Clinical effectiveness and safety of the extended humeral head arthroplasty for selected patients with rotator cuff tear arthropathy.

BACKGROUND: Cuff tear arthropathy is commonly managed with a reverse total shoulder arthroplasty (RTSA). A humeral hemiarthroplasty with an extended humeral head may provide a less invasive alternative for selected patients with cuff tear arthropathy if the shoulder has preserved active elevation. Because evidence regarding this procedure is limited, we investigated its safety and efficacy in treating selected patients with cuff tear arthropathy. METHODS: We analyzed the preoperative characteristics, surgical findings, and clinical outcomes for patients selected for extended head hemiarthroplasty. RESULTS: For 42 patients with 2-year follow-up, there were no complications or revisions. The Simple Shoulder Test score improved from a median of 3.0 to 8.0 (P < .001). The median percentage of maximal possible improvement was 50% (P < .001). The percentage of patients able to perform each of the functions of the Simple Shoulder Test was significantly improved; for example, the ability to sleep comfortably increased from 19% to 71%, and the ability to place a coin on the shelf at shoulder level increased from 38% to 86% (P < .001). CONCLUSIONS: There are circumstances in which RTSA is clearly the preferred procedure for cuff tear arthropathy, including pseudoparalysis, anterosuperior escape, and glenohumeral instability; however, in shoulders with preserved active motion and stability of the humeral head provided by an intact coracoacromial arch, the extended head humeral arthroplasty can enable selected patients to realize improved comfort and function without the potential risks of RTSA. Extended humeral head hemiarthroplasty can provide a safe and effective alternative for the management of selected patients with rotator cuff tear arthropathy and preserved active motion.

Suture spanning augmentation of single-row rotator cuff repair: a biomechanical analysis.

BACKGROUND: This in vitro study evaluated the biomechanical benefit of adding spanning sutures to single-row rotator cuff repair. METHODS: Mechanical testing was performed to evaluate 9 pairs of cadaveric shoulders with complete rotator cuff repairs, with a single-row technique used on one side and the suture spanning technique on the other. The spanning technique included sutures from 2 lateral anchors securing tendon near the musculotendinous junction, spanning the same anchor placement from single-row repair. The supraspinatus muscle was loaded to 100 N at 0.25 Hz for 100 cycles, followed by a ramp to failure. Markers and a video tracking system measured anterior and posterior gap formation across the repair at 25-cycle intervals. The force at which the stiffness decreased by 50% and 75% was determined. Data were compared using paired t-tests. RESULTS: One single-row repair failed at <25 cycles. Both anterior and posterior gap distances tended to be 1 to 2 mm larger for the single-row repairs than for the suture spanning technique. The difference was statistically significant at all cycles for the posterior gap formation (P ≤ .02). The trends were not significant for the anterior gap (P ≥ .13). The loads at which the stiffness decreased by 50% and 75% did not differ significantly between the 2 types of repair (P ≥ .10). CONCLUSIONS: The suture spanning technique primarily improved posterior gap formation. Decreased posterior gap formation could reduce failure rates for rotator cuff repair.

Mechanical properties of the flexor digitorum profundus tendon attachment.

The current study was performed to determine the strength and rigidity of the intact flexor digitorum profundus (FDP) tendon attachment and compare the rigidity at the attachment site to the rigidity within a more proximal part of the tendon. Eight cadaveric index fingers were tested to failure of the FDP tendon. Lines were drawn on each tendon with India ink stain at the position of the attachment to bone and 5 mm and 10 mm proximally. Each test was recorded using a high resolution video camera. A minimum of six images per test were used for analysis of tissue deformation. The centroid of each line was computationally identified to characterize the deformation of the tendon between the lines. Force vs. deformation curves were generated for the 5 mm region representing the tendon attachment and the 5 mm region adjacent to the attachment. Stiffness measurements were generated for each curve, and normalized by the initial length to determine the rigidity. The failure strength ranged from 263 N to 548 N, with rigidity values ranging from 2201 N/(mm/mm) to 8714 N/(mm/mm) and from 3459 N/(mm/mm) to 6414 N/(mm/mm) for the attachment and the tendon proximal to the attachment, respectively. The rigidity did not vary significantly between the attachment and proximal tendon based on a Wilcoxon signed rank test (p = 0.2). The measured strength and rigidity establish biomechanical properties for the FDP tendon attachment to bone.

Current Technique for the Ream-and-Run Arthroplasty for Glenohumeral Osteoarthritis.

