Introduction. Acetabular component orientation is an important determinant of outcome following total hip arthroplasty (THA). Although surgeons aim to achieve optimal cup orientation, many studies demonstrate their inability to consistently achieve this. Factors that contribute are pelvic orientation and the surgeon's ability to correctly orient the cup at implantation. The goal of this study was to determine the accuracy with which surgeons can achieve cup orientation angles. Methods. In this in vitro study using a calibrated left and right sawbone hemipelvis model, participants (n=10) were asked to place a cup mounted on its introducer giving different targets. Measurements of cup orientation were made using a stereophotogrammetry protocol to measure radiographic inclination and operative anteversion (OA). A digital inclinometer was used to measure the intra-operative inclination (IOI) which is the angle of the cup introducer relative to the floor. First, the participant stated his or her preferred IOI and OA and positioned the cup accordingly. Second, the participant had to position the cup parallel to the anteversion of the transverse acetabular ligament (TAL). Third, the participant had to position the cup at IOI angles of 35°, 40° and 45°. Fourth, the participant used the mechanical alignment guide (45° of IOI and 30° of OA) to orient the cup. Each task was analysed separately and subgroup analysis included left versus right side and hip surgeons versus non-hip surgeons. Results. For the first task, hip surgeons preferred smaller IOI and larger OA than non-hip surgeons, but there was no significant difference in accuracy between both groups. When aiming for TAL, both surgeon groups performed similar, but accuracy on the non-dominant side was significantly better compared with the dominant side (mean deviation 0.6° SD 2.4 versus −2.6° SD 2.3) (p=0.004). When aiming for a specific IOI target of 35°, 40° or 45°, non-hip surgeons outperformed hip surgeons (mean deviation form target IOI 1.9° SD 2.7 versus −3.1° SD 3.8) (p<0.0001) with less variance (p=0.03). Contrary to version, accuracy on the dominant side was significantly better compared with the non-dominant side (mean deviation −0.4° SD 3.4 versus −2.1° SD 4.8). When using a mechanical guide, surgeons performed similar (0.6° SD 1.2 versus −0.4° SD 2.1 for inclination p=0.11 and −0.5° SD 2.6 versus −1.8° SD 3.3 for version p=0.22) and these values did not differ significantly from the actual IOI and OA of the mechanical guide. When using a mechanical guide, there was no difference in accuracy between the dominant and non-dominant side. Conclusion. There was no difference in accuracy between hip surgeons and non-hip surgeons when they aimed for their preferred IOI and OA or used a mechanical guide. When aiming for a specific IOI target, non-hip surgeons outperformed hip surgeons. Hip surgeons overestimate IOI and underestimate OA, presumably because this helps to achieve the desired radiographic cup orientation. Regarding accuracy, the non-dominant side was better for version and the dominant side for inclination. When aiming for a specific IOI and OA target, using a mechanical guide is significantly better than freehand cup orientation

Background. Accurate implant orientation is associated with improved outcomes after artificial joint replacement. We investigated if a novel augmented-reality (AR) platform (with live feedback) could train novice surgeons to orientate an acetabular implant as effectively as conventional training (CT). Methods. Twenty-four novice surgeons (pre-registration level medical students) voluntarily participated in this trial. Baseline demographics, data on exposure to hip arthroplasty, and baseline performance in orientating an acetabular implant to six patient-specific values on a phantom pelvis, were collected prior to training. Participants were randomised to a training session either using a novel AR headset platform or receiving one-on-one tuition from a hip surgeon (CT). After training, they were asked to perform the six orientation tasks again. The solid-angle error in degrees between the planned and achieved orientations was measured using a head-mounted navigation system. Results. Novice surgeons in both groups performed with a similar degree of error prior to training (AR: 14.2°±7.0°, CT: 15.7°±6.9° (p>0.05)). After training, average error was 10.7°±5.8° for AR participant and 7.2°±4.4° for CT participants. The average improvement per student was 3.5°±7.2° and 8.5°±8.0° respectively (p>0.05). Conclusions. A novel AR platform delivered training for acquiring skills to orientate an acetabular cup implant. After one session, novices trained by a hip surgeon outperformed those trained using AR. In both groups, accuracy remained below “expert” level proficiency (<5 degrees error). Further investigation is required to evaluate if novices retain skills, continue to improve with further training, and can transfer this to clinical practice

