Comparison of patients undergoing primary shoulder arthroplasty before and after the age of fifty

BACKGROUND

The reported outcomes of shoulder arthroplasty in patients under the age of fifty years are worse than those in patients over fifty. While there are several possible explanations for this finding, we explored the possibility that patients who had a primary shoulder arthroplasty when they were under fifty years of age differed from those who had the procedure when they were over fifty with respect to their pre-arthroplasty self-assessed comfort and function, sex distribution, and specific type of arthritis.

METHODS

The study group consisted of patients with glenohumeral arthritis who were treated with a primary shoulder arthroplasty by the same surgeon between 1990 and 2008. For each decade of age, the sex distribution, the pre-arthroplasty self-assessed shoulder comfort and function, and the prevalence of twelve different diagnoses were documented. We reviewed the series for three potential causes of worse outcomes in patients under fifty years of age as compared with those over fifty years of age: (1) a higher percentage of women, (2) a lower score for pre-arthroplasty self-assessed comfort and function, and (3) more complex pathological conditions.

RESULTS

Patients under the age of fifty years were not more likely than those over fifty to be female or to have a lower pre-arthroplasty self-assessed comfort and function score, but they did have more complex pathological conditions, such as capsulorrhaphy arthropathy, rheumatoid arthritis, and posttraumatic arthritis. Only 21% of the younger patients had primary degenerative joint disease, whereas 66% of the older patients had that diagnosis. This difference was significant (p < 0.000000001).

CONCLUSIONS

Surgeons performing shoulder arthroplasty in individuals under the age of fifty should be prepared to encounter pathological conditions such as capsulorrhaphy arthropathy, rheumatoid arthritis, and posttraumatic arthritis rather than primary osteoarthritis, which is more common in individuals older than fifty. The pathoanatomy in these younger patients may complicate the surgery, the rehabilitation, and the outcome of the shoulder arthroplasty.

Charles Neer: on the giant of the shoulder

In the world of orthopedics, certain giants have become known as associated with a single subspecialty or for work on a single joint. Among these are John Charnley, for his work on total hip arthroplasty, and Amory Codman, for his work on the shoulder. But in the second half of the 20th century, the true giant of shoulder surgery was Charles Neer. His contributions to our subspecialty may not have been surpassed by any orthopedic surgeon for any subspecialty. This article explores his life and his contributions to shoulder surgery from those who knew him best.

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.

Proximal humeral fracture as a risk factor for subsequent hip fractures

BACKGROUND

With the aging of the world's population, the social and economic implications of osteoporotic fractures are at epidemic proportions. This study was performed to test the hypothesis that a proximal humeral fracture is an independent risk factor for a subsequent hip fracture and that the risk of the subsequent hip fracture is highest within the first five years after the humeral fracture.

METHODS

A cohort of 8049 older white women with no history of a hip or humeral fracture who were enrolled in the Study of Osteoporotic Fractures was followed for a mean of 9.8 years. The risk of hip fracture after an incident humeral fracture was estimated with use of age-adjusted Cox proportional hazards regression analysis with time-varying variables; women without a humeral fracture were the reference group. Cox regression analysis was used to evaluate the timing between the proximal humeral and subsequent hip fracture. Risk factors were determined on the basis of a review of the current literature, and we chose the variables that were most predictive and easily ascertained in a clinical setting.

RESULTS

Three hundred and twenty-one women sustained a proximal humeral fracture, and forty-four of them sustained a subsequent hip fracture. After adjustment for age and bone mineral density, the hazard ratio for hip fracture for subjects with a proximal humeral fracture relative to those without a proximal humeral fracture was 1.83 (95% confidence interval = 1.32 to 2.53). After multivariate adjustment, this risk appeared attenuated but was still significant (hazard ratio = 1.57; 95% confidence interval = 1.12 to 2.19). The risk of a subsequent hip fracture after a proximal humeral fracture was highest within one year after the proximal humeral fracture, with a hazard ratio of 5.68 (95% confidence interval = 3.70 to 8.73). This association between humeral and hip fracture was not significant after the first year, with hazard ratios of 0.87 (95% confidence interval = 0.48 to 1.59) between one and five years after the humeral fracture and 0.58 (95% confidence interval = 0.22 to 1.56) after five years.

CONCLUSIONS

In this cohort of older white women, a proximal humeral fracture independently increased the risk of a subsequent hip fracture more than five times in the first year after the humeral fracture but was not associated with a significant increase in the hip fracture risk in subsequent years.

