Pathomechanics in atraumatic shoulder instability: scapular positioning correlates with humeral head centering.

The objective was to analyze three-dimensional scapular positioning and glenohumeral centering of normal and atraumatic unstable shoulders. We hypothesized that changes of humeral head position correlate with alterations of scapular positioning. The shoulders of 28 healthy volunteers and 14 patients with atraumatic instability were examined in various arm positions using open magnetic resonance imaging. After segmentation and three-dimensional reconstruction, three-dimensional analyses of scapular positioning and humeral head position relative to the glenoid were done. The coefficient of correlation (r) between both parameters was determined using the correlation z test. The glenohumeral to scapulothoracic ratio in the scapular plane was increased in nine of 14 patients and decreased in three patients, whereas the scapular internal rotation in the transverse plane was increased in all unstable shoulders. The unstable shoulders also had malcentering (greater than two times the standard deviation in the healthy volunteers) of the humeral head in the direction of instability during various arm positions. In healthy and unstable shoulders, the correlation between scapular position and glenohumeral positioning was high during passive elevation (r = 0.60-0.87). The high correlation suggests that scapular positioning is relevant for humeral head decentering. Therefore, physiotherapeutic strategy should consider the malpositioning of the scapula and be adapted to the direction of instability.

The magnitude and durability of functional improvement after total shoulder arthroplasty for degenerative joint disease.

So that patients with degenerative glenohumeral joint disease who wish to consider total shoulder arthroplasty will be better informed, we sought to document the magnitude and durability of the improvement in shoulder function after this procedure. The function of 124 shoulders with primary degenerative joint disease was documented by patient self-assessment with the Simple Shoulder Test before and sequentially after total shoulder arthroplasty performed with a standardized technique. Patients reported that they could perform 3.8 +/- 0.3 (SEM) of the 12 Simple Shoulder Test functions before surgery. The total number of performable functions was consistent at different follow-up intervals: 8.0 +/- 0.4 at 6 months, 9.5 +/- 0.4 at 1 year, 10.0 +/- 0.3 at 2 years, 9.2 +/- 0.4 at 3 years, 9.6 +/- 0.4 at 4 years, and 10.0 +/- 0.4 at 5 years. We conclude that total shoulder arthroplasty can provide substantial and durable improvement in shoulder function.

Intrinsic stability of unused and retrieved polyethylene glenoid components.

The surface geometry of polyethylene components can be altered by in vivo use. The purpose of this investigation is to document the effects of these changes on the intrinsic stability provided by the glenoid component. We validated a method of measuring the intrinsic stability of glenoid components as indicated by the balance stability angle (the maximal angle between the glenoid centerline and the resultant humeral force before dislocation of the humeral head occurs). We compared observed values with those predicted for unused glenoid components for which the geometry was known. We then applied this method to retrieved glenoid components in which the surface geometry had been altered by in vivo use. The balance stability angles measured in retrieved glenoids were often substantially reduced: 11 of 24 glenoids had diminished balance stability angles of at least 30% in at least one direction. We concluded that the surface geometry of polyethylene glenoid components can be altered by in vivo use in a manner that may compromise their contribution to glenohumeral stability.

Improvement in comfort and function after cuff repair without acromioplasty.

The repair of full thickness rotator cuff tears traditionally has included acromioplasty and coracoacromial ligament section. Acromioplasty can be complicated by deltoid detachment, compromise of the deltoid lever arm, anterosuperior instability, and adhesions of the rotator cuff tendons under the bleeding cancellous bone of the osteotomized acromion. This report concerns the improvement in shoulder function at a minimum of 2 years after 27 full thickness rotator cuff repairs were done without deltoid detachment, acromioplasty, or section of the coracoacromial ligament. The mean number of Simple Shoulder Test functions that the patients could do increased from six of 12 before surgery to 10 of 12 at an average followup of 4 years after surgery. Eight of 12 individual Simple Shoulder Test functions were significantly improved after the procedure. There also was a significant improvement in the Short Form-36 comfort, physical role function, and mental health scores. When done without acromioplasty, cuff repair avoids the possibility of deltoid detachment, altered deltoid mechanics, anterosuperior instability, and tendon scarring to the cancellous undersurface of the acromion.

