Platform shoulder arthroplasty: a systematic review.

BACKGROUND: Platform shoulder arthroplasty systems may allow conversion to a reverse total shoulder arthroplasty (RTSA) without removing a well-fixed, well-positioned humeral stem. We sought to evaluate the complications associated with humeral stem exchange versus retention in patients undergoing conversion shoulder arthroplasty with a platform shoulder arthroplasty system. METHODS: PubMed, MEDLINE, CINAHL (Cumulative Index to Nursing and Allied Health Literature), and Embase were searched from database inception through October 9, 2016, for all articles comparing humeral stem retention versus exchange during conversion RTSA or that pertained to conversion RTSA with stem retention alone. All studies were screened in duplicate for eligibility. A methodologic quality assessment was completed for included studies. Pooled outcomes assessing complications, operative time, blood loss, and reoperations were determined. RESULTS: We included 7 studies (236 shoulders), including 1 level III and 6 level IV studies. Pooled analysis demonstrated significantly higher overall complications (odds ratio, 6.89; 95% confidence interval [CI], 2.48-19.13; P = .0002), fractures (odds ratio, 4.62; 95% CI, 1.14-18.67; P = .03), operative time (mean difference, 62.09 minutes; 95% CI, 51.17-73.01 minutes; P < .00001), and blood loss (mean difference, 260.06 mL; 95% CI, 165.30-354.83 mL; P < .00001) with humeral stem exchange. Stem exchange was also associated with increased risk of reoperation (P = .0437). CONCLUSION: Conversion arthroplasty with retention of the humeral stem is associated with lower overall complications, blood loss, operative time, and reoperations in comparison with stem exchange.

Biomechanical Evaluation of All-Polyethylene Pegged Bony Ingrowth Glenoid Fixation Techniques on Implant Micromotion.

Newer glenoid components that allow for hybrid cement fixation via traditional cementation of peripheral pegs and bony ingrowth into an interference-fit central peg introduce the possibility of long-term biological fixation. However, little biomechanical work has been done on the initial stability of these components and the various fixation options. We conducted a study in which all-polyethylene glenoid components with a centrally fluted peg were implanted in polyurethane blocks with interference-fit, hybrid cement, and fully cemented fixation (5 per fixation group). Biomechanical evaluation of glenoid loosening, according to ASTM Standard F-2028-12, subjected the glenoids to 50,000 cycles of rim loading, and glenoid component motion was recorded with 2 differential variable reluctance transducers fixed to each glenoid prosthesis. Fully cemented fixation exhibited significantly less mean distraction in comparison with interference-fit fixation (P < .001) and hybrid cement fixation (P < .001). Hybrid cement fixation exhibited significantly less distraction (P < .001), more compression (P < .001), and no significant difference in glenoid translation (P = .793) in comparison with interference-fit fixation. Fully cemented fixation exhibited the most resistance to glenoid motion in comparison with hybrid cement fixation and interference-fit fixation. However, hybrid cement fixation and interference-fit fixation exhibited equivocal motion. Given these results, cementation of peripheral pegs may confer no additional initial stability over that provided by uncemented interference-fit fixation.

The impact of rotator cuff deficiency on structure, mechanical properties, and gene expression profiles of the long head of the biceps tendon (LHBT): Implications for management of the LHBT during primary shoulder arthroplasty.

The long head of the biceps tendon (LHBT) occupies a unique proximal intra-articular and distal extra-articular position within the human shoulder. In the presence of a rotator cuff (RC) tear, the LHBT is recruited into an accelerated role undergoing potential mechanical and biochemical degeneration. Intra-articular sections of the LHBT were harvested during primary shoulder arthroplasty from patients with an intact or deficient RC. LHBTs were stained (H&E, Alcian Blue) and subjected to histologic analysis using the semiquantitative Bonar scale and measurement of collagen orientation. LHBTs (n = 12 per group) were also subjected to gene-expression analyses via an RT(2) -PCR Profiler Array quantifying 84 genes associated with cell-cell and cell-matrix interactions. LHBTs (n = 18 per group) were biomechanically tested with both stress-relaxation and load-to-failure protocols and subsequently modeled with the Quasilinear Viscoelastic (QLV) and Structural-Based Elastic (SBE) models. While no histologic differences were observed, significant differences in mechanical testing, and viscoelastic modeling parameters were found. PCR arrays identified five genes that were differentially expressed between RC-intact and RC-deficient LHBT groups. LHBTs display signs of pathology regardless of RC status in the arthroplasty population, which may be secondary to both glenohumeral joint arthritis and the additional mechanical role of the LHBT in this population.