Pronation can increase the pressure on the posterior interosseous nerve under the arcade of Frohse: a possible mechanism of palsy after two-incision repair for distal biceps rupture--clinical experience and a cadaveric investigation

Posterior interosseous nerve palsy is a recognized complication of 2-incision distal biceps tendon repair. We hypothesize that intraoperative forearm pronation can cause compression of the posterior interosseous nerve beneath the supinator and arcade of Frohse. Six human male cadaver upper extremities were dissected. Pressure on the posterior interosseous nerve beneath the arcade of Frohse and supinator was measured with a Swan-Ganz catheter connected to a pressure transducer. Pressure was significantly elevated in maximal pronation in all specimens with the elbow in both flexion and extension. Pressures at full pronation were significantly higher than pressures measured at 60 degrees of pronation (5 +/- 2 mm Hg in 60 degrees of pronation and 90 degrees of flexion, P < .0001; 7 +/- 3 mm Hg in 60 degrees of pronation and extension, P < 005). Maximal pronation can cause increased pressure on the posterior interosseous nerve. The safety of 2-incision distal biceps repair may be increased by avoiding prolonged, uninterrupted periods of hyperpronation.

Fourier transform inequalities for phylogenetic trees

Phylogenetic invariants are not the only constraints on site-pattern frequency vectors for phylogenetic trees. A mutation matrix, by its definition, is the exponential of a matrix with non-negative off-diagonal entries; this positivity requirement implies non-trivial constraints on the site-pattern frequency vectors. We call these additional constraints "edge-parameter inequalities". In this paper, we first motivate the edge-parameter inequalities by considering a pathological site-pattern frequency vector corresponding to a quartet tree with a negative internal edge. This site-pattern frequency vector nevertheless satisfies all of the constraints described up to now in the literature. We next describe two complete sets of edge-parameter inequalities for the group-based models; these constraints are square-free monomial inequalities in the Fourier transformed coordinates. These inequalities, along with the phylogenetic invariants, form a complete description of the set of site-pattern frequency vectors corresponding to bona fide trees. Said in mathematical language, this paper explicitly presents two finite lists of inequalities in Fourier coordinates of the form "monomial < or = 1", each list characterizing the phylogenetically relevant semialgebraic subsets of the phylogenetic varieties.

Full-thickness rotator cuff tear prevalence and correlation with function and co-morbidities in patients sixty-five years and older

The purpose of this study was to determine full-thickness rotator cuff tear prevalence in patients 65 and older and to correlate tears with comfort, function, and co-morbidities. Two-hundred shoulders without prior surgery were evaluated with a Simple Shoulder Test, a Constant Score, and ultrasound. Full thickness tear prevalence was 22%. Adjusting for age and gender, those with tears had lower scores than those without (P < .001 for each). Adjusting for many potential confounders, with a 10-year age increase, the odds of a tear increased 2.69-fold (P = .005). For those with tears, scores were no different for those who had seen a physician for their shoulder compared to those who had not. Full-thickness cuff tear prevalence was 22% in those 65 and older. Tear prevalence increased with increasing age. Shoulder scores were poorer for those with tears.

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.

Phylogenetic mixtures on a single tree can mimic a tree of another topology

Phylogenetic mixtures model the inhomogeneous molecular evolution commonly observed in data. The performance of phylogenetic reconstruction methods where the underlying data are generated by a mixture model has stimulated considerable recent debate. Much of the controversy stems from simulations of mixture model data on a given tree topology for which reconstruction algorithms output a tree of a different topology; these findings were held up to show the shortcomings of particular tree reconstruction methods. In so doing, the underlying assumption was that mixture model data on one topology can be distinguished from data evolved on an unmixed tree of another topology given enough data and the "correct" method. Here we show that this assumption can be false. For biologists, our results imply that, for example, the combined data from two genes whose phylogenetic trees differ only in terms of branch lengths can perfectly fit a tree of a different topology.

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.

Nonprosthetic glenoid arthroplasty with humeral hemiarthroplasty and total shoulder arthroplasty yield similar self-assessed outcomes in the management of comparable patients with glenohumeral arthritis

The risk of glenoid component failure has led us to explore nonprosthetic glenoid arthroplasty coupled with humeral hemiarthroplasty, the "ream and run" (R&R) procedure, for the management of glenohumeral arthritis in active patients. We hypothesized that patients having a R&R procedure would have outcomes comparable with those of similar patients having a total shoulder arthroplasty (TSA). A case-matched control study compared 35 consecutive patients (32 men, 3 women) with an average age of 56 years, after R&R with matched controls having TSA. The respective Simple Shoulder Test (SST) scores for the R&R and TSA groups were 4.5 and 4.0 before surgery, 7.8 and 9.6 at 12 months, 8.3 and 10.2 at 18 months, 8.9 and 9.4 at 24 months, 9.4 and 9.6 at 30 months, and 9.5 and 10.0 at 36 months. The "ream and run" procedure can offer similar functional recovery to patients with total shoulder arthroplasty, although the time to recovery may be longer.

