Matthew J. Grosso

α-Defensin as a predictor of periprosthetic shoulder infection

BACKGROUND Diagnosis of periprosthetic joint infection (PJI) in revision shoulder arthroplasty can be challenging because of the indolent nature of the common offending organisms. The purpose of this study was to evaluate the diagnostic utility of synovial fluid α-defensin levels in identifying PJI of the shoulder. METHODS Thirty patients evaluated for painful shoulder arthroplasty were prospectively enrolled and underwent revision surgery (n = 33 cases). Cases were categorized into infection (n = 11) and no-infection (n = 22) groups on the basis of preoperative and intraoperative findings. Synovial fluid was obtained from preoperative aspirations or intraoperative aspiration before arthrotomy. α-Defensin was tested by the Synovasure (CD Diagnostics, Wynnewood, PA, USA) test for joint infection. Synovial fluid was also obtained intraoperatively from a control group undergoing arthroscopic rotator cuff repair (n = 16) for baseline data on normal α-defensin levels in the shoulder. A receiver operating characteristic curve was used to determine the diagnostic utility of synovial fluid α-defensin. RESULTS Synovial α-defensin had an area under the curve, sensitivity, specificity, and positive and negative likelihood ratios of 0.78, 63%, 95%, 12.1, and 0.38, respectively. There was a significant difference in α-defensin levels between the infection (median, 3.2 S/CO [signal to cutoff ratio]) and no-infection groups (median, 0.21 S/CO; P = .006). Synovial α-defensin was elevated in the presence of a culture positive for Propionibacterium acnes (median, 1.33 S/CO; P = .03) and showed moderate correlation with the number of positive cultures. CONCLUSION Synovial fluid α-defensin was more effective than current diagnostic testing in predicting positive cultures and may be an effective adjunct in the workup of shoulder PJI.

Sensitivity of Frozen Section Histology for Identifying Propionibacterium acnes Infections in Revision Shoulder Arthroplasty

BACKGROUND Propionibacterium acnes is a clinically relevant pathogen with total shoulder arthroplasty. The purpose of this study was to determine the sensitivity of frozen section histology in identifying patients with Propionibacterium acnes infection during revision total shoulder arthroplasty and investigate various diagnostic thresholds of acute inflammation that may improve frozen section performance. METHODS We reviewed the results of forty-five patients who underwent revision total shoulder arthroplasty. Patients were divided into the non-infection group (n = 15), the Propionibacterium acnes infection group (n = 18), and the other infection group (n = 12). Routine preoperative testing was performed and intraoperative tissue culture and frozen section histology were collected for each patient. The histologic diagnosis was determined by one pathologist for each of the four different thresholds. The absolute maximum polymorphonuclear leukocyte concentration was used to construct a receiver operating characteristics curve to determine a new potential optimal threshold. RESULTS Using the current thresholds for grading frozen section histology, the sensitivity was lower for the Propionibacterium acnes infection group (50%) compared with the other infection group (67%). The specificity of frozen section was 100%. Using a receiver operating characteristics curve, an optimized threshold was found at a total of ten polymorphonuclear leukocytes in five high-power fields (400×). Using this threshold, the sensitivity of frozen section for Propionibacterium acnes was increased to 72%, and the specificity remained at 100%. CONCLUSIONS Using current histopathology grading systems, frozen sections were specific but showed low sensitivity with respect to the Propionibacterium acnes infection. A new threshold value of a total of ten or more polymorphonuclear leukocytes in five high-power fields may increase the sensitivity of frozen section, with minimal impact on specificity.

Complications and Outcomes for Surgical Approaches to Cervical Kyphosis.

Study Design: Retrospective cohort study. Objective: The primary objective of this study is to report the safety and efficacy of the different surgical approaches to cervical deformity correction surgery. Summary of Background Data: Cervical subaxial deformity surgery has been shown to be an effective means to alleviate pain and improve neurological function in symptomatic patients. The reported outcomes and complications for the different surgical approaches (ventral, dorsal, and combined) are limited to small retrospective studies. The appropriate surgical approach is at times unclear, which is likely attributed to the overlap in indications for the ventral and combined approach. Materials and Methods: A retrospective review of 76 patients who underwent cervical deformity surgery for cervical kyphosis at 1 institution was performed. The authors reviewed the complications, radiographic outcomes, and long-term functional outcomes for all patients. Results: The majority of patients in all groups reported excellent (15%) or good (50%) outcomes, with a mean improvement in modified Japanese orthopedic association score of 1.3. There were 26 perioperative complications (34%) for 19 patients (25%). We found the ventral-alone and combined approaches to achieve similar degrees of correction (23.1 and 23.2 degrees, respectively). The combined approach had the highest complication rate of the 3 approaches (combined: 40%, ventral: 30%, dorsal: 27%). The dorsal, ventral, and combined approaches had a mean neurological improvement in modified Japanese orthopedic association scores of 1.95, 3.00, and 1.26, respectively, and mean pain improvement of 0.8, 2.0, and 1.4. Conclusions: Given the moderate improvements in long-term outcomes, and the risks for perioperative complications, we recommend a careful selection process for patients eligible for cervical deformity surgery. We found that the ventral approach has reduced complications, similar degree of correction capability, and potentially higher improved neurological outcomes compared to the combined approach.