INTRODUCTION: The ream and run is a technically demanding shoulder arthroplasty for the management of glenohumeral arthritis that avoids the risk of failure of the glenoid component that is associated with total shoulder arthroplasty. STEP 1 SURGICAL APPROACH: After administration of prophylactic antibiotics and a thorough skin preparation, expose the glenohumeral joint through a long deltopectoral incision, incising the subscapularis tendon from its osseous insertion and the capsule from the anterior-inferior aspect of the humeral neck while carefully protecting all muscle groups and neurovascular structures. STEP 2 HUMERAL PREPARATION: Gently expose the proximal part of the humerus, resect the humeral head at 45° to the orthopaedic axis while protecting the rotator cuff, and excise all humeral osteophytes. STEP 3 GLENOID PREPARATION: After performing an extralabral capsular release, remove any residual cartilage, drill the glenoid centerline, and ream the glenoid to a single concavity. STEP 4 HUMERAL PROSTHESIS SELECTION: Select a humeral prosthesis that fits the medullary canal and that provides the desired mobility and stability of the prosthesis. STEP 5 HUMERAL PROSTHESIS FIXATION: Fix the humeral component using impaction autografting. STEP 6 SOFT-TISSUE BALANCING: After the definitive humeral prosthesis is in place, ensure the desired balance of mobility and stability. If there is excessive posterior translation, consider a rotator interval plication. STEP 7 REHABILITATION: Achieve and maintain at least 150° of flexion and good external rotation strength. RESULTS: In our study, comfort and function increased progressively after the ream-and-run procedure, reaching a steady state by approximately twenty months. WHAT TO WATCH FOR: IndicationsContraindicationsPitfalls & Challenges.

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.

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.

Rotator cuff tear associated with a posterior dislocation of the shoulder in a young adult: a case report and literature review.

Posterior glenohumeral dislocations are rare, and an accurate diagnosis is often difficult to make. Although rotator cuff tears are a known risk in the common traumatic anterior glenohumeral dislocation, they are an extremely rare event in association with posterior glenohumeral dislocation, regardless of patient age. There have only been 2 documented cases of rotator cuff tear following posterior shoulder dislocation previously reported in the literature. We report the case of a rotator cuff tear associated with a closed traumatic posterior dislocation of the shoulder in a 22-year-old male involved in a motorcycle accident. This is only the second report of an isolated rotator cuff tear occurring as a result of a posterior shoulder dislocation. Furthermore, this case concerns the youngest patient ever to sustain such an injury in the orthopaedic literature.

Variation in neck-shaft angle: influence in prosthetic design.

Surgeons performing anatomical reconstruction of the shoulder during prosthetic replacement should consider the size of the humeral head and the placement of the head within the humerus. Prosthetic systems with a wide range of modular head sizes, eccentric tapers, and adjustable neck-shaft angles and versions help surgeons to better adapt a prosthesis to a patient's bone anatomy. Surgical technique remains critical for proper placement of the prosthesis and for correction of other soft-tissue and bony abnormalities associated with the pathology. In this article, we review some principles of prosthetic design and surgical technique to anatomically reconstruct the humeral head. We also review the clinical consequences of prosthetic humeral head malpositioning.

Anteroinferior bone-grafting can restore stability in osseous glenoid defects.

BACKGROUND: Glenohumeral instability associated with a large osseous defect of the glenoid can be treated with bone graft to restore the glenoid concavity. The shape and positioning of the graft is critical: a graft that encroaches on the extrapolated glenoid curvature can prevent the head from seating completely in the glenoid, whereas a graft that is too far from the curvature does not restore the glenoid concavity. The purpose of the present study was to investigate how the intrinsic stability that is provided by the glenoid is affected by (1) a standardized anteroinferior glenoid defect and (2) different configurations of anteroinferior glenoid bone graft. METHODS: The anteroinferior stability provided by the glenoid was quantitated by measuring the balance stability angle in that direction. The balance stability angle is the maximal angle that the direction of the net humeral joint-reaction force can make with the glenoid centerline before dislocation takes place. The anteroinferior stability was assessed in each of four fresh-frozen, grossly normal cadaveric glenoids in (1) the unaltered state, (2) after the creation of a standardized defect of a magnitude that has been reported by other investigators to be sufficient to require a bone graft, and (3) after each step of a series of bone-grafting procedures involving grafts of varying height and contour. RESULTS: The anteroinferior glenoid defect significantly diminished the anteroinferior stability by almost 50% (p = 0.006). Bone-grafting significantly increased the stability provided by the glenoid. The increase in stability as compared with that of the glenoid with the standardized defect was particularly marked for contoured graft heights of 6 and 8 mm, for which the increases were 150% (p = 0.0001) and 229% (p < 0.00025), respectively. Contouring of the graft minimized the potential for unwanted contact between the ball and the graft. CONCLUSIONS: Anteroinferior shoulder instability caused by an osseous defect in the glenoid can be corrected with bone-grafting. The effectiveness of the graft in restoring the lost stability is related both to its height and to the extent to which it is contoured as long as the graft is not so prominent that it forces the ball posteriorly from the center of the glenoid.

Impaction grafting improves the fit of uncemented humeral arthroplasty.

This study tested the hypothesis that the excellence of the fit between a humeral prosthesis and the humerus can be optimized by impaction grafting with cancellous bone. Ten paired human humeri were prepared for insertion of a humeral implant by a standard surgical technique. One humerus from each pair was randomized to receive a 10-mm humeral component with cancellous impaction autografting, whereas the other was inserted without grafting. After insertion of a polymethylmethacrylate model of the prosthesis, computed tomography scans were obtained with 3-mm sections and the void areas of each section measured by use of NIH Image. The data demonstrate that cancellous impaction grafting significantly reduces the void between the prosthesis and the humerus (P <.001). The effect was most marked in the proximal and middle thirds of the implant. We conclude that cancellous impaction grafting is an effective method for improving the quality of fit between the humerus and the proximal two thirds of the humeral prosthesis.