Outcomes in the treatment of periprosthetic joint infection after shoulder arthroplasty: a systematic review.

BACKGROUND: Although many case series have been published on the treatment of shoulder periprosthetic joint infection (PJI), few provide direct comparison of outcomes. This systematic review synthesizes the available English literature on shoulder PJI to quantify treatment effectiveness. METHODS: The PubMed and Embase databases were searched in April 2014. Keywords included "shoulder replacement infection" and "shoulder arthroplasty infection." Of 663 titles, 55 manuscripts underwent full-text review after application of exclusion criteria. Thirty articles were finally included. RESULTS: Propionibacterium acnes was most commonly reported, representing 38.9% of infections, followed by Staphylococcus species. Risk factors for shoulder PJI include previous surgery, increased age, male gender, increased body mass index, and diabetes mellitus. The average white blood cell count in 13 studies was 7472 cells/µL. Ten studies reported a mean erythrocyte sedimentation rate of 27.6 mm/h, whereas 14 studies reported a mean C-reactive protein level of 2.6 mg/dL. P. acnes in intraoperative culture specimens was an independent risk factor for failed treatment for shoulder PJI. When outcomes were pooled, no statistical difference was found in the success rates of 1-stage, 2-stage, or resection arthroplasty revision; each displayed a success rate >90%. However, single-stage revision produced the highest mean Constant score; implant retention resulted in the best range of motion. CONCLUSIONS: Our data suggest that single-stage revision can be as effective as 2-stage or resection treatments; however, the retrospective nature of these data precluded our ability to control for confounding variables. Future studies on shoulder PJI should involve direct comparisons of 1-stage vs. 2-stage treatment while comparing cost, morbidity, and functional outcomes.

Leukocyte esterase in the diagnosis of shoulder periprosthetic joint infection.

BACKGROUND: Shoulder periprosthetic joint infection (PJI) is difficult to diagnose with traditional methods. Leukocyte esterase (LE) has recently proven to be reliable in knee arthroplasty; however, its value in the shoulder has not been explored. We hypothesized that LE would display high sensitivity and specificity in shoulder PJI. METHODS: Two groups were prospectively evaluated: 45 primary and 40 revision shoulder arthroplasties. Synovial fluid and soft tissue cultures were obtained at surgery. Synovial fluid was evaluated with LE test strips. Any aspiration that contained erythrocytes was centrifuged and retested. Shoulder PJI was defined by modified Musculoskeletal Infection Society (MSIS) criteria. RESULTS: Of 5 primaries with positive tissue cultures (11%), only 1 was positive for LE. Of 16 revisions with positive cultures (40%), 4 had positive LE results. Among all patients with bacterial isolates, 6 aspirates were not interpretable (29%), despite centrifugation. LE had sensitivity of 25% and specificity of 75% to predict positive cultures in revisions. Ten revision patients met modified MSIS criteria for PJI. The sensitivity of LE in these patients was 30%, and the specificity was 67% (positive predictive value, 43%; negative predictive value, 83%). If bloody aspirates were considered positive, LE sensitivity in MSIS PJI increased to 60%, but the positive predictive value fell to 37.5%. CONCLUSION: LE is an unreliable diagnostic measure in shoulder PJI. The presence of erythrocytes within aspirates further decreased its accuracy. We conclude that LE should not be used for the routine identification of shoulder PJI.

The impact of patient activity level on wrist disability after distal radius malunion in older adults.

