Surgical reattachment of torn rotator cuff tendons can lead to satisfactory clinical outcome but failures remain common. Ortho-R product is a freeze-dried formulation of chitosan (CS) that is solubilized in platelet-rich plasma (PRP) to form injectable implants. The purpose of the current pilot study was to determine Ortho-R implant acute residency, test safety of different implant doses, and assess efficacy over standard of care in a sheep model. The infraspinatus tendon (ISP) was detached and immediately repaired in 22 skeletally mature ewes. Repair was done with four suture anchors in a suture bridge configuration (n = 6 controls). Freeze-dried formulations containing 1% w/v chitosan (number average molar mass 35 kDa and degree of deacetylation 83%) with 1% w/v trehalose (as lyoprotectant) and 42.2 mM calcium chloride (as clot activator) were solubilized with autologous leukocyte-rich PRP and injected at the tendon-bone interface and on top of the repaired site (n = 6 with a 1 mL dose and n = 6 with a 2 mL dose). Acute implant residency was assessed histologically at 1 day (n = 2 with a 1 mL dose and n = 2 with a 2 mL dose). Outcome measures included MRI assessment at baseline, 6 weeks and 12 weeks, histopathology at 12 weeks and clinical pathology. MRI images and histological slides were scored by 2 blinded readers (veterinarian and human radiologist, and veterinarian pathologist) and averaged. The Generalized Linear Model task (SAS Enterprise Guide 7.1 and SAS 9.4) was used to compare the different groups with post-hoc analysis to test for pairwise differences. Ortho-R implants were detected near the enthesis, near the top of the anchors holes and at the surface of ISP tendon and muscle at 1 day. Numerous polymorphonuclear cells were recruited to the implant in the case of ISP tendon and muscle. On MRI, all repair sites were hyperintense compared to normal tendon at 6 weeks and only 1 out 18 repair sites was isointense at 12 weeks. The tendon repair site gap seen on MRI, which is the length of the hyperintense region between the greater tuberosity and tendon with normal signal intensity, was decreased by treatment with the 2 mL dose when compared to control at 12 weeks (p = 0.01). Histologically, none of the repair sites were structurally normal. A trend of improved structural organization of the tendon (p = 0.06) and improved structural appearance of the enthesis (p = 0.1) with 2 mL dose treatment compared to control was seen at 12 weeks. There was no treatment-specific effect on all standard safety outcome measures, which suggests high safety. Ortho-R implants (2 mL dose) modulated the rotator cuff healing processes in this large animal model. The promising MRI and histological findings may translate into improved mechanical performance, which will be assessed in a future study with a larger number of animals. This study provides preliminary evidence on the safety and efficacy of Ortho-R implants in a large animal model that could potentially be translated to a clinical setting.
The current recommendation by the AAOS in the 2010 clinical practice guidelines for the use of MRI to diagnose a periprosthetic joint infection (PJI) is “inconclusive” given the lack of evidence to support its use. The purpose of this study was to determine the utility of MRI with metal reduction artifact sequencing in diagnosing a periprosthetic joint infection (PJI) after total hip arthroplasty (THA). 176 patients who underwent MRI with multi-acquisition variable resonance image combination (MAVRIC) to reduce metal artifact for a painful THA between the years of 2009–2013 were retrospectively evaluated. All MRIs were read by one of four radiologists with extensive experience in interpreting MRIs after THA. All MRIs were performed using a 1.5 Tesla magnet. Of the 176 patients examined, 16 patients were found to have a deep periprosthetic joint infection using Musculoskeletal Infection Society (MSIS) criteria after the MRI was performed. MRI reads were classified as either positive (read as “evidence of active infection” or “suspicious for infection”) or negative (read as no evidence of infection). Only one patient who had a positive MRI read was excluded because of loss to followup after the MRI was performed.Introduction
Methods
The current recommendation by the AAOS in the 2010 clinical practice guidelines for the use of MRI to diagnose a periprosthetic joint infection (PJI) is “inconclusive” given the lack of evidence to support its use. The purpose of this study was to determine the utility of MRI with metal reduction artifact sequencing in diagnosing a periprosthetic joint infection (PJI) after total hip arthroplasty (THA). 176 patients who underwent MRI with multi-acquisition variable resonance image combination (MAVRIC) to reduce metal artifact for a painful THA between the years of 2009–2013 were retrospectively evaluated. All MRIs were read by one of four radiologists with extensive experience in interpreting MRIs after THA. All MRIs were performed using a 1.5 Tesla magnet. Of the 176 patients examined, 16 patients were found to have a deep periprosthetic joint infection using Musculoskeletal Infection Society (MSIS) criteria after the MRI was performed. MRI reads were classified as either positive (read as “evidence of active infection” or “suspicious for infection”) or negative (read as no evidence of infection). Only one patient who had a positive MRI read was excluded because of loss to followup after the MRI was performed.Introduction
Methods
The earliest evidence of particle-induced response is found in the synovium, leading to osteolytic defect. The degree of synovitis can be quantified by magnetic resonance imaging (MRI). This is the first long-term, prospective, matched-pair study using MRI to analyze wear-induced synovitis and osteolysis between rotating-platform posterior-stabilized (RP-PS), fixed-bearing metal-back (FB-MB), and all-polyethylene tibial (APT) designs in active patients with identical femoral components and polyethylene. From September 1999 to October 2001, a matched-pair analysis of 24 TKAs (18 patients, 3 groups: 8 RP-PS, 8 FB-MB, and 8 APT) was performed. TKAs were matched for age, sex, body mass index (BMI), and University of California Los Angeles (UCLA) activity scores. All patients underwent MRI using MAVRIC (multi-acquisition variable-resonance image combination) knee protocol designed to reduce metal susceptibility artifact. Images were evaluated for volumetric measure of synovitis and/or osteolysis and presence of fibrous membrane formation at the cement-bone interface.Introduction:
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