Biomedical subjects
Publications and source records attributed to J P Iannotti.
Instability of the shoulder is a common complication after prosthetic arthroplasty and accounts for approximately 4% to 5% of case series with mixed preoperative diagnoses. Several anatomic abnormalities and risk factors are associated with this problem. The direction of instability often is associated with the more common types of structural abnormalities.
BACKGROUND: The floating shoulder (ipsilateral fractures of the clavicular shaft and the scapular neck) is thought to be an unstable injury pattern requiring operative stabilization in most instances. This recommendation has been made with little biomechanical data to support it. The purpose of this study was to determine the osseous and ligamentous contributions to the stability of experimentally created scapular neck fractures in a cadaver model. METHODS: Standardized scapular neck fractures were made in twelve fresh-frozen human cadaveric shoulders. Each specimen was mounted in a specially designed testing apparatus and secured to a standard materials testing device. In group 1 (six shoulders), resistance to medial displacement was determined following sequential creation of an ipsilateral clavicular fracture, coracoacromial ligament disruption, and acromioclavicular capsular disruption. In group 2 (six shoulders), resistance to medial displacement was determined following sequential sectioning of the coracoacromial and coracoclavicular ligaments. RESULTS: The average measured force for all specimens (groups 1 and 2) after scapular neck fracture was 183 +/- 3.3 N (range, 166 to 203 N). The addition of a clavicular fracture (group 1) resulted in an average measured force of 128 +/- 10.5 N (range, 83 to 153 N), which corresponds to only a 30% loss of stability. Subsequent sectioning of the coracoacromial and acromioclavicular capsular ligaments yielded an average force of 126 +/- 9.1 N (range, 114 to 144 N), a 31% loss of stability, and 0 N, a complete loss of stability, respectively. Sectioning of the coracoacromial and coracoclavicular ligaments after scapular neck fracture (group 2) resulted in an average force of 103 +/- 8.4 N (range, 89 to 118 N), a 44% loss of stability, and 0 N, a complete loss of stability, respectively. CONCLUSIONS: Ipsilateral fractures of the scapular neck and the clavicular shaft do not produce a floating shoulder without additional disruption of the coracoacromial and acromioclavicular capsular ligaments. These and other unstable combined injury patterns are likely to be accompanied by substantial medial displacement of the glenoid fragment.
BACKGROUND: Arthroscopic capsular release is used to treat idiopathic adhesive capsulitis (frozen shoulder) that is refractory to nonoperative treatment or manipulation under anesthesia. The role of arthroscopic capsular release in the treatment of frozen shoulder after shoulder surgery or fracture is less clearly understood. The purposes of this study were to define the outcome of arthroscopic capsular release in the management of frozen shoulder after surgery or fracture and to compare these results with those of arthroscopic capsular release in the treatment of idiopathic frozen shoulder. METHODS: We evaluated the results of arthroscopic capsular release in three different groups of patients with shoulder contracture refractory to nonoperative management and manipulation under anesthesia. The three groups consisted of patients who had an idiopathic frozen shoulder, shoulder stiffness after surgery, or shoulder stiffness after fracture. We evaluated pain, function, patient satisfaction, and range of motion in all three groups before and after the study treatment. RESULTS: At a mean of twenty months (range, twelve to forty-six months) after the operation, fifty patients were available for assessment of function and range of motion of the involved shoulder. At the time of follow-up, each group had a significant improvement in the scores for pain, patient satisfaction, and functional activity as well as in the overall outcome score (p < 0.01). Comparison of the scores among the different groups revealed that all had a similar degree of improvement in range of motion of the involved shoulder, but patients with postoperative frozen shoulder had significantly (p < 0.05) lower scores for pain (p < 0.03), patient satisfaction (p < 0.004), and functional activity (p < 0.002) than did those with idiopathic or post-fracture frozen shoulder. CONCLUSIONS: Arthroscopic capsular release was as effective for improving range of motion in patients with postoperative contracture of the shoulder as it was in patients with idiopathic and post-fracture contracture. However, there was less improvement in the subjective scores for pain, function, and patient satisfaction in the postoperative group.