Preoperative deltoid size and fatty infiltration of the deltoid and rotator cuff correlate to outcomes after reverse total shoulder arthroplasty.

BACKGROUND: Reverse total shoulder arthroplasty (RTSA) allows the deltoid to substitute for the nonfunctioning rotator cuff. To date, it is unknown whether preoperative deltoid and rotator cuff parameters correlate with clinical outcomes. QUESTIONS/PURPOSES: We asked whether associations exist between 2-year postoperative results (ROM, strength, and outcomes scores) and preoperative (1) deltoid size; (2) fatty infiltration of the deltoid; and/or (3) fatty infiltration of the rotator cuff. METHODS: A prospective RTSA registry was reviewed for patients with cuff tear arthropathy or massive rotator cuff tears, minimum 2-year followup, and preoperative shoulder MRI. Final analysis included 30 patients (average age, 71±10 years; eight males, 22 females). Only a small proportion of patients who received an RTSA at our center met inclusion and minimum followup requirements (30 of 222; 14%); however, these patients were found to be similar at baseline to the overall group of patients who underwent surgery in terms of age, gender, and preoperative outcomes scores. The cross-sectional area of the anterior, middle, and posterior deltoid was measured on axial proton density-weighted MRI. Fatty infiltration of the deltoid, supraspinatus, infraspinatus, teres minor, and subscapularis were quantitatively assessed on sagittal T1-weighted MR images. Patients were followed for Constant-Murley score, American Shoulder and Elbow Surgeons (ASES) scores, subjective shoulder value, pain, ROM, and strength. Correlations of muscle parameters with all outcomes measures were calculated. RESULTS: Preoperative deltoid size correlated positively with postoperative Constant-Murley score (67.27±13.07) (ρ=0.432, p=0.017), ASES (82.64±14.25) (ρ=0.377; p=0.40), subjective shoulder value (82.67±17.89) (ρ=0.427; p=0.019), and strength (3.72 pounds±2.99 pounds) (ρ=0.454; p=0.015). Quantitative deltoid fatty infiltration (7.91%±4.32%) correlated with decreased postoperative ASES scores (ρ=-0.401; p=0.047). Quantitative fatty infiltration of the infraspinatus (30.47%±15.01%) correlated with decreased postoperative external rotation (34.13°±16.80°) (ρ=-0.494; p=0.037). CONCLUSIONS: Larger preoperative deltoid size correlates with improved validated outcomes scores, whereas fatty infiltration of the deltoid and infraspinatus may have deleterious effects on validated outcomes scores and ROM after RTSA. The current study is a preliminary exploration of this topic; future studies should include prospective enrollment and standardized MRI with a multivariate statistical approach. Quantitative information attained from preoperative imaging not only holds diagnostic value, but, should future studies confirm our findings, also might provide prognostic value. This information may prove beneficial in preoperative patient counseling and might aid preoperative and postoperative decision-making by identifying subpopulations of patients who may benefit by therapy aimed at improving muscle properties. LEVEL OF EVIDENCE: Level III, prognostic study.

Wear rates of highly cross-linked polyethylene humeral liners subjected to alternating cycles of glenohumeral flexion and abduction.

BACKGROUND: Although short-term outcomes of reverse total shoulder arthroplasty have been promising, long-term success may be limited due to device-specific complications, including scapular notching. Scapular notching has been explained primarily as mechanical erosion; however, the generation of wear debris may lead to further biologic changes contributing to the severity of scapular notching. METHODS: A 12-station hip simulator was converted to a reverse total shoulder arthroplasty wear simulator subjecting conventional and highly cross-linked ultra-high-molecular-weight polyethylene humeral liners to 5 million cycles of alternating abduction-adduction and flexion-extension loading profiles. RESULTS: Highly cross-linked polyethylene liners (36.5 ± 10.0 mm(3)/million cycle) exhibited significantly lower volumetric wear rates compared with conventional polyethylene liners (83.6 ± 20.6 mm(3)/million cycle; P < .001). The flexion-extension loading profile exhibited significantly higher wear rates for conventional (P < .001) and highly cross-linked polyethylene (P < .001) compared with the abduction-adduction loading profile. Highly cross-linked wear particles had an equivalent circle diameter significantly smaller than wear particles from conventional polyethylene (P < .001). CONCLUSIONS: Highly cross-linked polyethylene liners significantly reduced polyethylene wear and subsequent particle generation. More favorable wear properties with the use of highly cross-linked polyethylene may lead to increased device longevity and fewer complications but must be weighed against the effect of reduced mechanical properties.

