Reliability assessment of new radiographic scales to evaluate radiolucency and bony in-between fin growth of partially cemented all-polyethylene glenoid components.

BACKGROUND: Current methods available for assessment of radiolucency and in-between fin (IBF) growth of a glenoid component have not undergone interobserver reliability testing for an all-polyethylene fluted central peg (FCP) glenoid. The purpose of this study was to evaluate anteroposterior radiographs of an FCP glenoid component at ≥48 months comparing commonly used scales to a new method adapted to the FCP. Our hypothesis was that the new method would result in acceptable intra- and interobserver agreement and a more accurate description of radiographic findings. METHODS: We reviewed ≥48-month follow-up radiographs of patients treated with a primary aTSA using an FCP glenoid. Eighty-three patients were included in the review. Radiographs were evaluated by 5 reviewers using novel IBF radiodensity and radiolucency assessments and the Wirth and Lazarus methods. To assess intraobserver reliability, a subset of 40 images was reviewed. Kappa statistics were calculated to determine intra- and interobserver reliability; correlations were assessed using Pearson correlation. RESULTS: Interobserver agreement (κ score) was as follows: IBF 0.71, radiolucency 0.68, Wirth 0.48, and Lazarus 0.22. Intraobserver agreement ranges were as follows: IBF radiodensity 0.36-0.67, radiolucency 0.55-0.62, Wirth 0.11-0.73, and Lazarus 0.04-0.46. Correlation analysis revealed the following: IBF to Wirth r = 0.93, radiolucency to Lazarus r = 0.92 (P value <.001 for all). CONCLUSION: This study introduces a radiographic assessment method developed specifically for an FCP glenoid component. Results show high interobserver and acceptable intraobserver reliability for the method presented in this study. The new scales provide a more accurate description of radiographic findings, helping to identify glenoid components that may be at risk for loosening.

Pyrocarbon hemiarthroplasty of the shoulder: a systematic review and meta-analysis of clinical results.

BACKGROUND: Hemiarthroplasty is often considered in the setting of preserved glenoid cartilage given the high risk of revision associated with total shoulder arthroplasty. Pyrocarbon (PyC) has been used as an implant material that theoretically allows for formation of a neo-membrane that would act like cartilage to reduce glenoid wear. The purpose of this study was to evaluate the clinical outcomes, radiographic outcomes, revision rates, and complication rates in the existing literature on shoulder hemiarthroplasty using PyC. METHODS: The MEDLINE, Embase, and Scopus databases were searched for articles relating to shoulder hemiarthroplasty using the terms "pyrocarbon" or "pyrolytic carbon." Abstracts and articles were screened against predefined inclusion and exclusion criteria, with a minimum of 24 months' follow-up required. Data on patient demographic characteristics, clinical outcome scores, complications, revision rates, and radiographic findings were recorded. Where appropriate, meta-analysis was performed. RESULTS: Twelve studies were selected for final inclusion, with a total of 536 patients. Among the studies reporting preoperative and postoperative range of motion (ROM), an overall improvement in ROM was observed. The mean Constant score was 70.9 points postoperatively, with a mean improvement of 36.2 points (n = 359, 9 studies). Radiographically, 22.8% of patients (n = 536, 8 studies) had evidence of glenoid erosion, 10.4% had changes in implant positioning, and 9.9% had tuberosity thinning. In addition, 1.5% of patients had radiographic subacromial space reduction, whereas 0.7% had an increase in tuberosity thickness. Across all studies, there was an 8.6% complication rate, with the most common cause being glenoid erosion (2.6%, n = 14). There was an overall 7.7% revision rate (n = 41), with 63% of revisions (n = 26) undergoing conversion to reverse or total shoulder arthroplasty. CONCLUSION: PyC hemiarthroplasty shows overall improvements in ROM and patient-reported outcomes for patients. However, there remains concern for glenoid erosion on radiographic evaluation at minimum 2-year follow-up. Although preliminary studies have shown encouraging results, this systematic review emphasizes the need for longer-term follow-up studies with further radiographic evaluation of the severity of glenoid erosion and the association with functional outcomes and failure risk.

Early clinical and radiographic outcomes of anatomic total shoulder arthroplasty with a biconvex posterior augmented glenoid for patients with posterior glenoid erosion: minimum 2-year follow-up.