The functional outcome of operative and nonoperative treatment of suprascapular neuropathy was compared to determine the preferred method of treatment for each etiology of nerve injury. The predictive value of preoperative electromyography also was studied. Fifty-three patients were evaluated at least 1 year (average, 28 months) from the time of operative (n = 36) or nonoperative (n = 17) treatment. A modified American Shoulder and Elbow Surgeons self-assessment score was obtained at presentation and at final followup. Electromyography data were obtained at initial presentation. Minimal electromyographic changes associated with denervation were associated with a limited response to treatment, especially in patients with nerve compression secondary to spinoglenoid notch cysts. Pretreatment electromyographic findings, therefore, were predictive of treatment response. Overall, operative and nonoperative treatment of these suprascapular nerve injuries resulted in significant functional improvement, but the results varied depending on the etiology of the injury. Spinoglenoid notch cysts responded significantly better to operative treatment, with the results for open surgery being the same as the results for arthroscopic decompression. In addition, compressive lesions attributable to suprascapular notch entrapment had the best improvement with surgical decompression. Traumatic lesions, including traction and direct closed injuries, had an equal response to operative and nonoperative treatment. Overuse injuries did not improve with operative treatment. Viral neuritis improved with nonoperative treatment and never was treated with surgery. Overall, traumatic injuries resulted in significantly worse final outcomes than any other etiologic processes. In the nonoperative group, neuropathy secondary to spinoglenoid cysts resulted in significantly worse function. The outcome of treatment is dependent on the severity and etiology of the nerve injury, and the method of treatment.
BACKGROUND: Rotator cuff repair is associated with good short or mid-term results, but to date there have been no long-term functional outcome studies demonstrating durability of results over time. In most long-term studies, the results have been compared with those of historical controls or with those of other, short-term follow-up studies. The purpose of the present prospective study was to evaluate short and long-term shoulder function after surgical repair in a single population of patients in order to follow changes over time. METHODS: Thirty-three patients underwent surgery, performed by one surgeon, for the treatment of a chronic, symptomatic, full-thickness rotator cuff defect. Data were obtained from questionnaires and physical examinations preoperatively, at two years, and at ten years. Identical standardized pain and function questionnaires were used and clinical evaluation was performed in a consistent fashion at all time-periods. The activity level, Constant score, level of disability, shoulder function score, and patient's subjective rating of the outcome were determined at the time of the final follow-up and compared with the same parameters at the two-year follow-up examination in order to determine if early results change with time. RESULTS: At the ten-year follow-up examination, there was no change in the raw Constant score determined at the two-year examination. When the Constant score was normalized for expected age-related changes, the percentage of patients who had a satisfactory result at ten years was even greater than the percentage at two years. Activity level decreased significantly over the time-period (p = 0.005). At the final follow-up examination, twelve patients worked at the same occupation as they had when the two-year examination was performed, two worked at a less strenuous occupation, and the remaining patients were retired. Only two patients retired because of problems related to the shoulder. The level of disability decreased over the study period, and there was a small improvement in the patients' self-assessment shoulder function score. The patients' subjective assessment of the outcome remained unchanged. CONCLUSIONS: The results of open rotator cuff repair for chronic tears do not deteriorate with time (ten years). The level of disability decreases, presumably because of a concurrent decrease in the activity level and in the demand on the shoulder as the patient ages. It is important to consider age-related changes when assessing the final outcome.
A surgical neck nonunion is a seriously debilitating complication of a proximal humerus fracture. Patients have virtually no functional use of their shoulders and experience pain. Successful treatment is reliable in relief of pain and potentially can restore function. The diagnosis is not difficult, however, a CT scan may be necessary to identify tuberosity or head-splitting fractures. Successful treatment for these nonunions is difficult but gratifying because the percent improvement is immense.
The management of humerus fractures is complicated by the presence of a prosthesis. Vigilance in addressing the mechanisms and predisposing factors for periprosthetic fracture may prevent their occurrence. In the event of a periprosthetic fracture, attention to prosthetic stability, fracture location and stability, and bone quality will help guide treatment decisions. Treatment should be commensurate with the goals of fracture stability, early rehabilitation, and maintaining a well-functioning prosthesis.
Four fresh frozen human cadavers (eight extremities) consisting of the head, neck, thorax, and entire upper extremities were used for dissection of the scapulothoracic articulation. In each specimen, the spinal accessory nerve, all relevant muscle insertions, and bursae were identified and measured. The structures of the scapulothoracic articulation can be divided into superficial, intermediate, and deep layers. The superficial layer consists of the trapezius, latissimus dorsi, and an inconsistent bursa between the inferior angle of the scapula and the latissimus dorsi. The intermediate layer consists of the levator scapulae, rhomboid minor and major, spinal accessory nerve, and scapulotrapezial bursa located between the superomedial scapula and the overlying trapezius. In all specimens, the spinal accessory nerve traveled intimately along the wall of the scapulotrapezial bursa, an average of 2.7 cm lateral to the superomedial angle of the scapula. The deep layer consists of the serratus anterior, subscapularis, and two bursae: one between the serratus and the thorax, the scapulothoracic bursa; and one between the subscapularis and the serratus, the subscapularis bursa.
