Young patients have been reported to have a higher risk of revision following total hip arthroplasty (THA) than older cohorts, possibly to due higher activity and a higher incidence of deformity and prior surgery. Ceramic-on-ceramic bearing surfaces have been proposed for use in young and active individuals due to their low wear, low risk of adverse biologic reaction, and long-term survivorship. We assessed the clinical results and long-term survivorship of uncemented ceramic-on-ceramic THA in a young patient population. 341 total hip arthroplasties in 218 patients under 50 years of age at the time of surgery were performed were performed using alumina ceramic-on-ceramic bearings from August 1999 to April 2009 as part of a prospective nonrandomized study. All patients received uncemented acetabular components with flush-mounted acetabular liners using an 18 degree taper and uncemented femoral components. The average patient age at the time of surgery was 41.7 years (range 17.8–49.9 years). The minimum follow-up time was 2 years, (mean 9.1, range 2–13.9). We evaluated implant-related complications and performed Kaplan-Meier analyses to determine survivorship of the femoral and acetabular components with revision for any reason as the endpoint.Introduction:
Methods:
Conventional methods of aligning the acetabular component during hip arthroplasty and hip resurfacing often rely upon anatomic information available to the surgeon. Such anatomical information includes the transverse acetabular ligament and the locations of the pubis, ischium and ilium. The current study assesses the variation in orientation of the plane defined by the pubis, ischium and ilium on a patient-specific basis as measured by CT. To assess the reliability of anatomical landmarks in surgery, we assessed 54 hips in 51 patients (32 male, 22 female) who presented for CT-based surgical navigation of total hip arthroplasty. From a 3D model of each patient, standardised points for the anterior pelvic plane and landmarks on the ilium, ischium, and pubis were entered. The plane defined by the anatomical landmarks was calculated in degrees of operative anteversion and operative inclination according to the definitions of Murray.Introduction
Methods
The optimal acetabular component orientation in general or on a patient-specific basis is currently unknown. In order to answer this question, the current study uses CT to assess acetabular orientation in a group of unstable hips as compared to a control group of stable hips. Our institutional database of CT studies performed in the region of the hip beginning in February of 1998 (41,975 CT studies) was compared against our institutional database of revision total hip arthroplasties beginning in August of 2003 (2262 Revision THA) to identify CT studies of any hip treated for recurrent instability by revision of the acetabular component. Twenty hips in 20 patients with suitable CT studies were identified for the study group. Our control group consisted of 101 hips in patients who had CT studies either for computer-assisted surgery on the contralateral side or for assessment of osteolysis. Using the CT data, the AP plane (APP) was defined, supine pelvic tilt was measured, and cup orientation was calculated by fitting a best fit plane to 6 points on the rim of the acetabular component. Cup orientation was calculated in degrees of operative anteversion and operative inclination according to the definitions of Murray. Both absolute cup position relative to the APP and tilt-adjusted cup position were calculated.Introduction
Methods
Cup malposition in hip arthroplasty and hip resurfacing is associated with instability, accelerated wear, and the need for revision. The current study similarly assesses the variation in cup position using conventional techniques as measured by CT. We have performed CT-based navigation of hip arthroplasty and revision arthroplasty on a routine basis since 2003 and also use CT imaging to quantify periprosthetic osteolysis. In our image database, we have identified 91 hips in 87 patients (51 female, 36 male) who had a previously conventionally-placed cup on CT imaging. For each hip, cup orientation was determined in operative anteversion and operative inclination (according to the definitions of Murray) using an application specific software application (HipSextant Research Application 1.0.7, Surgical Planning Associates Inc., Boston, Massachusetts). This application allows for determination of the Anterior Pelvic Plane coordinates from a 3D surface model. A multiplanar reconstruction module allows for creation of a plane parallel with the opening plane of the acetabulum and subsequent calculation of plane orientation in the AP Plane coordinate space.Introduction
Methods