BACKGROUND: Glenoid bone loss in anatomic total shoulder arthroplasty (aTSA) remains a controversial and challenging clinical problem. Previous studies have shown high rates of glenoid loosening for aTSA in shoulders with retroversion, posterior bone loss, and posterior humeral head subluxation. This study is the first to present minimum 2-year follow-up data of an all-polyethylene, biconvex augmented anatomic glenoid component for correction of glenoid retroversion and posterior humeral head subluxation. METHODS: This study is a multicenter, retrospective review of prospectively collected data on consecutive patients from 7 global clinical sites. All patients underwent aTSA using the biconvex posterior augmented glenoid (PAG). Inclusion criteria were preoperative computed tomographic (CT) scan, minimum 2 years since surgery, preoperative and minimum 2-year postoperative range of motion examination, and patient-reported outcome measures (PROMs). Glenoid classification, glenoid retroversion, and posterior humeral head subluxation were measured from preoperative CT and radiography and postoperative radiography. Statistical comparisons between pre- and postoperative values were performed with a paired t test. RESULTS: Eighty-six of 110 consecutive patients during the study period (78% follow-up) met the inclusion criteria and were included in our analysis. Mean follow-up was 35 ± 10 months, with a mean age of 68 ± 8 years (range 48-85). Range of motion statistically improved in all planes from pre- to postoperation. Mean visual analog scale score improved from 5.2 preoperation to 0.7 postoperation, Single Assessment Numeric Evaluation score from 43.2 to 89.5, Constant score from 41.8 to 76.9, and American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form score from 49.8 to 86.7 (all P < .0001). Mean glenoid retroversion improved from 19.3° to 7.4° (P < .0001). Posterior subluxation improved from 69.1% to 53.5% and posterior decentering improved from 5.8% to -3.0% (P < .0001). There was 1 patient with both a prosthetic joint infection and radiographic glenoid loosening that required revision. Seventy-nine of 86 patients had a Lazarus score of 0 (no radiolucency seen about peg or keel) at final follow-up. CONCLUSIONS: This study shows that at minimum 2-year follow-up, a posterior-augmented all-polyethylene glenoid can correct glenoid retroversion and posterior humeral head subluxation. Clinically, there was significant improvement in both range of motion and PROMs.

Reliability of the modified Walch classification for advanced glenohumeral osteoarthritis using 3-dimensional computed tomography analysis: a study of the ASES B2 Glenoid Multicenter Research Group.

BACKGROUND: Variations in glenoid morphology affect surgical treatment and outcome of advanced glenohumeral osteoarthritis (OA). The purpose of this study was to assess the inter- and intraobserver reliability of the modified Walch classification using 3-dimensional (3D) computed tomography (CT) imaging in a multicenter research group. METHODS: Deidentified preoperative CTs of patients with primary glenohumeral OA undergoing anatomic or reverse total shoulder arthroplasty (TSA) were reviewed with 3D imaging software by 23 experienced shoulder surgeons across 19 institutions. CTs were separated into 2 groups for review: group 1 (96 cases involving all modified Walch classification categories evaluated by 12 readers) and group 2 (98 cases involving posterior glenoid deformity categories [B2, B3, C1, C2] evaluated by 11 readers other than the first 12). Each case group was reviewed by the same set of readers 4 different times (with and without the glenoid vault model present), blindly and in random order. Inter- and intraobserver reliabilities were calculated to assess agreement (slight, fair, moderate, substantial, almost perfect) within groups and by modified Walch classification categories. RESULTS: Interobserver reliability showed fair to moderate agreement for both groups. Group 1 had a kappa of 0.43 (95% confidence interval [CI]: 0.38, 0.48) with the glenoid vault model absent and 0.41 (95% CI: 0.37, 0.46) with it present. Group 2 had a kappa of 0.38 (95% CI: 0.33, 0.43) with the glenoid vault model absent and 0.37 (95% CI: 0.32, 0.43) with it present. Intraobserver reliability showed substantial agreement for group 1 with (0.63, range 0.47-0.71) and without (0.61, range 0.52-0.69) the glenoid vault model present. For group 2, intraobserver reliability showed moderate agreement with the glenoid vault model absent (0.51, range 0.30-0.72), which improved to substantial agreement with the glenoid vault model present (0.61, range 0.34-0.87). DISCUSSION: Inter- and intraobserver reliability of the modified Walch classification were fair to moderate and moderate to substantial, respectively, using standardized 3D CT imaging analysis in a large multicenter study. The findings potentially suggest that cases with a spectrum of posterior glenoid bone loss and/or dysplasia can be harder to distinguish by modified Walch type because of a lack of defined thresholds, and the glenoid vault model may be beneficial in determining Walch type in certain scenarios. The ability to reproducibly separate patients into groups based on preoperative pathology, including Walch type, is important for future studies to accurately evaluate postoperative outcomes in TSA patient cohorts.