The complex characteristics of 282 unsatisfactory shoulder arthroplasties

The purpose of our study is to augment the knowledge of patient dissatisfaction after a shoulder arthroplasty. A total of 353 shoulders were prospectively enrolled into the Shoulder Arthroplasty Failure Experience (SAFE) project. Of these, 282 patients had complete data for the final analysis, including demographic information, medical history, physical examination, standard radiographs, and the Simple Shoulder Test (SST) scores. These data were analyzed to determine the frequency of 17 possible characteristics of an unsatisfactory arthroplasty. Pain was the most common reason for patients to seek an evaluation (241 of 282 shoulders). Shoulder function was substantially reduced at presentation, with patients only able to perform an average of 2.6 of 12 SST functions. Overall, technical factors such as component malpositioning and glenohumeral malalignment were the most common characteristics identified among all the shoulders. Loosening of glenoid components was noted in 85 of the 136 total shoulder arthroplasties, and glenoid erosion was found in 51 of 80 hemiarthroplasties performed for degenerative conditions. Patients with an unsatisfactory outcome after shoulder arthroplasty present with poor shoulder function and pain. Component malposition, glenohumeral malalignment, and glenoid failure are all prevalent features among patients with an unsatisfactory outcome.

The types and severity of complications associated with interscalene brachial plexus block anesthesia: local and national evidence

Interscalene brachial plexus block is a commonly used anesthetic. However, substantial complications can be associated with its use. Our study included 15 years of data from a local medical center and 3 decades of records from the national American Society of Anesthesiology Closed Claims Project. The hospital had 27 peripheral neurologic injuries, 3 central nervous system complications, 6 respiratory complications, and 5 cardiovascular complications. Of these complications, 14 were still present at the most recent follow-up, some causing major compromise of the patient's comfort and function. All central blocks, local toxicities, and respiratory complications resolved. In the hospital series, more experienced anesthesiologists tended to have lower complication rates. The American Society of Anesthesiology Closed Claims database had 20 peripheral neurologic injuries, 10 respiratory complications, 5 central nervous system complications, 4 deaths, 2 emotional disturbances, and 1 other unknown event. Of the complications, 19 were described as permanent. Interscalene brachial plexus block can be accompanied by substantial and disabling complications, especially when administered by less experienced anesthesiologists.

Shoulder arthroplasty: the socket perspective

Although much attention has been directed to the development of the humeral components used in shoulder arthroplasty, the major unsolved challenge lies on the glenoid side of the articulation. This challenge arises from difficulties resisting eccentric loading and providing adequate implant-bone fixation. Current glenoid component designs use polyethylene and polymethyl methacrylate and are prone to loosening, plastic deformation, particulate debris, and third-body wear. Metal-backed components present further challenges, and results have generally been disappointing. There is interest in biologic resurfacing procedures, including the interposition of fascia, capsule, or meniscal allograft and nonprosthetic glenoid arthroplasty, or what has become known as the "ream-and-run" procedure. Despite encouraging results, important questions remain unanswered about these procedures. However, each may warrant further exploration with a goal of providing an effective and durable approach to glenoid arthritis that avoids the risks associated with polymethyl methacrylate and polyethylene.

Arthroscopic compared with open repairs for recurrent anterior shoulder instability. A systematic review and meta-analysis of the literature

BACKGROUND

Both arthroscopic and open surgical repairs are utilized for the management of anterior glenohumeral instability. To determine the evidence supporting the relative effectiveness of these two approaches, we conducted a rigorous and comprehensive analysis of all reports comparing arthroscopic and open repairs.

METHODS

A systematic analysis of eighteen published or presented studies was performed to determine if there were significant differences between the two approaches with regard to recurrence (recurrent dislocation, subluxation, and/or apprehension and/or a reoperation for instability), return to work and/or sports, and Rowe scores. We also performed subgroup analysis to determine if the quality of the study or the arthroscopic technique influenced the results.

