Martinez, Frank A.

Case: A 51-year-old man and 64-year-old woman with bilateral cruciate-retaining total knee arthroplasties (CR-TKAs) who sustained unilateral periprosthetic distal femur fractures above their CR-TKA and experienced knee instability secondary to an iatrogenic posterior-cruciate-ligament (posterior cruciate ligament [PCL]) injury from retrograde intramedullary nailing. Both patients recovered knee stability after undergoing revision surgery. Conclusion: Many CR-TKA designs have sufficient medial-lateral intercondylar distance to place a retrograde nail, femoral components with a relatively posterior transition from the trochlear groove to the intercondylar box will necessitate a nail starting point closer to the PCL origin. This may contribute to iatrogenic postoperative knee instability for patients with CR-TKA designs.

Case: A 76-year-old woman with multiple myeloma and osteoporosis presented with right hip pain and an impending atypical femoral fracture in the setting of chronic bisphosphonate use. After preoperative medical optimization, she was scheduled for prophylactic intramedullary nail fixation. Intraoperatively, the patient experienced episodes of severe bradycardia and asystole associated with intramedullary reaming, which ceased after distal venting of the femur. No additional intraoperative or postoperative complications were encountered, and the patient recovered uneventfully. Conclusion: Femoral canal venting may be an appropriate intervention for similar transient dysrhythmias caused by intramedullary reaming.

Congenital hydrocephalus after peripartum infection usually presents early in life; however, we present a 92-year-old female patient with newly diagnosed hydrocephalus secondary to peripartum infection. Intracranial imaging showed ventriculomegaly, calcifications bilaterally throughout the cerebral hemispheres, and findings suggesting a chronic process. This presentation is most likely to occur in low-resource settings, and given the risks of operation, conservative management was preferred.

A 25-year-old man presented with left-sided hearing loss, blurred vision and papilloedema. Imaging revealed a large, left-sided, contrast-enhancing cerebellopontine mass causing obstructive hydrocephalus, consistent with vestibular schwannoma (VS). Following an incomplete resection via retrosigmoid craniotomy at an outside facility, he was referred to our department, and cerebrospinal fluid diversion followed by repeat resection was recommended. A subtotal resection was achieved, and the patient was subsequently treated with adjuvant stereotactic radiosurgery (SRS). Progressive interval growth was observed on serial post-SRS MRI studies; correspondingly, at 31 months after treatment, the patient was initiated on antiprogrammed-death receptor 1 (PD-1) antibody treatment with pembrolizumab. Growth arrest was noted on subsequent serial imaging studies, which have been maintained for a total of 30 months since initiation of a 18-month anti-PD-1 course of therapy. Additional case accumulation and translational study is required to better characterise this therapeutic strategy; however, PD-1/programmed death-ligand 1 inhibition may offer a promising salvage therapy for refractory VS.