Anatomic evaluation of radiographic landmarks for accurate straight antegrade intramedullary nail placement in the humerus.

BACKGROUND: Neurovascular insult, nonunion, and iatrogenic rotator cuff injury are concerns when using an intramedullary nail (IMN) for proximal humerus fracture. The purpose of this study was to identify a reproducible starting point and intraoperative imaging for nail insertion optimizing nail depth, tuberosity screw position, and protecting the axillary nerve and rotator cuff insertion. Our hypothesis was that a more medialized starting point would protect soft tissue structures and improve locking screw positioning. METHODS: Ten fresh-frozen cadavers underwent antegrade IMN with Grashey and modified lateral "precipice" view imaging. A guidewire was positioned medial to the coracoacromial ligament (CAL) in 5 cadavers and lateral to the CAL in 5. Distances from the nail entry point to anatomic landmarks were measured. Anatomic and histologic evaluations were performed, characterizing the nail perforation zone. Radiographs were compared between groups. RESULTS: The medial CAL group had a greater distance of screw fixation to the axillary nerve, a shorter distance of greater tuberosity (GT) screw fixation at the rotator cuff insertion on the infraspinatus and teres minor tubercles, and greater screw spread with improved lesser tuberosity capture. Two laterally placed implants violated the rotator cuff tendon. Imaging demonstrated that the ideal starting pin position was medial to the articular margin at a distance equal to the width of the rotator cuff insertion footprint. CONCLUSIONS: Medial placement optimized fixation of the GT, avoided violation of the rotator cuff tendon and footprint, and was associated with an increased distance of proximal locking screw to the axillary nerve.

Osseous changes following reverse total shoulder arthroplasty combined with latissimus dorsi transfer: a case series.

BACKGROUND: This is the first report on the incidence of proximal humerus osseous changes and associated clinical consequences in reverse total shoulder arthroplasty combined with a latissimus dorsi tendon transfer (RTSA+LDT). METHODS: A multicenter, retrospective review identified all patients who had undergone a primary RTSA+LDT and had at least 3-month radiographic follow-up between 2012 and 2017. Data collection included demographics, oral steroid use, repair technique for LDT fixation, radiographic humeral osseous changes, complications, and need for revision surgery. RESULTS: Twenty-four patients were included with an average age of 70.7 ± 7.9 years and follow-up of 16.3 (3-50) months. Ten patients (41.7%) developed osseous changes at the transfer location. There was no increased risk of developing osseous changes based on the surgical fixation technique (P = .421). Average time to earliest radiographic detection of osseous changes was 2.7 ± 1.7 months, with all changes occurring at or before 6 months. Two patients developed proximal humerus fractures, of which 1 had osseous changes through which the fracture occurred. DISCUSSION: RTSA+LDT may place the proximal humeral cortex at greater risk than previously described. Using a long-stem prosthesis in the setting of RTSA+LDT may limit the consequences of this complication.

The relationship of shoulder elevation strength to patient-reported outcome after anatomic total shoulder arthroplasty.