Observations on retrieved polyethylene glenoid components.

It is recognized that retrieved polyethylene hip and knee components may undergo substantial changes from their preimplantation form. Little information is available, however, regarding retrieved polyethylene glenoid components. We report on 39 glenoid components removed at an average of 2.5 years after implantation. Of components for which clinical data were available, the commonest reason for the revision arthroplasty was loosening of the glenoid component; many components also showed glenohumeral instability. The articular surface contours of most of the components were altered. Of components, 28 had obvious erosion of the rim, 27 had surface irregularities, 11 were fractured, and 9 had central wear. These observations in retrieved glenoid components point to the potential of polyethylene for deformation in vivo, especially when the mechanics of the arthroplasty are compromised.

Outcome of nonoperative management of full-thickness rotator cuff tears.

The study documented the functional outcome in a consecutive series of 46 patients from an individual practice meeting the inclusion criteria of (1) a full-thickness rotator cuff tear seen by ultrasonography, arthrogram, or magnetic resonance imaging, (2) absence of a Workers' Compensation claim or previous surgery, (3) followup of at least 1 year, and (4) election of nonoperative management by the patient. Twenty-six of the tears involved only the supraspinatus, two involved the supraspinatus and infraspinatus, and two involved the supraspinatus, infraspinatus, and subscapularis (16 reports did not specify the size of the tear). Treatment consisted only of patient education and a home program of gentle stretching and strengthening. Patients completed the Simple Shoulder Test at the initial visit and sequentially at 6-month intervals thereafter. At an average followup of 2.5+/-1.6 years, 27 (59%) patients experienced improvement with nonoperative treatment, 14 (30%) patients experienced worsening, and five (11%) patients remained unchanged. The average number of Simple Shoulder Test functions the patients could perform initially was 5.6+/-3.2. At the latest followup, the average number of Simple Shoulder Test functions the patients could perform improved to 7.0 +/-3.8. The ability to sleep on the affected side and the ability to place the hand behind the head were significantly improved.

Do shoulder patients insured by workers' compensation present with worse self-assessed function and health status?

The purpose of this study was to test the hypothesis that patients whose shoulder problems are covered by workers' compensation insurance perceive worse shoulder function and health status than do comparable patients whose problem is not covered by workers' compensation. Each of 1063 consecutive patients presenting with shoulder problems to an individual consultant completed 2 questionnaires: the Simple Shoulder Test inventory of shoulder function and the Short Form 36 general health assessment. The patients were divided into 2 groups on the basis of whether care of the shoulder problem was covered by injured workers' compensation insurance. The results indicate that patients whose shoulder condition is covered by workers' compensation have significantly lower self-assessed shoulder function and health status than do those patients whose shoulder conditions are not related to on-the-job injuries. The differences between the workers' compensation and non-workers' compensation groups could not be attributed to differences in age, sex, or diagnosis.

A prospective, multipractice study of shoulder function and health status in patients with documented rotator cuff tears.

A total of 191 patients from 29 orthopedic practices are analyzed in this report. All had full-thickness tears documented by imaging tests and/or surgical observation; 190 had tears of the supraspinatus, 54 had tears of the infraspinatus, and 13 had tears of the subscapularis. The greatest functional deficits were in the ability to place 8 pounds on a shelf at the level of the head (93% unable), the ability to throw overhand (93% unable), and the ability to sleep on the affected side (86% unable). The SF-36 physical role function and comfort scores were 27% and 48%, respectively, of those of age- and sex-matched controls. Of the variables suggested by a review of the literature, only female sex, involvement of the infraspinatus in the cuff tear, and workers' compensation claims were significantly correlated with lower shoulder function in this series of patients.

Correlations with patients' perspectives of the result of lower-extremity amputation.

