Pedicled medial sural perforator flap for the reconstruction of knee defects

Soft tissue defects exposing the patellar tendon or bone are common in patients who have experienced trauma or implant infection. The purpose of this article is to present our experience of six patients who underwent reconstruction of soft tissue defects of the knee using a pedicled medial sural perforator flap. Between November 2013 and November 2015, six patients who presented with a soft tissue defect overlying the knee were admitted to our hospital. After adequate debridement or wide excision of the tumour, these patients underwent pedicled medial sural perforator flap placement to resurface the complex soft tissue defects and to provide a gliding surface for the exposed patellar tendon. The patients' age, comorbidity, aetiology, defect size and location, flap size, perforator numbers and lengths, outcome and follow‐up period were reviewed. The six medial sural perforator flaps survived completely, and the wounds healed satisfactorily over a mean follow‐up of 21·5 months (range, 6–51 months). Donor sites were closed primarily or covered with a split‐thickness skin graft. The medial sural perforator flap is a reliable flap for coverage of defects overlying the knee. The thin and pliable flap, long pedicle length and less donor site mobility benefit patients. Thus, the medial sural perforator flap may be a valuable alternative for defect reconstructions overlying the knee, which produces satisfactory results both functionally and cosmetically.     

Metal ion concentrations and semen quality in patients undergoing hip arthroplasty: A prospective comparison between metal‐on‐metal and metal‐on‐polyethylene implants

Purpose: The widespread usage of metal‐on‐metal (MoM) articulations in total hip arthroplasty (THA) has been tempered by concerns of increased metal ion production. The purpose of the study is to evaluate the influence of metal ion exposure on semen quality in young male patients undergoing THA. Methods: Male patients who were scheduled for unilateral THA and aged between 20 and 45 years were prospectively enrolled. Patients were sorted into MoM and metal‐on‐polyethylene (MoP) groups with equal case number. Semen and blood metal ion levels were measured and sperm analysis was performed before, 6 months after, and 1 year after surgery. Results: Compared to preoperative baseline, patients (n = 50) in both groups had increased cobalt (Co) and chromium (Cr) concentrations in blood and seminal fluid after surgery. Between‐group comparisons at 6 months and 1 year after surgery showed that patients in the MoM group both had a greater Co concentration in blood and semen and a greater Cr concentration in blood and semen. Patients receiving MoM prosthesis had a reduced percentage of morphologically normal sperm, and decreases from the preoperative level (44.7%) were significant at 6 months (36.8%, p = 0.03) and 1 year (33.8%, p = 0.004). Conclusions: Our data shows a significantly greater concentration of metal ion in blood and semen in patients with MoM prosthesis with a reduced percentage of morphologically normal sperm. Despite small effects on sperm quality, some concerns remain. Further studies are necessary to determine sources of metal ion and to investigate effects on male fertility. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:544–551, 2016.     

Identification of amino acid residues responsible for the release of free drug from an antibody-drug conjugate utilizing lysine-succinimidyl ester chemistry

Unexpected release of free drug was observed during the stability testing of an antibody-drug conjugate (ADC). The ADC was designed to use lysine-succinimidyl ester chemistry to conjugate small molecule cytotoxic drugs to the antibody. To elucidate the mechanism of the release of free drug, a succinimidyl ester analog, 7-hydroxy-4-methyl-3-coumarinylacetic acid N-succinimidyl ester, and a series of peptides were used to probe the potential side reaction of succinimidyl ester with other amino acid residues. Cysteine and tyrosine residues were found to be reactive to succinimidyl ester, and the bonds formed through these reactions were found to be labile. Combining the fluorescent property of the succinimidyl ester analog and mass spectroscopy analysis, specific cysteine and tyrosine residues of the antibody were found to be reactive to succinimidyl ester and the bonds formed through this reaction were susceptible to hydrolysis.