BACKGROUND: Most patient-reported outcome measures (PROMs) used to assess outcomes after anatomic total shoulder arthroplasty (aTSA) focus on pain and function. Although strength is considered an important component of function, only the Constant-Murley score (CMS) includes an objective measurement of shoulder strength. The purpose of this study was to evaluate the relationship between shoulder elevation strength (SES) and PROMs after aTSA for the treatment of primary glenohumeral osteoarthritis (GHOA). METHODS: This was a retrospective analysis of 605 patients enrolled in a multicenter clinical database who underwent aTSA to treat primary GHOA. Patients were evaluated preoperatively and at 24 months after surgery. Outcome was assessed with the CMS, American Shoulder and Elbow Surgeons score, Western Ontario Osteoarthritis of the Shoulder score, Single Assessment Numeric Evaluation score, and patient satisfaction. Relationships between SES and outcomes were investigated. RESULTS: The correlations between SES and the PROMs before and after treatment were very weak and weak, respectively (r ≤ 0.262 for all). The strength of the correlations between the absolute and adjusted CMS and the other PROMs varied from weak to moderate (r = 0.180 to r = 0.455), and the strength of the correlations was greater postoperatively. With the strength component removed from the CMS, the correlations between the CMS and other PROMs were stronger (r = 0.194 to r = 0.495). CONCLUSIONS: Although measurement of SES provides objective information about shoulder function and outcome related to the treatment of primary GHOA with aTSA, the actual relevance to patients is unclear as the correlations between SES and PROMs were weak. Furthermore, the variable correlations between the CMS and PROMs call into question the exclusive use of the CMS and support the use of other PROMs that may more accurately reflect patient perception of outcome.

Intramedullary Fixation for Proximal Humeral Fractures.

Proximal humeral fractures are a commonly encountered injury; however, no consensus has been reached for the ideal treatment. Current surgical fixation options include plate, plate with fibular strut allograft, intramedullary fixation, pinning, suture constructs, and external fixation. Each of these options possesses distinct advantages and disadvantages. With the evolution of implant design, a greater understanding of the mechanisms of failure of fixation, and the ability to preserve fracture biology, the management of proximal humeral fractures with intramedullary fixation has become an accepted treatment option. From a biomechanical perspective, intramedullary fixation may have advantages over laterally based fixation, in particular with fractures associated with significant calcar comminution. The ability to insert the implant from a superior starting point may help preserve vascular supply to the humeral head and tuberosities. With reported outcomes comparable with the aforementioned techniques and an evolving understanding of fracture characteristics and failures of fixation, intramedullary fixation represents an alternative treatment option for proximal humeral fractures with specific fixation and biologic advantages.

Displaced humeral surgical neck fractures: classification and results of third-generation percutaneous intramedullary nailing.

BACKGROUND: The high rates of complications and reoperations observed with the early designs of first-generation (unlocked) and second-generation (bent design) humeral intramedullary nail (IMNs) have discouraged their use by most surgeons. The purpose of this study was to report the results of a third-generation (straight, locking, low-profile, tuberosity-based fixation) IMN, inserted through a percutaneous approach, for the treatment of displaced 2-part surgical neck fractures. METHODS: We performed a retrospective review of 41 patients who underwent placement of a third-generation IMN to treat a displaced 2-part surgical neck fracture (AO/OTA type 11A3). The mean age at surgery was 57 years (range, 17-84 years). After percutaneous insertion through the humeral head, the IMN was used as a reduction tool. Static locking fixation was achieved after axial fracture compression ("back-slap" hammering technique). Patients were reviewed and underwent radiography with a minimum of 1 year of follow-up; the mean follow-up period was 26 months (range, 12-53 months). RESULTS: Preoperatively, 3 types of surgical neck fractures were observed: with valgus head deformity (Type A = 8 cases), shaft translation without head deformity (Type B = 19 cases), or with varus head deformity (Type C = 14 cases). At final follow-up, all fractures went on to union, and the mean humeral neck-shaft angle was 132° ± 5°. We observed 2 malunions and 1 case of partial humeral head avascular necrosis. No cases underwent screw migration or intra-articular penetration. At last review, mean active forward elevation was 146° (range, 90°-180°) and mean external rotation was 50° (range, 20°-80°). The mean Constant-Murley score and Subjective Shoulder Value were 71 (range, 43-95) and 80% (range, 50%-100%), respectively. CONCLUSIONS: Antegrade insertion of a third-generation IMN through a percutaneous approach provides a high rate of fracture healing, excellent clinical outcome scores, and a low rate of complications. No morbidity related to the passage of the nail through the supraspinatus muscle and the cartilage was observed. The proposed A, B, and C classification allows choosing the optimal entry point for intramedullary nailing.

Traumatic Divergent Elbow Dislocation with Associated Forearm Amputation in an Adult: A Case Report.

