Rotational alignment errors can occur in unicompartmental knee arthroplasty if anatomical landmarks are misused: A preoperative CT scan analysis.

BACKGROUND: Accurate implant positioning, including rotation, is essential for successful unicompartmental knee arthroplasty (UKA). This study defined the rotational error that would result in medial UKA when using the medial edge of the tibial tubercle (TT) rather than the medial tibial spine for determining tibial component rotation, and in lateral UKA when aligning the anterior edge of the sagittal tibial cut with the lateral edge of the patellar tendon. METHODS: Preoperative computed tomography (CT) scans were reviewed in 88 knees undergoing medial (n = 71) and lateral (n = 17) UKAs. In medial UKA, the angle between a line along the long axis of the medial tibial spine and a line drawn to the medial edge of the TT was measured. In lateral UKA, the angular relationship between the longitudinal axis of the lateral tibial spine and the lateral edge of the patellar tendon was measured. RESULTS: In medial UKA, an average angular error of 9.6° of external rotation could result if the medial edge of the TT is used to set tibial implant rotation. In lateral UKA, the error of the sagittal tibial cut was an average of 7.1° of excessive external rotation if it is referenced on the lateral edge of the patellar tendon. CONCLUSIONS: The preoperative CT scan analysis showed that using the medial edge of the TT and lateral edge of the patellar tendon to set tibial implant rotation may result in excessive external rotation in medial and lateral UKAs, which could result in kinematic mismatch, suboptimal contact areas and rotational malalignment.

Low rate of iatrogenic complications during unicompartmental knee arthroplasty with two semiautonomous robotic systems.

BACKGROUND: Intraoperative complications due to utilization of robotic assistance during unicompartmental knee arthroplasty have not been reported. While inadvertent soft tissue injury has been reported during total knee and hip arthroplasty with autonomous style robotic systems, the incidence of these problems with semiautonomous (i.e. surgeon-driven) systems is unknown. METHODS: We report on a series of 1064 consecutive unicompartmental knee arthroplasties performed by one surgeon with either one of two commercially available semiautonomous robotic systems. RESULTS: There were no soft tissue, bone injuries or other complications related to the use of the robotic bone preparation method. Six complications related to the use of standard computer navigation pins occurred (0.6%) - one pseudoaneurysm of a branch of the tibialis anterior artery, one tibial metaphyseal stress fracture, and four areas of pin site irritation/superficial infection that resolved with a short course of oral antibiotics. CONCLUSION: Current semiautonomous robotic methods are safe, with few complications using meticulous surgical techniques.

The effect of malnutrition on patients undergoing elective joint arthroplasty.

Malnutrition has been linked to serious complications in patients undergoing elective total joint arthroplasty (TJA). This study prospectively evaluated 2,161 patients undergoing elective TJA for malnutrition as defined by either an abnormal serum albumin or transferrin. The overall incidence of malnutrition was 8.5% (184 of 2,161) and the rate of overall complications in the malnourished group was 12% as compared to 2.9% in patients with normal parameters (P<0.0001). Malnutrition predicted serious complications involving hematoma formation, infection, renal and cardiac complications. Obesity, defined by a body mass index (BMI) of 30kg/m(2) was present in 42.9% of malnourished patients with a significantly higher complication rate in this cohort. Malnutrition remains prevalent in patients >55years-old undergoing TJA and is associated with a significant increase in post-operative complications.

The Field Expedient Extremity Tower (FEET).

The field expedient extremity tower (FEET) is a versatile multipurpose radiolucent lower extremity positioner, which can be constructed from readily available external fixator parts and employed as an intraoperative aid for a variety of lower extremity cases. Examples include intramedullary nailing of the tibia, retrograde nailing of the femur, open or percutaneous plating of the distal femur and proximal tibia as well as skin grafting and wound debridements involving the posterior thigh, leg, and foot. In addition, it allows surgeons in austere environments to perform a wide variety of cases employing modern orthopedic techniques with this dual purpose liquid asset which can readily be broken down and reused as an external fixator if needed.

Bony flexion-distraction injury of the lower lumbar spine treated with instrumentation without fusion and early implant removal: a method of treatment to preserve lumbar motion: two-year follow-up of a teenage patient.

Most single level bony flexion-distraction injuries can be treated in a brace. Internal fixation is required, however, when a patient fails brace treatment. Instrumentation is routinely left in place for a year or more and in an unfused spine can lead to early degenerative changes of the facets and disks. Implant removal once healing has occurred can preserve motion segments in the lumbar spine and offer an advantage in a young patient over instrumentation and fusion. A case report is presented of a 17-year-old female treated successfully with internal fixation without fusion of a bony flexion-distraction injury of the lower lumbar spine with early implant removal and 2-year follow-up.