OBJECTIVE: To determine if high-activity older adults are adversely affected by distal radius malunion. DESIGN: Cross-sectional study. SETTING: Hand clinics at a tertiary institution. PARTICIPANTS: Ninety-six patients 60 years or older at the time of fracture were evaluated at least 1 year after distal radius fracture. INTERVENTION: Physical Activity Scale of the Elderly scores stratified participants into high- and low-activity groups. Malunions were defined radiographically by change of ≥20 degrees of lateral tilt, ≥15 degrees radial inclination, ≥4 mm of ulnar variance, or ≥4 mm intra-articular gap or step-off, compared with the uninjured wrist. MAIN OUTCOME MEASURE: Patient-rated disability of the upper extremity was measured by the QuickDASH and visual analog scales (VAS) for pain/function. Strength and motion measurements objectively quantified wrist function. RESULTS: High-activity participants with a distal radius malunion were compared with high-activity participants with well-aligned fractures. There was no significant difference in QuickDASH scores, VAS function, strength, and wrist motion despite statistically, but not clinically, relevant increases in VAS pain scores (difference 0.5, P = 0.04) between the groups. Neither physical Activity Scale of the Elderly score (ß = 0.001, 95% confidence interval: -0.002 to 0.004) nor malunion (ß = 0.133, 95% confidence interval: -0.26 to 0.52) predicted QuickDASH scores in regression modeling after accounting for age, sex, and treatment. Operative management failed to improve outcomes and resulted in decreased grip strength (P = 0.05) and more frequent complications (26% vs. 7%, P = 0.01) when compared with nonoperative management. CONCLUSIONS: Even among highly active older adults, distal radius malunion does not affect functional outcomes. Judicious use of operative management is warranted provided heightened complication rates. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Pectoralis major tendon transfer for irreparable subscapularis tears.

BACKGROUND: Subscapularis insufficiency is a debilitating condition with few treatment options. Historically, pectoralis major tendon transfer has been suggested when the subscapularis tendon or muscle is deemed irreparable; however, the results of this salvage procedure have been mixed. METHODS: A comprehensive review of the peer-reviewed literature addressing pectoralis major tendon transfers was performed. The clinical presentation, relevant anatomy, biomechanical rationale, surgical indications, technical considerations, reported outcomes, and significant complications are reviewed in this report. Where possible, attempts at direct comparison of outcomes among surgical techniques and surgical indications have been made. RESULTS AND CONCLUSIONS: Despite the heterogeneous reporting of clinical results, it is clear that surgical indications affect outcomes. Specifically, isolated subscapularis insufficiency shows the best prognosis with pectoralis major tendon transfer. Patients with anterosuperior instability after large rotator cuff tears or shoulder arthroplasty have the least predictable pain relief and worse functional outcomes. LEVEL OF EVIDENCE: Review article.

Elbow arthroscopy: early complications and associated risk factors.

BACKGROUND: Elbow arthroscopy is increasingly used to treat complex pathology. The purpose of this study was to investigate early complication rates after elbow arthroscopy and identify risk factors for adverse events. METHODS: Consecutive elbow arthroscopies performed during a 13-year period were reviewed, identifying early perioperative complications. Major complications included deep infection, permanent nerve injury, or complications requiring additional anesthesia. Minor complications included superficial wound complications and transient nerve palsies. Complications were compared with a surgical complexity scale based on the procedure performed, the number of arthroscopic portals, and tourniquet time. RESULTS: Of 417 procedures, there were 37 minor (8.9%) and 20 major (4.8%) complications. The rates of superficial and deep infections were 6.7% and 2.2%, respectively. Major complications included 9 deep infections, 6 cases of heterotopic ossification requiring further surgery, and 4 manipulations under anesthesia. There were 7 transient sensory nerve complications, and no motor deficits. No differences in complication rates were seen between low-, moderate-, and high-complexity (10.2%, 16.3% and 14.4%, respectively) cases. Intraoperative steroid injections were strongly associated with postoperative superficial (14.1% vs 2.0%) and deep infection (4.9% vs 0.4%) in elbows receiving vs those not receiving steroid (P < .0001). CONCLUSIONS: Complications of elbow arthroscopy are seen in approximately 14% of cases. Most complications are minor, not affecting clinical outcome. Major complications occur in 5% of cases, often requiring repeat surgery. Intraoperative postsurgical steroid injections are associated with increased risk of perioperative infections. Case complexity does not appear to affect the rate of complications with modern surgical techniques.

Intrasynovial flexor tendon repair: a biomechanical study of variations in suture application in human cadavera.