Early rehabilitation and discharge following minimally-invasive total hip arthroplasty has potential risks including the possibility that patients may become progressively anemic at home. The current study assess the use of pre-emptive autologous blood transfusion on the length of stay, readmission, and allogenous transfusion. Patients treated by primary total hip arthroplasty using the superior capsulotomy technique were studied. Patients were divided into two groups. Group 1 were patients who did donate autologous blood and received an intra-operative pre-emptive transfusion. There were 283 patients in Group 1. Group 2 were patients who were medically capable of donating autologous blood but did not for non-medical reasons. There were 71 patients in Group 2. Patients who did not donate autologous blood for medical reasons (preoperative Hgb less than 11.5, age over 80) were excluded. All patients received general anesthesia. Length of stay, allogenous transfusion and readmission were compared.Introduction
Methods
Half of all acetabular components placed using conventional methods are malpositioned1. The HipSextant™ Navigation System (Surgical Planning Associates, Boston, MA) is a mechanical navigation system, adjusted on a patient-specific basis, designed to achieve appropriate cup alignment as simply and rapidly as possible. The current study assesses the surgeon's ability to register and track the pelvis and align the cup using the system. A bioskills model pelvis (Pacific Research Laboratories, Inc., Vashon, WA) was prepared by placing screws to mark the anterior pelvic plane points and by inserting a long cup alignment pin, simulating a cup insertion handle, into the acetabulum. The bone model was then scanned using CT. The HipSextantTM Navigation System Planning Application was then used to plan the use of the HipSextant for the surgery. This is accomplished by creating a 3D model, designating the AP plane (marked by the screws), and then determining the HipSextant docking points. One of these three points is behind the posterior wall of the acetabulum (the basepoint). The second of these three points is on the lateral aspect of the anterior superior iliac spine. The third point, the landing point, is located on the surface of the ilium and equally distant from the other two points (Figure 1). The two protractors on the HipSextant planning application were then adjusted to be parallel with the cup alignment pin on the bone model. A surgeon and assistant were then asked to dock the HipSextant on the bone model and to visually align the direction indicator to be parallel with the cup alignment pin. The two protractor angles on the instrument were recorded. This allowed for calculation of error in operative anteversion and operative inclination between the plan and the actual alignment that was accomplished. Four pairs of surgeon and assistant each performed the docking and alignment procedure 10 times for a total of 40 measurements.Introduction
Methods
The optimal goal for cup positioning in hip arthroplasty in individual patients is affected by many factors including surgical exposure, femoral anteversion, and pelvic tilt. Some navigation systems ignore pelvic tilt and are based strictly on the anterior pelvic plane while others incorporate pelvic tilt, as measured in the supine position on the operating table. Neither approach incorporates knowledge of preoperative spino-pelvic flexibility or predictions of the change in spino-pelvic attitude or flexibility following surgery. While prior studies have shown little change in pelvic tilt postoperatively, one recent study based on gait analysis, suggested that changes in pelvic tilt are not predictable. The current study aims to assess changes in pelvic tilt following surgery. 24 patients, 12 male and 12 female, underwent THA using CT-based navigation. Each patient had supine and standing AP pelvis radiographs both pre-operatively and at a minimum of 1 year post-operatively. Pelvic tilt on each radiograph was measured using a noncommercial two-dimensional/three-dimensional matching application. (HipMatch; Institut for Surgical Technology and Biomechanics, Bern, Switzerland). This software application uses a fully auto- mated registration procedure that can match the three- dimensional model of the preoperative CT with the projected pelvis on a postoperative radiograph. This method has been validated and for measurement of cup position for example showed a mean accuracy of 1.7° +/− 1.7° (rang-4.6° to 5.5°) in the coronal plane and 0.9° +/− 2.8° (rang-5.2° to 5.7°) in the sagittal plane compared with postoperative CT measurements. The software showed a good consistency with an intraclass correlation coefficient (ICC) for inclination of 0.96 (95% confidence interval [CI]: 0.93 to 0.98) and for anteversion of 0.95 (95% CI: 0.91 to 0.98). A good reproducibility and reliability for both inclination and anteversion was found with an ICC ranging from 0.95 to 0.99. No systematic errors in accuracy were detected with the Bland- Altman analysis. Using the HipMatch 2D/3D application, changes in pelvic tilt before and after surgery were assess in both the supine and standing positions.Introduction
Methods
