A high rate of tibial plateau fractures after early experience with patient-specific instrumentation for unicompartmental knee arthroplasties.

PURPOSE: Patient-specific instrumentation (PSI) for unicompartmental knee arthroplasty (UKA) has been available for a few years. However, limited literature is available on this subject. Hence, the aim of this cohort study is to evaluate the 2 years' results of our first experiences with the use of PSI in UKA. It is hypothesised that there is no advantage in rate of adverse events and in radiological and functional outcomes in comparison to literature on the conventional method. METHODS: This cohort included 129 knees of 122 patients, operated by one surgeon. Outcome measures were the rate of adverse events (AEs); implant position as determined on radiographs; the accuracy of the default and approved planning of the implant sizes and the patient-reported outcome measures (PROMs) preoperatively, and at 3, 12 and 24 months, postoperatively. RESULTS: A total of 6 (4.9%) AEs were observed in this study, with 4 (3.3%) tibial fractures being the main complication. The mean postoperative biomechanical axis was 176.4° and in the majority of cases, the radiographic criteria, as determined by the manufacturer, were met. The tibial component showed 20 (16.4%) outliers in the sagittal and 3 (2.5%) outliers in the frontal plane. There were no outliers of the femoral component. For the femoral and tibial components, respectively, in 125 (96.9%) and 79 (61.7%) cases, there was an agreement between approved planning and implanted component size. All PROMs improved significantly after surgery. CONCLUSION: Tibial fracture was the most common AE, probably related to the transition from cemented to uncemented UKA. Perioperative modifications to the surgical technique were made in order to prevent this AE. Improvements should be made to the operation technique of the uncemented tibial plateau to obtain an adequate placement and at the same time reduce the risk for tibial fracture. The PSI technique was a reliable tool for the placement of the femoral component. Functional outcome was in line with literature on the conventional method. It is strongly recommended that the surgeon approves every preoperative plan, in order to optimise the accuracy during the PSI surgery. LEVEL OF EVIDENCE: III.

Endometriosis of the groin: the additional value of magnetic resonance imaging (MRI).

We report a rare case of endometriosis of the groin in a young woman. This case shows how difficult the diagnosis of unusual manifestations of endometriosis can be. The diagnosis was suspected by a careful history and physical examination. Diagnosis was supported by timely performed Magnetic Resonance Imaging, which illustrates its additional value. It can be argued that MRI could be the first choice of imaging technique for the assessment of young women with nonspecific or unexplained complaints of the groin. Even more important is the familiarity of physicians other than gynaecologists with rare manifestations of this common disease.

Transient osteoporosis of the hip and spontaneous osteonecrosis of the knee: a common aetiology?

INTRODUCTION: The aetiologies of transient osteoporosis of the hip (TOH) and spontaneous osteonecrosis of the knee (SONK) are still unknown. Both entities present with pain and extensive bone marrow oedema is seen on magnetic resonance imaging. METHODS AND MATERIALS: We describe a patient who presented with TOH and later also developed SONK. Initial magnetic resonance imaging findings of both the hip and the knee showed extensive bone marrow oedema and a subchondral fracture line suggesting that subchondral fractures might be of importance to the aetiology of both conditions. CONCLUSION: To our knowledge, this is the first case report that describes the occurrence of TOH and SONK in the same patient and introduces the possibility of a common aetiology.