The evaluation of the failed shoulder arthroplasty.

As the incidence of shoulder arthroplasty continues to rise, the orthopedic shoulder surgeon will be increasingly faced with the difficult problem of evaluating a failed shoulder arthroplasty. The patient is usually dissatisfied with the outcome of the previous arthroplasty as a result of pain, but may complain of poor function due to limited range of motion or instability. A thorough and systematic approach is necessary so that the most appropriate treatment pathway can be initiated. A comprehensive history and physical examination are the first steps in the evaluation. Diagnostic studies are numerous and include laboratory values, plain radiography, computed tomography, ultrasound imaging, joint aspiration, nuclear scans, and electromyography. Common causes of early pain after shoulder arthroplasty include technical issues related to the surgery, such as malposition or improper sizing of the prosthesis, periprosthetic infection, neurologic injury, and complex regional pain syndrome. Pain presenting after a symptom-free interval may be related to chronic periprosthetic infection, component wear and loosening, glenoid erosion, rotator cuff degeneration, and fracture. Poor range of motion may result from inadequate postoperative rehabilitation, implant-related factors, and heterotopic ossification. Instability is generally caused by rotator cuff deficiency and implant-related factors. Unfortunately, determining the cause of a failed shoulder arthroplasty can be difficult, and in many situations, the source of pain and disability is multifactorial.

Clinical and radiographic results of cementless reverse total shoulder arthroplasty: a comparative study with 2 to 5 years of follow-up.

BACKGROUND: Most studies of reverse total shoulder arthroplasty (RTSA) involve cemented humeral stems. To our knowledge, this is the first study to compare the results of cementless RTSA, using a porous-coated stem designed for uncemented fixation, with cemented RTSA. METHODS: A prospective database of patients undergoing RTSA was retrospectively reviewed for patients with a diagnosis of cuff tear arthropathy or severe rotator cuff deficiency with minimum 2-year follow-up. Of these, 37 patients had cemented RTSA and 64 patients had cementless RTSA. Outcome measures included Constant-Murley scores, American Shoulder and Elbow Surgeons scores, visual analog pain scale scores, range of motion, patient satisfaction, and radiographic evidence of complication. RESULTS: Compared with preoperative values, both cohorts demonstrated significant improvements (P < .01) in all functional scores, active forward elevation, and active internal rotation. There was no significant difference (P > .05) in comparing the changes in these values after surgery between the cemented and cementless cohorts. On radiographic evaluation, there was no evidence of loosening or humeral components "at risk" of loosening in either group. There was no significant difference (P = 1.0) in the incidence of humeral component radiolucent lines between the cemented and uncemented cohorts. There was no significant difference (P = .30) in the incidence of scapular notching between the cemented (n = 8) and uncemented (n = 10) cohorts. CONCLUSION: Cementless fixation of a porous-coated RTSA humeral stem provides clinical and radiographic outcomes equivalent to those of cemented stems at minimum 2-year follow-up. With advantages such as simplified operative technique, no cement-related complications, greater ease of revision, and long-lasting biologic fixation, uncemented fixation may provide several benefits over cemented fixation.

Biomechanical testing of small versus large lesser tuberosity osteotomies: effect on gap formation and ultimate failure load.