To improve the functional outcomes of intrasynovial tendon suture, prior experiments evaluated individual technical modifications used in the repair process. Few studies, however, have assessed the combinatorial effects of those suture modifications in an integrated biomechanical manner, including a sample size sufficient to make definitive observations on repair technique. Two hundred fifty-six flexor tendon repairs were performed in human cadavera, and biomechanical properties were determined. The effects of five factors for flexor tendon repair were tested: core suture caliber (4-0 or 3-0), number of sutures crossing the repair site (four- or eight-strand), core suture purchase (0.75 or 1.2 cm), peripheral suture caliber (6-0 or 5-0), and peripheral suture purchase (superficial or 2 mm). Significant factors affecting the properties of the repair were the number of core suture strands and the peripheral suture purchase. The least significant factors were core suture purchase and peripheral suture caliber. The choice of core suture caliber affected the properties of repair marginally. Based on these results, we recommend that surgeons continue to focus on multi-strand repair methods, as the properties of eight-strand repairs were far better than those of four-strand repairs. To resist gap formation and enhance repair strength, a peripheral suture with 2 mm purchase is also recommended. Finally, since core suture caliber affected some biomechanical properties, including the failure mode, a 3-0 suture could be considered, provided that future in vivo studies can confirm that gliding properties are not adversely influenced.

Tissue-engineered arterial grafts: long-term results after implantation in a small animal model.

BACKGROUND: Use of prosthetic vascular grafts in pediatric vascular surgical applications is limited because of risk of infection, poor durability, potential for thromboembolic complications, and lack of growth potential. Construction of an autologous neovessel using tissue engineering technology offers the potential to create an improved vascular conduit for use in pediatric vascular applications. METHODS: Tissue-engineered vascular grafts were assembled from biodegradable tubular scaffolds fabricated from poly-L-lactic acid mesh coated with epsilon-caprolactone and L-lactide copolymer. Thirteen scaffolds were seeded with human aortic endothelial and smooth muscle cells and implanted as infrarenal aortic interposition grafts in SCID/bg mice. Grafts were analyzed at time-points ranging from 4 days to 1 year after implantation. RESULTS: All grafts remained patent without evidence of thromboembolic complications, graft stenosis, or graft rupture as documented by serial ultrasound and computed tomographic angiogram, and confirmed histologically. All grafts demonstrated extensive remodeling leading to the development of well-circumscribed neovessels with an endothelial inner lining, neomedia containing smooth muscle cells and elastin, and a collagen-rich extracellular matrix. CONCLUSIONS: The development of second-generation tissue-engineered vascular grafts shows marked improvement over previous grafts and confirms feasibility of using tissue engineering technology to create an improved arterial conduit for use in pediatric vascular surgical applications.

Tissue-engineered vascular grafts demonstrate evidence of growth and development when implanted in a juvenile animal model.

INTRODUCTION: The development of a living, autologous vascular graft with the ability to grow holds great promise for advancing the field of pediatric cardiothoracic surgery. OBJECTIVE: To evaluate the growth potential of a tissue-engineered vascular graft (TEVG) in a juvenile animal model. METHODS: Polyglycolic acid nonwoven mesh tubes (3-cm length, 1.3-cm id; Concordia Fibers) coated with a 10% copolymer solution of 50:50 L-lactide and epsilon-caprolactone were statically seeded with 1 x 10 cells/cm autologous bone marrow derived mononuclear cells. Eight TEVGs (7 seeded, 1 unseeded control) were implanted as inferior vena cava (IVC) interposition grafts in juvenile lambs. Subjects underwent bimonthly magnetic resonance angiography (Siemens 1.5 T) with vascular image analysis (www.BioimageSuite.org). One of 7-seeded grafts was explanted after 1 month and all others were explanted 6 months after implantation. Neotissue was characterized using qualitative histologic and immunohistochemical staining and quantitative biochemical analysis. RESULTS: All grafts explanted at 6 months were patent and increased in volume as measured by difference in pixel summation in magnetic resonance angiography at 1 month and 6 months. The volume of seeded TEVGs at explant averaged 126.9% +/- 9.9% of their volume at 1 month. Magnetic resonance imaging demonstrated no evidence of aneurysmal dilation. TEVG resembled the native IVC histologically and had comparable collagen (157.9 +/- 26.4 microg/mg), elastin (186.9 +/- 16.7 microg/mg), and glycosaminoglycan (9.7 +/- 0.8 microg/mg) contents. Immunohistochemical staining and Western blot analysis showed that Ephrin-B4, a determinant of normal venous development, was acquired in the seeded grafts 6 months after implantation. CONCLUSIONS: TEVGs demonstrate evidence of growth and venous development when implanted in the IVC of a juvenile lamb model.

