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The authors report a case of nontraumatic, spontaneous dislocation of a polyethylene insert detected 1 year after total knee arthroplasty. The patient demonstrated initial improvement and returned to work 4 months postoperatively. At 6 months postoperatively, the patient developed pain and a clunking sensation with motion; however, he denied any traumatic precipitating events. An arthroscopic procedure revealed arthrofibrotic formations but no signs of locking mechanism failure. At 12 months postoperatively, the patient developed sudden instability, and radiographs demonstrated an anteriorly dislodged insert. Revision surgery was performed, and the insert was removed. The insert showed some signs of fatigue due to the locking mechanism. We postulated that repetitive flexion produced an anterior superior force leading to failure of the locking mechanism.

Unilateral femoral neck stress fractures are well documented in active patients; however, the risk of a subsequent contralateral stress fracture remains unknown in patients who continue to be active. This article describes a 24-year-old male fire academy student who sustained a left femoral neck stress fracture, followed approximately 11 months later by a right femoral neck stress fracture, both of which went on to completely displace. A review of the index radiographs of each hip from outside institutions revealed femoral neck stress fractures that went undiagnosed until they displaced. The patient was referred to our institution and underwent closed reduction and internal fixation using cannulated screws in both cases. A full endocrine evaluation was performed in the following weeks and proved unremarkable. Although it is difficult to extrapolate the results from 1 patient beyond the case studied, there is cause for concern in patients who remain active following femoral neck stress fractures. Our case highlights the significance of obtaining a complete and thorough medical history on physical examination and appropriately counseling patients regarding activity level. Until further research explores this possible relationship, physicians evaluating patients with a history of a stress fracture are encouraged to be vigilant of subsequent contralateral fractures and educate patients of this potentially avoidable injury.

This article presents 2 cases of foot drop after joint replacement surgery that presented after sequential compression device application. In both cases, intact peroneal nerve function was documented by the surgeon in the recovery room prior to sequential compression device application. We believe that excessive pressure over the superficial aspect of the peroneal nerve in conjunction with decreased pain stimulus from analgesia may have contributed to these complications. We maintain sequential compression devices are the current mechanical thromboprophylaxis of choice; however, 4 recommendations are made to minimize the chances of this potential complication. First, precise attention should be given to patients who are short statured, as these patients can be more susceptible to having a sequential compression device improperly placed over the peroneal nerve at the fibular neck. Second, we recommend different size options become more widely available to accommodate varying patient sizes such that placement of the device is ensured to be distal to the fibular neck. Third, when using sequential compression device brands that have hook and look fastener straps, the straps should not be tight on application and frequent skin checks should be made to look for signs of over-compression. Lastly, we recommend considering delaying postoperative application of the sequential compression device until resolution of sensation following spinal or epidural anesthetic.

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