The approach to management of a partial-thickness rotator cuff tear is best made with the understanding that this is not a singular condition. Rather, partial tears represent the common outcome of a variety of insults to the rotator cuff. Degenerative changes due to aging, anatomic impingement, and trauma may all be etiologic agents. Overhead athletes may develop tears due to repetitive microtrauma or internal impingement. Outlet radiographs and magnetic resonance imaging are recommended for routine preoperative evaluation. A nonoperative treatment program for rotator cuff strengthening and stretching is appropriate as initial treatment; modification of activities and anti-inflammatory medication are often used as well. Operative management may be considered when nonoperative treatment fails. Arthroscopic evaluation is required to determine the true extent of the cuff lesion. Arthroscopic subacromial decompression is recommended when outlet impingement is present. Rotator cuff debridement or formal cuff repair is dependent on the size of the cuff defect and the age and activity level of the patient. The importance of recognizing the different causes of partial-thickness rotator cuff tears is emphasized in this review of pathogenesis, clinical diagnosis, imaging, and treatment.
OBJECTIVE: The field of shoulder kinematics research has long relied upon the use of cadaveric models or invasive techniques in human volunteers. In this paper, a novel method is presented that utilizes magnetic resonance imaging (MRI) and a software system called 3DVEWNIX. This method permits non-invasive, repetitive evaluation of living patients for glenohumeral kinematics analysis. The objectives of this study were twofold: to validate the quantitative accuracy of this technique; and to demonstrate glenohumeral relationships in asymptomatic volunteers during internal and external rotation of the arm. DESIGN: The translational accuracy was first assessed by comparing known cadaveric glenohumeral translations with calculations from MR images of the cadaver. Nine asymptomatic volunteers were subsequently placed in an external shoulder positioning device in the scanner and imaged in 10 degrees increments of actively achieved internal and external rotation. Three-dimensional reconstructions of the glenoid and humerus were used to evaluate the glenohumeral relationships in the tested positions of rotation. RESULTS: The quantitative analysis revealed an error of 0.61 mm (SEM 0.11 mm). Examination of the volunteers demonstrated normal relationships about the glenohumeral joint in internal and external rotation. In addition, this method provided detailed images of the bony surface architecture from any perspective. These images can be transformed into a cinematic three-dimensional depiction of active shoulder rotation. CONCLUSION: This new technique offers an accurate, non-invasive method for assessing the normal glenohumeral relationships in shoulder kinematics. We now possess the capability to investigate the kinematics of normal and abnormal shoulder conditions non-invasively in a large patient population.
There are many anatomic and biomechanical factors that define the structure and function of the normal glenohumeral joint. These factors influence the design and function of the prosthetic shoulder. Our best efforts in shoulder design should reflect an attempt to reproduce the normal structure-function relationships of the natural glenohumeral joint. Prosthetic design must also take into account the variable anatomic abnormalities associated with the pathologic condition. Prosthetic designs should attempt to facilitate the surgical correction of this pathology, with the goal of reproducing normal anatomy. Optimal prosthetic reconstruction of the shoulder is dependent on prosthetic design, prosthetic soft tissues, postoperative healing and rehabilitation, and the long-term biologic response to the implant. The success of any prosthetic reconstruction is dependant on many factors, and in some cases, normal anatomy and function cannot be achieved entirely by prosthetic design.
Pain following total shoulder arthroplasty or humeral hemiarthroplasty is uncommon. Impingement syndrome can be an infrequent source of pain following shoulder arthroplasty. We retrospectively reviewed six patients with refractory impingement syndrome treated with arthroscopic acromioplasty following either total shoulder arthroplasty (four patients) or humeral hemiarthroplasty (two patients). Chronic impingement syndrome requiring acromioplasty affected 3% of all patients who underwent total shoulder arthroplasty or humeral hemiarthroplasty during the study period. A thorough history, physical examination, and radiographic findings made the clinical diagnosis of impingement syndrome. All six patients had positive impingement signs and a positive impingement test with subacromial lidocaine injection. Preoperative radiographs revealed a type II or III acromion and subacromial outlet narrowing in five of six patients. Other sources of shoulder pain including prosthesis loosening, infection, and rotator cuff tear were ruled out preoperatively by physical examination and radiographic findings, and were confirmed by arthroscopic examination. The results of arthroscopic acromioplasty were a reduction in pain from 7.5 preoperatively to 1.6 postoperatively, on a scale from 0 to 10. Five of six patients were completely satisfied with the results of their arthroscopic surgery. Overall, according to the University of California at Los Angeles end-result score, the results were rated as excellent or good in five patients, and unsatisfactory in one patient. Arthroscopic acromioplasty can be a successful technique for the treatment of chronic impingement syndrome following total shoulder arthroplasty or hemiarthroplasty in appropriate patients.