Functional small-diameter human tissue-engineered arterial grafts in an immunodeficient mouse model: preliminary findings.

HYPOTHESIS: The immunodeficient (severe combined immunodeficiency beige [SCID/bg]) mouse model provides a useful model for investigating vascular neotissue formation in human tissue-engineered arterial conduits (TEAC). DESIGN: Human aortic smooth muscle cells and endothelial cells were statically seeded on porous biodegradable polymeric scaffolds for vascular tissue engineering. These 2-cell tissue-engineered vascular conduits were implanted into immunodeficient female mice as aortic interposition grafts. Grafts were evaluated over a 30-week course to investigate their patency and structure. SETTING: In vivo animal study. PATIENTS: Thirteen female C.B-17 SCID/bg mice. INTERVENTION: The TEACs implanted as infrarenal abdominal aortic interposition grafts. MAIN OUTCOME MEASURES: Selective microcomputed tomography with intra-arterial contrast revealed graft patency and structure. Histological and immunohistochemical evaluations revealed cellularity and extracellular matrix composition. Species-specific immunohistochemical evaluation determined the source of cells within TEACs. RESULTS: All TEACs were patent without evidence of thrombosis or rupture over the 30-week course. Histological and immunohistochemical evaluation revealed a von Willebrand factor-positive luminal monolayer surrounded by concentric collagen-rich layers of alpha-smooth muscle actin-positive cells. CONCLUSIONS: The SCID/bg mouse is a useful model for investigating vascular neotissue formation in human TEACs. We see evidence that these grafts remain patent while developing into vascular neotissue histologically similar to native aorta. This chimeric animal model also enables determination of seeded cell retention, providing insight into cellular mechanisms underlying neotissue formation.

Small-diameter biodegradable scaffolds for functional vascular tissue engineering in the mouse model.

The development of neotissue in tissue engineered vascular grafts remains poorly understood. Advances in mouse genetic models have been highly informative in the study of vascular biology, but have been inaccessible to vascular tissue engineers due to technical limitations on the use of mouse recipients. To this end, we have developed a method for constructing sub-1mm internal diameter (ID) biodegradable scaffolds utilizing a dual cylinder chamber molding system and a hybrid polyester sealant scaled for use in a mouse model. Scaffolds constructed from either polyglycolic acid or poly-l-lactic acid nonwoven felts demonstrated sufficient porosity, biomechanical profile, and biocompatibility to function as vascular grafts. The scaffolds implanted as either inferior vena cava or aortic interposition grafts in SCID/bg mice demonstrated excellent patency without evidence of thromboembolic complications or aneurysm formation. A foreign body immune response was observed with marked macrophage infiltration and giant cell formation by post-operative week 3. Organized vascular neotissue, consisting of endothelialization, medial generation, and collagen deposition, was evident within the internal lumen of the scaffolds by post-operative week 6. These results present the ability to create sub-1mm ID biodegradable tubular scaffolds that are functional as vascular grafts, and provide an experimental approach for the study of vascular tissue engineering using mouse models.

Centrifugal seeding increases seeding efficiency and cellular distribution of bone marrow stromal cells in porous biodegradable scaffolds.

Bone marrow stromal cells (MSCs) are a promising cell source for a variety of tissue engineering applications, given their ready availability and ability to differentiate into multiple cell lineages. MSCs have been successfully used to create neotissue for cardiovascular, urological, and orthopedic reconstructive surgical procedures in preclinical studies. The ability to optimize seeding techniques of MSCs onto tissue engineering scaffolds and the ability to control neotissue formation in vitro will be important for the rational design of future tissue engineering applications using MSCs. In this study we investigated the effect of centrifugal force on seeding MSCs into a biodegradable polyester scaffold. MSCs were isolated and seeded onto porous scaffold sections composed of nonwoven polyglycolic acid mesh coated with poly(L-lactide-co-epsilon-caprolactone). Compared to standard static seeding techniques, centrifugal seeding increased the seeding efficiency by 38% (p < 0.007) and significantly improved cellular distribution throughout the scaffold. Overall, centrifugal seeding of MSCs enhances seeding efficiency and improves cellular penetration into scaffolds, making it a potentially useful technique for manipulating neotissue formation by MSCs for tissue engineering applications.