BACKGROUND: Patients' perceptions of the result of lower-extremity amputation vary widely, yet the factors associated with this variability are not well understood. Our objective was to identify important correlations with the perceived result that may help to indicate the factors that deserve particular emphasis in the management of patients who have had an amputation. METHODS: In this retrospective study, 148 patients who had had a major lower-extremity amputation completed a standardized questionnaire designed to assess the demographic characteristics, comorbidities, amputation characteristics, prosthetic function, and social function at a mean of seven years after surgery. We correlated each of these variables with four result metrics: general satisfaction, quality of life, freedom from frustration, and walking distance. RESULTS: The four result metrics were significantly and strongly correlated with (1) the comfort of the residual limb; (2) the condition of the contralateral limb; (3) the comfort, function, and appearance of the prosthesis; (4) social factors; and (5) the ability to exercise recreationally (p < 0.0001). Interestingly, the level and laterality of the amputation were not significantly correlated with the patients' perceived result. CONCLUSIONS: The perceived result of amputation is not associated with the amount of the limb that was amputated but rather with factors that may be optimized by surgical, prosthetic, and social management.

Challenges in evaluating patients lost to follow-up in clinical studies of rotator cuff tears.

BACKGROUND: Long-term follow-up studies are necessary to critically evaluate the outcome of a treatment intervention for a specific disorder. However, patients may cease participating in a long-term study and become lost to follow-up; thus, their current condition is unknown. The underlying characteristics that predispose a patient to become lost to follow-up are difficult to identify and control. Patients who are lost to follow-up may be contacted by telephone; however, the effect of administering a functional assessment questionnaire by telephone compared with that of mailing a questionnaire is unknown. The purpose of this study was to compare patients who continued to respond to requests for follow-up with those who did not. A second purpose was to compare responses obtained by mail with those obtained by telephone interview. METHODS: Two hundred and twenty-four patients with a rotator cuff tear were enrolled in an ongoing study of shoulder function and general health. Self-assessment questionnaires were mailed to every patient at six-month intervals. Sixty-seven patients (30 percent) regularly responded to mailings (identified as responders in this study), fifty-five patients (25 percent) responded occasionally (these patients were not included in the analysis), and 102 patients (46 percent) ceased to respond and became lost to follow-up (identified as nonresponders in this study). This investigation was performed to determine: (1) the characteristics of nonresponders compared with those of responders, (2) the functional status of nonresponders as assessed with a questionnaire over the telephone, and (3) the effect of administering a self-assessment functional questionnaire by telephone compared with that of sending the same questionnaire by mail. RESULTS: Nonresponders tended to have lower initial scores for the mental health summary (p = 0.03) and for social function (p = 0.01), were less likely to have had surgery (p = 0.009), and were less likely to consume alcohol (p = 0.03). At the last known time when they completed the mailed questionnaire, nonresponders reported significantly worse shoulder function than responders (p = 0.0001). However, on telephone questioning the mean number of shoulder functions that the nonresponders indicated that they could perform was greater than the mean number documented on their last mailed questionnaire (p < 0.0001). In a random subgroup of responders, the mean number of functions that the patients indicated that they could perform when interviewed by telephone was significantly greater than the number indicated on their most recent mailed questionnaire (p < 0.01). The results obtained by telephone from this random subgroup of responders were similar to those obtained by telephone from the nonresponders. CONCLUSIONS: There are differences between patients who continue to participate in a study and those who become lost to follow-up. Functional assessment questionnaires administered by telephone yield different results than the same questionnaires sent by mail. These considerations are relevant to the design, implementation, and interpretation of clinical studies in which functional questionnaires are used.

Correlates with comfort and function after total shoulder arthroplasty for degenerative joint disease.