The objective of this study was to examine how changes in glenohumeral joint conformity and loading patterns affected the forces and strains developed at the glenoid. After removal of soft tissue (muscles, ligaments, and labrum), force-displacement data were collected for both natural and prosthetically reconstructed joints. Joints were shown to develop higher forces for a given translation as joint conformity increased. A rigid body model of joint contact forces was used to determined the so-called effective radial mismatch of each joint. For the purposes of this study, the effective radial mismatch is defined as the mismatch required for a rigid body joint to have the same force-displacement relationship as the joint in question. This parameter is an indication of the deformation at the articular surface. The effective radial mismatch dramatically increased with increasing medial loads, indicating that under physiological loads, the effective radial mismatch of a joint is much greater than its measured mismatch at no load. This increase in effective mismatch as medial loads were increased was found to be threefold greater in cartilaginous joints than in reconstructed joints. Rosette strain gages positioned at the midlevel of the glenoid keel in the reconstructed joints revealed that anterior/posterior component loading leads to fully reversible cyclic keel strains. The highest compressive strains occurred with the head centered in the glenoid, and were larger for nonconforming joints (epsilon = 0.23 percent). These strains became tensile just before rim loading and were greater for conforming joints (epsilon = 0.15 percent). Although recorded peak strains are below the yield point for polyethylene, the fully reversed cyclic loading of the component in this fashion may ultimately lead to component toggling and implant failure.
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We retrospectively reviewed the medical records, operative reports, and preoperative and postoperative radiographs of thirty-nine patients who had been managed operatively for malunion of a fracture of the proximal aspect of the humerus. The malunions were categorized according to the presence of osseous abnormalities, including malposition of the greater or lesser tuberosity (type I; twenty-eight patients), incongruity of the articular surface (type II; twenty-six patients), and malalignment of the articular segment (type III; sixteen patients). Soft-tissue abnormalities, such as soft-tissue contracture, a tear of the rotator cuff, and impingement, were also recorded. At an average of forty-four months (range, twelve to fifty-three months) postoperatively, the patients were assessed for pain relief, the range of motion of the shoulder, and the ability to perform activities of daily living. The result was satisfactory for twenty-seven patients (69 per cent) and unsatisfactory for the remaining twelve (31 per cent) at the latest follow-up evaluation. Of the twenty-seven patients who had a satisfactory result, twenty-six (96 per cent) had had complete operative correction of all osseous and soft-tissue abnormalities. Of the twelve patients who had an unsatisfactory result, four had had complete operative correction of these abnormalities (p < 0.0001). Twenty-six patients (67 per cent) had incongruity of the glenohumeral joint at the time of presentation. Twenty-three of these patients had the incongruity corrected with prosthetic arthroplasty (twenty-two) or arthrodesis of the glenohumeral joint (one); the result was satisfactory for seventeen (74 per cent). In contrast, the result was unsatisfactory for all three patients in whom the incongruity had not been corrected at the time of the operation (p = 0.01). Eleven patients had malposition of the greater or lesser tuberosity but a congruent joint surface preoperatively. Ten patients in this group were managed with either osteotomy of the tuberosity or acromioplasty, and nine of them had a satisfactory result at the latest follow-up evaluation. The result was unsatisfactory for one patient who was managed with only correction of a soft-tissue contracture (that is, no treatment of the malposition) (p = 0.05). Both osseous and soft-tissue abnormalities were identified as the cause of pain and stiffness in patients who had malunion of a fracture of the proximal aspect of the humerus. We concluded that operative management of these patients is successful only if all osseous and soft-tissue abnormalities are corrected at the time of the operation.
Resection of the lateral end of the clavicle disrupts the acromioclavicular articulation and creates the potential for abnormal postoperative motion. Seventeen isolated distal clavicle resections were reviewed to assess translation of the acromioclavicular articulation in the anteroposterior plane and its relationship to patient outcome. Stress radiographs were used to quantitate the translation of the distal clavicle and the amount of bone resected. Radiographs of the contralateral shoulder served as a control. Patients completed a questionnaire on shoulder function and pain and were examined preoperatively and postoperatively. The total translation (anterior plus posterior) in the anteroposterior plane averaged 8.7 mm (range, 3-21 mm) for surgically treated shoulders and was significantly greater than that for the contralateral shoulders (mean, 3.2 mm; range, 1-6 mm). Patients' postoperative visual analog pain scales correlated with the magnitude of anteroposterior translation. The amount of translation and the postoperative pain scores did not correlate with the apparent joint space seen on radiographs after surgery. The correlation of pain scores with the amount of translation shows that excessive anteroposterior instability of the distal clavicle can cause postoperative shoulder pain and poor surgical outcome.
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