BACKGROUND: Subscapularis muscle dysfunction after total shoulder arthroplasty (TSA) can be a devastating complication. Recent biomechanical and clinical results suggest the superiority of lesser tuberosity osteotomy (LTO) over subscapularis tenotomy; however, disagreement over the best repair technique remains. This study aimed to characterize the strength of 2 novel repair techniques for LTO fixation compared with standard tenotomy and dual-row tuberosity osteotomies during TSA. METHODS: Twenty fresh frozen cadaveric shoulders were dissected of all soft tissues except the humeri and attached subscapularis myotendinous unit. Humeri and subscapularis muscle belly were secured to a materials testing frame and subjected to cyclic loading, followed by load to failure for characterization of gap formation, ultimate failure load, and mechanism of failure. Repair techniques investigated were traditional subscapularis tenotomy and dual-row fleck LTO compared with novel techniques of single-cable and 2-suture large LTO repairs. RESULTS: No significant difference in ultimate failure load was noted among the repair techniques (P = .565). The tenotomy repair (6.0 ± 3.9 mm) displayed significantly greater gapping in response to increasing load than LTO repair techniques (P < .05). No significant difference was noted between any LTO repairs at specific loads during cyclic testing (P > .05). CONCLUSION: Our study displayed superior repair integrity of LTO vs tenotomy repairs. The advantages of the 2-suture large LTO technique over other LTO techniques include its simple technique, with a minimum amount of suture, avoidance of metallic hardware, and greater access to the glenoid, while providing comparable repair stability. Further research is warranted to fully evaluate these new techniques.

Reverse total shoulder arthroplasty for the management of failed shoulder arthroplasty with proximal humeral bone loss: is allograft augmentation necessary?

BACKGROUND: Patients undergoing revision shoulder arthroplasty frequently have deficient proximal humeral bone stock. Proximal humeral allograft has been recommended to augment reverse total shoulder arthroplasty (RTSA) to improve stability and function. This study reports the results of RTSA without proximal humeral allograft in patients with proximal humeral bone loss secondary to failed shoulder arthroplasty. MATERIALS AND METHODS: From 2005 to 2008, 251 patients were enrolled in a prospective RTSA cohort study. Significant humeral bone loss was demonstrated in 15 of 56 undergoing revision for failed arthroplasty. Average age was 67 years. Average bone loss measured 38.4 mm (range, 26-72 mm). Patients were followed up for a minimum of 2 years with American Shoulder and Elbow Surgeons (ASES), Subjective Shoulder Value (SSV), Constant Score (CS), and visual analog scale (VAS) pain scores, as well as self-reported satisfaction and radiographs. RESULTS: Patients demonstrated significant improvement in mean CS (23.0 to 44.2), ASES (38.2 to 68.3), ASES activities of daily living (7.0 to 15.9), SSV (19.2 to 75.8), and VAS pain (4.6 to 1.6) scores. Thirteen of 15 patients reported satisfaction (87%). Range of motion improved in forward flexion (38.3° to 103.2°) and external rotation (-0.5° to 11.9°). Radiographs demonstrated notching in 3 patients (20%), no humeral subsidence or loosening, and prosthetic fracture of 1 modular humeral stem. CONCLUSIONS: Use of RTSA for failed shoulder arthroplasty and deficient humeral bone stock provides a significant clinical benefit without the need for allograft augmentation. Monoblock humeral component use may diminish risk for prosthetic fracture.

Meniscus tears in the young athlete: results of arthroscopic repair.

BACKGROUND: The purpose of this study was to evaluate the results of arthroscopic repair of the meniscus in children and young athletes. METHODS: Arthroscopic meniscus repairs performed on 49 knees in 31 male and 14 female patients <18 years old were reviewed. All repairs were done using an inside-out technique, and 31 patients required concomitant anterior cruciate ligament (ACL) reconstruction. Age at time of injury, time to surgery, and the extent, type, and location of meniscus tear were noted. All patients underwent postoperative rehabilitation and clinical evaluation. The level of activity at follow-up and postoperative outcomes scores was determined. Analysis included t tests, Wilcoxon tests, χ tests, and Fisher exact tests, with a level of significance of P ≥ 0.05. RESULTS: Excellent clinical outcomes were noted in 43 of 45 patients, with mean length of follow-up of 27 months. Between the groups with and without ACL tears, there were no significant differences in mean age at the time of injury or surgery, or in the distribution of open versus closed physes, medial versus lateral repairs, or level-of-activity at follow-up. However, patients with ACL reconstruction had significantly longer return-to-activity times (mean 8.23 mo vs. 5.56 mo) and significantly lower Tegner scores (mean 6.8 vs. 8.0) than patients without simultaneous reconstruction. CONCLUSIONS: The clinical results after arthroscopic meniscus repair in the adolescent were excellent, despite long average time from injury to surgery and a high number of tears in poorly vascularized areas. Meniscal tears in skeletally immature athletes may have greater reparative potential, with and without simultaneous ligament reconstruction. Attempts at repair regardless of time from injury or location of tear should be strongly considered in this age group. LEVEL OF EVIDENCE: Level III retrospective cohort series.