Although most patients are improved after shoulder arthroplasty, the degree of improvement is variable. The factors contributing to this variability are not well understood. In particular, little information is available regarding the preoperative characteristics of the patient that may influence the quality of the result. This study correlated patient demographics, preoperative health status, and preoperative shoulder function with 3 outcome metrics: comfort, physical role function, and shoulder-specific function. One hundred thirty-four shoulders having total shoulder arthroplasty for degenerative glenohumeral joint disease had an average follow-up of 3.4 +/- 1.8 years. The SF-36 Comfort score improved from 39 to 61 (P < .0001). The SF-36 Physical Role Function score improved from 30 to 52 (P < .0001). The average number of Simple Shoulder Test functions performable (out of 12) improved from 4 to 9 (P < .0001). The strongest correlates with postoperative comfort included preoperative physical function (P < .0001), general health (P < .0001), and social function (P < .001). The strongest correlates with postoperative physical role function included preoperative physical function (P < .0001) and general health (P < .001). The strongest correlates with postoperative shoulder function included male gender (P < .0001), and preoperative physical function (P < .0001), social function (P < .0001), mental health (P < .0001) and shoulder function (P < .0001). These data indicate that the overall well-being of the patient before surgery is strongly correlated with the quality of the outcome from total shoulder arthroplasty for degenerative glenohumeral joint disease.

Self-assessment questionnaires document substantial variability in the clinical expression of rotator cuff tears.

The goal of this investigation was to document the variability in the clinical expression of full-thickness rotator cuff tears with practical and standardized patient self-assessment tools. One-hundred twenty-three consecutive patients with full-thickness cuff tears diagnosed by standard cuff-imaging methods (sonography, arthrography, or magnetic resonance imagery) assessed their own shoulder function and health status with the Simple Shoulder Test and the Short Form 36, respectively. As a group, these patients were substantially compromised in their ability to perform the functions of the Simple Shoulder Test and in the Short Form 36 scales of physical role, physical function, and comfort. As individuals, however, their self-assessments varied widely. The standard deviations were often greater than 50% of the mean and the range of responses often covered the entire scale from the minimum possible score to the maximum possible score. These results show the importance of documenting the clinical expression of cuff tears in patients at initial evaluation and when treatment is being considered. The results also show the practicality of standardized self-assessment questionnaires in such documentation.

Simple home program for frozen shoulder to improve patients' assessment of shoulder function and health status.

BACKGROUND: The purpose of this investigation was to test the hypothesis that a simple home program can improve the self-assessed shoulder function and health status of a group of patients with frozen shoulders. METHODS: A case series using a one-group pretest, posttest design analyzing 41 patients from a single orthopedic practice who had a frozen shoulder were included in this study. The patients completed the Simple Shoulder Test (SST) and the Medical Outcomes Study Short-Form Health Survey (SF-36) questionnaire at the time of initial consultation, had treatment consisting of education regarding frozen shoulder and home stretching instructions, and were asked to complete the same questionnaires mailed every 6 months. Initial results were compared with previously published control values to establish level of impairment, and follow-up results were compared with the initial results to determine the extent of improvement. RESULTS: Patients initially had serious deficits in the 12 shoulder functions inventoried by the SST and were also compromised in their general health status as reflected by the SF-36 scores. At follow-up, 4 of 10 SST functions were improved (P < 0.001). The SF-36 health status scores of physical function, comfort, and physical role function were also improved (P < 0.001). CONCLUSION: These data suggest that this home program for frozen shoulder can lead to improved self-assessed shoulder function and health status in patients similar to those in the study population.

Posteroinferior glenoplasty can change glenoid shape and increase the mechanical stability of the shoulder.