CASE: A 49-year-old right-hand-dominant man sustained an auger-related injury that resulted in open dislocation at the left wrist and palm, with complete amputation of the distal aspect of the forearm and the hand. The injury at the elbow included instability with an ulnar coronoid fracture, posterior dislocation of the ulna, and posterolateral dislocation of the radius. To restore stability of the forearm stump and elbow, we performed a complete resection of the radius, open reduction and internal fixation of the coronoid tip, a repair of the lateral collateral ligament, and transfer of the distal biceps tendon to the coronoid. CONCLUSION: The procedure stabilized the elbow, allowing for early mobilization. The patient was eventually fitted with a prosthesis that allowed him to return to full-time manual labor in a rural setting.

Intramedullary nailing of the proximal humerus: evolution, technique, and results.

Proximal humerus fractures are the third most common fracture in the elderly. Although most fractures can be treated conservatively with acceptable outcomes, certain fracture patterns are at high risk for progression to humeral malunions, nonunions, stiffness, and post-traumatic arthrosis. The goal of antegrade humeral nailing of proximal humerus fractures is to provide stability to a reduced fracture that allows early motion to optimize patient outcomes. Certain technical pearls are pivotal in managing these difficult fractures with nails; these include rotator cuff management, respect of the soft tissues, anatomic tuberosity position, blood supply maintenance, knowledge of the deforming forces on the proximal humerus, fracture reduction, and rehabilitation strategies. Modern proximal humeral nail designs and techniques assist the surgeon in adhering to these principles and have demonstrated promising outcomes. Humeral nail designs have undergone significant innovation during the past 40 years and now can provide stable fixation in the humeral shaft distally as well as improved stability in the head and tuberosity fragments, which were the common site of fixation failure with earlier generation implants. Compared with other fixation strategies, such as locking plate fixation, no compelling evidence exists to suggest one technique over another. The purpose of this review is to describe the history, results, new designs, and techniques that make modern intramedullary nailing of proximal humerus fractures a viable treatment option.

Complex trauma to the shoulder girdle, including the proximal humerus, the clavicle, and the scapula: current concepts in diagnosis and treatment.

Fractures to the shoulder girdle are common injuries in an aging population. Many techniques and theories lie behind the treatment of such injuries. Knowledge and understanding of current concepts for diagnosing and treating proximal humeral, clavicular, and scapular fractures and the theory behind them will help surgeons make informed decisions with regard to patient care.

Angular-stable locked intramedullary nailing of two-part surgical neck fractures of the proximal part of the humerus. A multicenter retrospective observational study.

BACKGROUND: The ideal fixation technique for the treatment of proximal humeral fractures remains unclear. In the present study, we evaluated the experience of three surgeons with the treatment of two-part surgical neck fractures with angular-stable intramedullary fixation. METHODS: Forty-eight patients with forty-eight Neer two-part surgical neck proximal humeral fractures were managed with locked angular-stable intramedullary nail fixation by three surgeons. Shoulder pain and outcomes were quantified with Constant scores and standard radiographs. RESULTS: Thirty-eight patients (including twenty-eight female patients and ten male patients) with a mean age of sixty-five years were followed for at least twelve months (mean, twenty months; range, twelve to thirty-six months). All fractures healed primarily. The mean follow-up Constant score (and standard deviation) was 71 ± 12 points (range, 37 to 88 points), with a mean age-adjusted Constant score of 97% (range, 58% to 119%). The mean Constant pain score was 13 ± 2.2 (possible range, 0 to 15 points, with 15 points representing no pain). The mean forward flexion was 132° ± 22°. All fractures but one healed with a neck-shaft angle of ≥125°. CONCLUSIONS: Patients who were managed with locked angular-stable intramedullary nailing of two-part surgical neck proximal humeral fractures via an articular entry point had reliable fracture-healing, favorable clinical outcomes, and little residual shoulder pain.

Neer Award 2005: The Grammont reverse shoulder prosthesis: results in cuff tear arthritis, fracture sequelae, and revision arthroplasty.

