More and more patients with end-stage knee OA are treated with total knee replacements (TKR). A modern TKR (Persona PS system, Zimmer Inc.) was designed with the hope to improve fit by providing additional sizing options on the femur and tibia. To date, there is very little information regarding the knee strength and knee mechanics during gait after the TKR. Furthermore, as a great percentage of knee OA patients have OA limited in one knee compartment and in the patellofemoral joint, a bi-compartmental knee replacement (BKR) (iDUO system, ConforMIS Inc.) was designed to treat OA at these affected areas. The BKR re-creates the individual's knee shape while correcting for any deformity. In addition, the BKR procedure results in less bone loss and retains the cruciate ligaments. To date, the influence of the BKR on knee strength and knee mechanics remains unknown. The purpose of the study was to evaluate knee strength and mechanics during level walking after the TKR and BKR surgeries. Twelve healthy control participants (age=57±6 yr.; mass=82±11 kg; height=175±11 cm), eight patients (age=63±10 yr.; mass=87±20 kg; height=166±8 cm) with ten BKR systems (post-op time = 17±9 mo.), and nine patients (age=65±9 yr.; mass=90±35 kg; Height=169±12 cm) with twelve TKR systems (post-op time = 14±5 mo.) participated in the study. In a laboratory setting, maximal isometric knee strength was evaluated. Motion capture and 3D kinematic and kinetic analyses were conducted for level walking. One way ANOVA was used to determine differences among the BKR, TKR, and the healthy control knees.Background
Methods
Early detection of Developmental Dysplasia of the Hip (DDH), and treatment, may prevent the need for surgical correction following late presentation. Neonatal examination, and ultrasound screening of at risk groups, does not detect all cases. Most neonates treated in the Intensive Care Unit (NICU) have abdominal radiographs performed during their stay. These include the hips but DDH is not routinely looked for. 50 neonatal abdominal films (five from patients who subsequently were found to have DDH, 45 from patients without this condition) were randomly shown to three paediatric orthopaedic surgeons and three paediatric radiologists on two separate occasions. Each was asked whether they would refer the patient for further investigation. An overall sensitivity of 25.5% (Range 0–60%) and specificity of 93.2% (Range 87–97%) was found with a positive predictive value (PPV) of 14.0% (Range 0–37%) and negative predictive value (NPV)of 96.3% (Range 95–98%). Although the low sensitivity and PPV make interpretation of these films a poor way to diagnose DDH, the high specificity and NPV suggest that they may be used as a prompt to further investigation. Therefore, we propose that DDH should be looked for on these films and, where there is radiological suspicion, ultrasound examination should be advised.