The treatment of recurrent posterior glenohumeral instability remains an unsolved clinical problem. Although various types of capsulorraphy have been advocated, outcome studies indicate that it is difficult to achieve a balance between stability and mobility. Alterations of the bony glenoid for posterior instability have been proposed, but are not well understood from a mechanical perspective. This investigation had 2 purposes: (1) to determine in a cadaver model if posteroinferior glenoplasty can change the shape of the glenoid, and (2) to determine if altering the shape of the glenoid can increase the mechanical stability of the glenohumeral joint. We determined the effective glenoid shape in 7 normal cadaver glenoids by tracking the path of the center of the humeral head as it was translated across the glenoid face in 8 different directions. These determinations enabled us to calculate the maximum effective slope of the glenoid in each direction. We then determined the mechanical stability of the glenoids in each of the 8 directions by measuring the tangential force required to dislocate the shoulder under a 50-N compressive load. The ratio of the dislocating force to the compressive load was defined as the stability ratio. All measurements were repeated after a standardized posteroinferior glenoplasty was performed. Posteroinferior glenoplasty increased the posteroinferior glenoid depth from 3.8 +/- 0.6 mm to 7.0 +/- 1.8 mm and shifted the center of the humeral head an average of 2.2 mm anteriorly and 1.8 mm superiorly. These changes in dimension could be directly visualized as an immediate mechanical consequence of the glenoplasty procedure, particularly because of the insertion of the bone wedge. Glenoplasty increased the posteroinferior glenoid slope from 0.55 +/- 0.07 to 0.83 +/- 0.12 and increased the posteroinferior stability ratio from 0.47 +/- 0.10 to 0.81 +/- 0.17. This is a more than 70% increase in the tangential force that can be resisted before dislocation. The increase can be quantitatively understood as a direct mechanical consequence of the altered shape of the glenoid concavity. These numbers indicate that, in this cadaveric model, posteroinferior glenoplasty results in defined changes in the effective glenoid shape and in the mechanical stability of the glenohumeral joint. However, this study does not establish the role of this procedure in the clinical management of posterior glenohumeral instability.

Reexpression of type IIA procollagen by adult articular chondrocytes in osteoarthritic cartilage.

OBJECTIVE: To test for the reexpression of the chondroprogenitor splice variant of the gene COL2A1, type IIA procollagen (containing a cysteine-rich NH2 propeptide), in adult articular chondrocytes in osteoarthritic (OA) joint disease. METHODS: In situ hybridization and immunohistochemical localization were performed on normal and OA articular cartilage specimens. The presence of type IIA procollagen messenger RNA (mRNA) expression was confirmed by Northern blot analysis. RESULTS: In normal articular cartilage, no expression of mRNA or presence of type IIA procollagen was found. In OA articular cartilage, focally intense staining for type IIA protein was detected. Consistent with this, chondrocytes, particularly in the middle zones of articular cartilage, expressed type IIA procollagen mRNA. OA repair cartilage typically showed a broad zone of cells expressing type IIA mRNA and protein. CONCLUSION: Type IIA procollagen is reexpressed by adult articular chondrocytes in OA cartilage degeneration, indicating the potential reversion of the cells to a chondroprogenitor cellular phenotype. The absence of type IIA mRNA and protein in normal adult articular cartilage and its onset in the diseased state suggests type IIA procollagen as a marker of OA.

Monitoring for compartmental syndrome using near-infrared spectroscopy: a noninvasive, continuous, transcutaneous monitoring technique.

BACKGROUND: The diagnosis of compartmental syndrome (CS) may be delayed because current monitoring techniques are invasive and intermittent and the compartment pressure (CP) that predicts ischemia is variable. Fiber-optic devices using near-infrared (NIR) wavelength reflection can determine the redox state of light-absorbing molecules and have been used to monitor venous hemoglobin saturation to detect ischemia during low-flow states. The purpose of this study was to determine if NIR spectroscopy can provide continuous, transcutaneous, noninvasive monitoring for muscle ischemia in an animal model of CS. METHODS: Nine swine were anesthetized and a 20-mm NIR probe was placed over the anterolateral compartment of the hind leg to provide continuous determination of muscle oxyhemoglobin level. Needles were inserted into the compartment to measure CP. A nerve stimulator was placed over the peroneal nerve to induce dorsiflexion twitch. Albumin was infused into the muscle to incrementally increase CP until there was complete loss of dorsiflexion, then after 20 minutes fasciotomy was performed. RESULTS: All animals lost dorsiflexion at CP of 43+/-14 mm Hg. There was a significant inverse correlation between CP and oxyhemoglobin level (r = -0.78; p < 0.001) and a correlation between oxyhemoglobin and perfusion pressure (mean arterial pressure minus CP) (r = 0.66; p < 0.001). Redox state was a more consistent predictor of twitch loss than perfusion pressure. CONCLUSION: Muscle oxyhemoglobin level measured by NIR spectroscopy strongly reflected CP, perfusion pressure, and loss of dorsiflexion twitch. Currently available portable NIR devices may provide the benefit of continuous, noninvasive monitoring for CS. Further studies to determine the role of this technology in the detection of compartmental syndrome are warranted.