This clinical study was performed to analyze the midterm results and potential complications of the reverse prosthesis in different diagnosis. Forty-five consecutive patients with Grammont prosthesis were evaluated clinically and radiographically with a mean follow-up of 40 months (range, 24-72 months). The indication was a massive and irreparable cuff tear associated with arthrosis (CTA) in 21 cases, fracture sequelae (FS) with arthritis in 5 cases, and failure of a revision arthroplasty (revision) in 19 cases. Fourteen complications occurred in 11 patients. 3 dislocations, 3 deep infections (all 3 in the revision group), 1 case of aseptic humeral loosening, 2 periprosthetic humeral fractures, 1 intraoperative glenoid fracture, 1 wound hematoma, 2 late acromial fractures, and 1 axillary nerve palsy. Of the patients, 10 (22%) required further surgery: 4 reoperations, 4 prosthesis revisions, and 2 prosthesis removals. Complications were higher in revision than in CTA (47% vs. 5%). All 3 groups showed a significant increase in active elevation (from 55 degrees preoperatively to 121 degrees postoperatively) and Constant score (from 17 to 58 points) but no significant change in active external rotation (from 7 degrees to 11 degrees ) or internal rotation (S1 preoperatively and postoperatively). Of the patients, 78% were satisfied or very satisfied with the result and 67% had no or slight pain. However, the postoperative Constant score, adjusted Constant score, and American Shoulder and Elbow Surgeons shoulder score were all significantly higher in the CTA group with as compared with the revision group (P = .01, .004, and .002, respectively). Scapular notching was seen in 24 cases (68%). No glenoid loosening was observed at current follow-up, even when the notch extended beyond the inferior screw (28% of cases). Atrophy of severe fatty infiltration of the teres minor was associated with lower external rotation (15 degrees vs 0 degrees , P = .02) and lower functional results (Constant score of 46 points vs 66 points, P < .007). The Grammont reverse prosthesis can improve function and restore active elevation in patients with incongruent cuff-deficient shoulders; active rotation is usually unchanged. Results are less predictable and complication and revision rates are higher in patients undergoing revision surgery as compared with those in patients with CTA. Results of the reverse prosthesis depend on the diagnosis and on the remaining cuff muscles, specifically the teres minor. Surgeons should be vigilant with regard to low-grade infection in revision surgery.

Arthroscopic repair of full-thickness tears of the supraspinatus: does the tendon really heal?

BACKGROUND: Good functional results have been reported for arthroscopic repair of rotator cuff tears, but the rate of tendon-to-bone healing is still unknown. Our hypothesis was that arthroscopic repair of full-thickness supraspinatus tears achieves a rate of complete tendon healing equivalent to those reported in the literature with open or mini-open techniques. METHODS: Sixty-five consecutive shoulders with a chronic full-thickness supraspinatus tear were repaired arthroscopically in sixty-five patients with use of a tension-band suture technique. Patients ranged in age from twenty-nine to seventy-nine years. The average duration of follow-up was twenty-nine months. Fifty-one patients (fifty-one shoulders) had a computed tomographic arthrogram, and fourteen had a magnetic resonance imaging scan, performed between six months and three years after surgery. All patients were assessed with regard to function and the strength of the shoulder elevation. RESULTS: The rotator cuff was completely healed and watertight in forty-six (71%) of the sixty-five patients and was partially healed in three. Although the supraspinatus tendon did not heal to the tuberosity in sixteen shoulders, the size of the persistent defect was smaller than the initial tear in fifteen. Sixty-two of the sixty-five patients were satisfied with the result. The Constant score improved from an average (and standard deviation) of 51.6 +/- 10.6 points preoperatively to 83.8 +/- 10.3 points at the time of the last follow-up evaluation (p < 0.001), and the average University of California at Los Angeles score improved from 11.5 +/- 1.1 to 32.3 +/- 1.3 (p < 0.001). The average strength of the shoulder elevation was significantly better (p = 0.001) when the tendon had healed (7.3 +/- 2.9 kg) than when it had not (4.7 +/- 1.9 kg). Factors that were negatively associated with tendon healing were increasing age and associated delamination of the subscapularis or infraspinatus tendon. Only ten (43%) of twenty-three patients over the age of sixty-five years had completely healed tendons (p < 0.001). CONCLUSIONS: Arthroscopic repair of an isolated supraspinatus detachment commonly leads to complete tendon healing. The absence of healing of the repaired rotator cuff is associated with inferior strength. Patients over the age of sixty-five years (p = 0.001) and patients with associated delamination of the subscapularis and/or the infraspinatus (p = 0.02) have significantly lower rates of healing.

Grammont reverse prosthesis: design, rationale, and biomechanics.