RESULTS

We identified four randomized controlled trials, ten controlled clinical trials, and four other comparative studies. Results were influenced both by the quality of the study and by the arthroscopic technique. Meta-analysis revealed that, compared with open methods, arthroscopic repairs were associated with significantly higher risks of recurrent instability (p < 0.00001, relative risk = 2.37, 95% confidence interval = 1.66 to 3.38), recurrent dislocation (p < 0.0001, relative risk = 2.74, 95% confidence interval = 1.75 to 4.28), and a reoperation (p = 0.002, relative risk = 2.32, 95% confidence interval = 1.35 to 3.99). When considered alone, arthroscopic suture anchor techniques were associated with significantly higher risks of recurrent instability (p = 0.01, relative risk = 2.25, 95% confidence interval = 1.21 to 4.17) and recurrent dislocation (p = 0.004, relative risk = 2.57, 95% confidence interval = 1.35 to 4.92) than were open methods. Arthroscopic approaches were also less effective than open methods with regard to enabling patients to return to work and/or sports (p = 0.03, relative risk = 0.87, 95% confidence interval = 0.77 to 0.99). On the other hand, analysis of the randomized clinical trials indicated that arthroscopic repairs were associated with higher Rowe scores (p = 0.002, standardized mean difference = 0.43, 95% confidence interval = 0.16 to 0.70) than were open methods. Similarly, analysis of the arthroscopic suture anchor techniques alone showed the Rowe scores to be higher (p = 0.04, standardized mean difference = 0.29, 95% confidence interval = 0.01 to 0.56) than those associated with open methods.

CONCLUSIONS

The available evidence indicates that arthroscopic approaches are not as effective as open approaches in preventing recurrent instability or enabling patients to return to work. Arthroscopic approaches resulted in better function as reflected by the Rowe scores in the randomized clinical trials. The study design and the arthroscopic technique had substantial effects on the results of the analysis.

The Bayesian "Star Paradox" Persists for Long Finite Sequences

The "star paradox" in phylogenetics is the tendency for a particular resolved tree to be sometimes strongly supported even when the data is generated by an unresolved ("star") tree. There have been contrary claims as to whether this phenomenon persists when very long sequences are considered. This note settles one aspect of this debate by proving mathematically that the chance that a resolved tree could be strongly supported stays above some strictly positive number, even as the length of the sequences becomes very large.

Principles for the evaluation and management of shoulder instability

During use of the normal shoulder, the humeral head is centered within the glenoid and the coracoacromial arch. When the shoulder cannot maintain this centered position during use, it is unstable. An unstable shoulder prevents normal function of the upper extremity. Shoulder instability is not the same as joint laxity. Joint laxity is a property of normal joints and allows the shoulder to attain its full range of functional positions. The concavity of the glenoid and the coracoacromial arch along with the passive and active forces that press the humeral head into the glenoid and the coracoacromial arch maintain the head in its centered position. This concavity-compression mechanism is dependent on the integrity of the glenoid and the coracoacromial arch, muscular compression, and restraining ligaments of the shoulder. Loss of any of these elements due to developmental, degenerative, traumatic, or iatrogenic factors may compromise the ability of the shoulder to center the humeral head in the glenoid.

A geometric approach to tree shape statistics

This article presents a new way to quantify the descriptive ability of tree shape statistics. Where before, tree shape statistics were chosen by their ability to distinguish between macroevolutionary models, the resolution presented in this paper quantifies the ability of a statistic to differentiate between similar and different trees. This is termed the geometric approach to differentiate it from the model-based approach previously explored. A distinct advantage of this perspective is that it allows evaluation of multiple tree shape statistics describing different aspects of tree shape. After developing the methodology, it is applied here to make specific recommendations for a suite of three statistics that may prove useful in applications. The article ends with an application of the statistics to clarify the impact of taxa omission on tree shape.

Direct injection of blood into the labrum enhances the stability provided by the glenoid labral socket

We tested the hypothesis that the stabilizing function of the labrum can be enhanced by inflating it with blood. In 6 fresh cadaveric glenoids, the anteroinferior stability provided by the glenoid was quantitated by measuring the maximal angle between the glenoid centerline and the direction of the force applied via a ball in the glenoid before the ball dislocated from the glenoid. This stability angle was measured for each of 4 different applied loads. These measurements were repeated after the anteroinferior labrum was augmented by the injection of fresh blood. Injection augmentation of the labrum significantly increased the measured stability angles in 5 of 6 specimens. The 1 outlier had a partial labral tear. The mean increase in stability for all 6 glenoids ranged from 19% to 30% for the different test loads. Labral injection with blood may be a useful adjunct in the surgical management of glenohumeral instability.