The lateral impaction of the shoulder.

17 patients had radiographic demonstration of injury to the clavicle, scapula and ribs from an impact delivered to the lateral shoulder. The study included 13 males and 4 females whose ages ranged from 18 to 83 years (average 45 years). Most injuries were sustained in falls or motor vehicle accidents. Analysis of these cases suggests a biomechanical hypothesis concerning the transmission of the impact forces within the shoulder girdle. According to this hypothesis, the impaction force applied to the lateral shoulder is transmitted from outside inward following two paths. The anterior and superior path passes through the acromio-clavicular joint, the clavicle, the costo-clavicular joint and the sterno-clavicular joint. The posterior and inferior path is transmitted within the gleno-humeral joint, the scapula and the scapulo-thoracic joint. Major impacting force is required to disrupt the anterior and posterior arches of the shoulder girdle. When both of these supporting structures are damaged, the patient is at risk for more serious injuries, including disruption of the thorax, shoulder joint, brachial plexus and neck.

The correlation of comorbidity with function of the shoulder and health status of patients who have glenohumeral degenerative joint disease.

We studied the effect of comorbidities on function of the shoulder and health status in a group of eighty-five consecutive patients who had glenohumeral degenerative joint disease of sufficient severity to meet one surgeon's criteria for the performance of shoulder arthroplasty. A questionnaire was used to identify the comorbidities, such as other diseases, social factors, or a work-related injury, for each patient. The number of functions on the Simple Shoulder Test that the patient could perform had a significant negative correlation with the number of comorbidities (r = -0.32, intercept = 4.6 per cent, slope = -0.6, and p = 0.0031). Each parameter on the Short Form-36 (except for physical role function) had a significant negative correlation with the number of comorbidities (p < 0.05). This negative relationship was strongest for general health perception (r = -0.42) and vitality (r = -0.35). We concluded that the number of comorbidities has a quantitative effect on function of the shoulder. In the evaluation of the functional status of patients and the effectiveness of treatment, the effects of comorbidity must be controlled. The results of the present study demonstrate that the scores on the Short Form-36 are quantitatively related to the number of comorbidities. The six parameters that are unrelated to function of the shoulder (physical function, social function, emotional role function, mental health, vitality, and general health perception) may provide a practical way to integrate the effects of all potential comorbidities on individual patients. Future clinical research will be strengthened by efforts to measure the impact of comorbidities and by strategies to control for their effects.

Total shoulder arthroplasty versus hemiarthroplasty. Current trends.

Currently, a debate exists regarding the indications for hemiarthroplasty and total shoulder arthroplasty. A number of factors are important in making this decision. The article discusses some of the variables related to choosing the appropriate procedure for every patient. The authors also discuss their approach to various arthritic conditions of the shoulder, the rationale behind their approach, and their results. Future work will be necessary before more definitive recommendations can be made, and they may well be different for each individual surgeon.

The humeroscapular motion interface.

Motion between the humerus and scapula commonly is described as glenohumeral motion. However, humeroscapular motion occurs at two distinct sites. In addition to the motion at the diarthrodial glenohumeral joint, movement occurs between the proximal humerus and related structures and the surrounding sleeve of structures, including the acromion, deltoid, coracoid, coracoacromial ligament, and the muscles attached to the coracoid. This site of nonarticular shoulder motion is defined as the humeroscapular motion interface. Nonarticular humeroscapular motion can be documented and measured using standard magnetic resonance imaging techniques. The maximum average interfacial motion using axial images was 29.1 mm, which occurred at the level of the maximum diameter of the humeral head. Interfacial motion varied depending on the site measured. If pathologic conditions such as adhesions secondary to trauma or surgery interfere with or obliterate this space at sites of significant sliding motion, overall shoulder motion will be limited. Successful treatment of shoulder stiffness related to humeroscapular restraints is likely to require restoration of the normal sliding motion at the humeroscapular motion interface, in addition to resolving restraints affecting the glenohumeral joint motion.