Combined destruction of the rotator cuff and the glenohumeral joint may lead to a painful and pseudo-paralyzed shoulder. In this situation a nonconstrained shoulder prosthesis yields a limited functional result or may even be contraindicated. Previous constrained prostheses (ball-and-socket or reverse ball-and-socket designs) have failed because their center of rotation remained lateral to the scapula, which limited motion and produced excessive torque on the glenoid component, leading to early loosening. The reverse prosthesis designed by Paul Grammont, unlike any previous reverse ball-and-socket design, has introduced 2 major innovations that have led to its success: (1) a large glenoid hemisphere with no neck and (2) a small humeral cup almost horizontally oriented with a nonanatomic inclination of 155 degrees, covering less than half of the glenosphere. This design medializes and stabilizes the center of rotation, minimizes torque on the glenoid component, and helps in recruiting more fibers of the anterior and posterior deltoid to act as abductors. Furthermore, the humerus is lowered relative to the acromion, restoring and even increasing deltoid tension. The Grammont reverse prosthesis imposes a new biomechanical environment for the deltoid muscle to act, thus allowing it to compensate for the deficient rotator cuff muscles. The clinical experience does live up to the biomechanical concept: the reverse prosthesis restores active elevation above 90 degrees in patients with a cuff-deficient shoulder. However, external rotation often remains limited, particularly in patients with an absent or fat-infiltrated teres minor. Internal rotation is also rarely restored after a reverse prosthesis. Failure to restore sufficient tension in the deltoid may result in prosthetic instability. The design does appear to protect against early loosening of the glenoid component, but impingement of the humeral cup on the scapular neck can lead to scapular notching and polyethylene wear. This is a cause for concern, especially as the notch is often more extensive than can be explained by impingement alone. Bony lysis of the scapula may also be related to a polyethylene granuloma. Further follow-up is required to ensure that loosening does not become a problem in the long term, and it has been recommended to limit its use to elderly patients, arguably those aged over 70 years. Despite these concerns, the reverse prosthesis, based on the biomechanical Grammont concept, offers a true surgical option in several situations where only limited possibilities were previously available: cuff tear arthrosis, persistent shoulder pseudo-paralysis due to a massive and irreparable cuff tear, severe fracture sequelae, prosthetic revision in a cuff-deficient shoulder, and tumor surgery. Finally, surgeons must be aware that results are less predictable and complication/revision rates are higher in revision surgery.

Entrapment of the long head of the biceps tendon: the hourglass biceps--a cause of pain and locking of the shoulder.

We describe an unrecognized mechanical condition affecting the long head of the biceps (LHB) tendon with entrapment of the tendon within the joint and subsequent pain and locking of the shoulder on elevation of the arm. We identified 21 patients with a hypertrophic intraarticular portion of the LHB tendon during open surgery (14 patients) or arthroscopic surgery (7 patients). All cases but one were associated with a rotator cuff rupture. Patients were treated by biceps tenotomy (2 patients) or tenodesis (19 patients) after removal of the hypertrophic intraarticular portion of the tendon and appropriate treatment of concomitant lesions. Minimum follow-up was 1 year. All patients presented with anterior shoulder pain and loss of active and passive elevation averaging 10 degrees to 20 degrees. A dynamic intraoperative test, involving forward elevation with the elbow extended, demonstrated entrapment of the tendon within the joint in each case. This test creates a characteristic buckling of the tendon and squeezing of it between the humeral head and the glenoid (hourglass test). The mean Constant score improved from 38 to 76 points at the final follow-up (P <.05). Complete and symmetric elevation was restored in all cases after resection of the intraarticular portion of the LHB tendon. The hourglass biceps is caused by a hypertrophic intraarticular portion of the tendon that is unable to slide into the bicipital groove during elevation of the arm; it can be compared with the condition of trigger finger in the hand. A loss of 10 degrees to 20 degrees of passive elevation, bicipital groove tenderness, and radiographic findings of a hypertrophied tendon can aid in the diagnosis. A definitive diagnosis is made at surgery with the hourglass test: incarceration and squeezing of the tendon within the joint during forward elevation of the arm with the elbow extended. The hourglass biceps is responsible for a mechanical block, which is similar to a locked knee with a bucket-handle meniscal tear. Simple tenotomy cannot resolve this mechanical block. Excision of the intraarticular portion of the LHB tendon, during bipolar biceps tenotomy or tenodesis, must be performed. The hourglass biceps is an addition to the familiar pathologies of the LHB (tenosynovitis, prerupture, rupture, and instability) and should be considered in cases of shoulder pain associated with a loss of elevation.