching the threshold for bone necrosis during glenoid preparation.