Diagnosis of Periprosthetic Infection After Shoulder Arthroplasty

One of the most serious complications following shoulder arthroplasty is periprosthetic infection. Infection is associated with poor outcomes, increased cost, and technically difficult revision surgery. The prevalence of infection following primary shoulder arthroplasty has been reported to be between 0.7% and 4%, and even higher following revision surgery1-6. Two recent, large retrospective reviews noted infection rates of 0.7% (nineteen of 2540 cases)2 and 1.2% (thirty-two of 2588 cases)6. Bohsali and colleagues reported that deep periprosthetic infections accounted for 4.6% of all complications of total shoulder arthroplasty2. At the time of long-term follow-up, Singh et al. observed five, ten, and twenty-year periprosthetic infection-free rates of 99.3%, 98.5%, …

Effects of an immunomodulatory therapy and chondroitinase after spinal cord hemisection injury.

BACKGROUND Individually, immunomodulatory therapy and chondroitinases have demonstrated neuroprotective and potential neuroregenerative effects following spinal cord injury. OBJECTIVE To investigate the therapeutic potential of combined immunomodulatory and chondroitin sulfate-glycosaminoglycan degradation therapy in spinal cord injury. METHODS A combined immunomodulatory treatment using (1) liposome-encapsulated clodronate (selectively depletes peripheral macrophages), and (2) rolipram (a selective type 4 phosphodiesterase inhibitor), along with the chondroitin sulfate proteoglycan-glycosaminoglycan-degrading enzyme, chondroitinase ABC (ChABC), was assessed for its potential to promote axonal regrowth and improve locomotor recovery following midthoracic spinal cord hemisection injury in adult rats. RESULTS We demonstrate that combined treatment with liposomal clodronate, rolipram, and ChABC attenuates macrophage accumulation at the site of injury, reduces axonal die-back of injured dorsal column axons, and produces the greatest improvement in locomotor recovery at 6 weeks postinjury compared with controls and noncombined therapy. Anterograde and retrograde tracing revealed that delivery of clodronate, rolipram, and ChABC did not promote substantial axonal regeneration through the site of injury, although the treatment did limit the extent of axonal die-back. Histological assessments revealed that combined treatment with clodronate/rolipram and/or ChABC resulted in a significant reduction in lesion size and cystic cavitation in comparison with injured controls. Combined clodronate, rolipram, and ChABC treatment reduced the accumulation of macrophages within the injured spinal cord 7 weeks after injury. CONCLUSION The present data suggest that delivery of an immunomodulatory therapy consisting of clodronate and rolipram, in combination with ChABC, reduces axonal injury and enhances neuroprotection, plasticity, and hindlimb functional recovery after hemisection spinal cord injury in adult rats.

Reverse Total Shoulder Arthroplasty in the Setting of Infection

Introduction: The most common reported complications with RSA have been instability and infection, with higher rates of infection reported in RSA than anatomic shoulder replacement. This chapter focuses on the application of RSA in the setting of infection, including a review of the literature and outcomes, preferred method of treatment, and key points and pearls. Conclusions: Increased rates of infection in RSA are likely due to a larger subacromial–glenohumeral dead space, limited viable soft tissue coverage due to a lack of rotator cuff integrity, or surgeon experience. Because of the indolent nature of the common shoulder pathogen, Propionibacterium acnes, infection is difficult to identify and surgeons should maintain a high degree of suspicion, even when initial testing does not suggest infection because of the poor sensitivity of common preoperative and intraoperative tests. For the majority of chronic infections, two-stage exchange is currently the most common choice for management. Revision to RSA via a one- or two-stage exchange has shown satisfactory outcomes in regard to reinfection rates. Reimplantation requires appropriate development of all soft tissue planes and adequate soft tissue releases to optimize shoulder range-of-motion and joint stability and depending on bone loss could require bone grafting.