Total hip replacement (THR) is an option in a subset of patients with a neck of femur (NOF) fracture. The Scottish Intercollegiate Guidelines Network (SIGN) and National Institute for Clinical Excellence (NICE) provide guidance on the use of THR in patients with a NOF fracture. We compare our experience and recommend changes at a local level to allow successful implementation of the guideline to improve patient care. From July 2008 to July 2011, 36 THRs preformed for trauma were identified retrospectively by cross-referencing several databases (Bluespier, Worcestershire, UK and surveillance of Surgical Site Infection (SSI), Scotland). 7 exclusions (3 failed internal fixation, 1 chronic NOF fracture, and 2 extra-capsular fractures) leaving 29 patients. All operations were carried out under the supervision of a hip surgeon. Outcome data (see results) was collected from electronic sources. Statistical analysis preformed using Fisher's exact test for categorical data. Median age 62 years (44–88), time to surgery 4 days (2–8), American association of anaesthesia grade 2 (2–4) and hospital stay was 12 days (6–18). The first operator was a consultant in 23 cases and registrar in 6. 9 hips were cemented, 5 uncemented and 15 hybrid. 13 (44.8%) patients had a complication including 8 major (27.6%) complications. A blood transfusion was required in 11 (37.9%) patients. There were 2 (6.9%) deaths. A delay to surgery of more than 2 days was associated with increased risk of major complication (p< 0.03). ASA, Age, Grade of surgeon or Cement not associated with major complications. Our results are inferior to those in the literature. We have identified potential causes; mainly a delay to surgery increasing risk of major complication. In keeping with the current guidelines we recommend that local pathways are instigated to ensure THRs for trauma may be preformed in a timely fashion

Introduction. The purpose of this study was to evaluate the functional and radiographical results in patients younger than 30 years who underwent cementless third generation ceramic-on-ceramic total hip arthroplasty for osteonecrosis of the femoral head. Methods. Forty one patients (55 hips) who underwent total hip arthroplasty with third generation ceramic-on-ceramic bearings for osteonecrosis of the femoral head with a minimum 4-year follow-up were included in this study. There were 26 men and 15 women who had a mean age of 26 years (range, 16 to 29 years). The average duration of follow-up was 6 years (range, 4 to 7 years). All surgeries were done by a single hip surgeon and third generation ceramic-on-ceramic articulations were used. Securefit (Stryker) acetabular components were used in 46 hips and Duraloc (Depuy) in 9 hips. Accolade (Stryker) femoral stems were used in 33 hips, cone prosthesis (Zimmer) in 18 hips and CLS (Zimmer) in 4 hips. Functional results were measured by Harris hip (HHS) and WOMAC scores. Radiographic evaluation was assessed for loosening and osteolysis according to Gruen and Delee and Charnley criteria. Results. The average HHS improved from 53 points (range, 24 to 59 points) pre-operatively to 95 points (range, 88 to 100 points) at last follow-up. WOMAC scores improved from 72 points (range, 50 to 98 points) to 25 points (range, 21 to 37 points). Thirty nine patients (51 hips) continued their normal occupation. There was no aseptic loosening, osteolysis, and no prosthesis had been revised. There was one patient who complained of continuous squeaking and two patients with Brooker grade I heterotopic ossification. There were no other major complications such as ceramic fracture. Conclusion. Total hip arthroplasty with third generation ceramic-on-ceramic bearings for osteonecrosis of the femoral head especially in active and young patients resulted in satisfactory clinical and radiological results at minimum 4 year follow-up. If long-term follow-up shows excellent results, then the age limit for total hip arthroplasty might be lowered

Introduction. The purpose of this study was to evaluate the functional and radiographical results in patients who underwent a modified minimally invasive two-incision total hip arthroplasty using large-diameter ceramic-on-ceramic articulations for osteonecrosis of the femoral head. Methods. One hundred and one patients (135 hips) who underwent unilateral minimally invasive two-incision total hip arthroplasties using large diameter ceramic-on-ceramic bearings for osteonecrosis of the femoral head with a minimum 12-months follow-up were included in this study. There were 22 women and 79 men who had a mean age of 46 years (range, 22 to 82 years). The mean follow-up was 25 months (range, 12 to 36 months). All surgeries were done by a single hip surgeon. The authors modified the original minimally invasive two-incision total hip arthroplasty technique and used large-diameter (32mm, 36mm) ceramic-on-ceramic articulations. In the lateral position, an anterolateral approach between the gluteus medius and tensor fascia lata muscles and a posterior approach between the piriformis and gluteus medius muscles was used. Functional results were measured by Harris hip (HHS) and WOMAC scores. Radiographic evaluation was assessed for positioning of the components and complications were assessed. Results. The mean Harris hip score improved from 43 points (range, 13 to 58 points) pre-operatively to 96 points (range, 73 to 100 points) post-operatively and the mean WOMAC score improved from 67 points (range, 50 to 98 points) to 28 points (range, 26 to 39 points). On radiological evaluation, the mean lateral opening angle of the acetabular component was 35.9 degrees (range, 27.1 degrees to 47.4 degrees) and the mean stem position was valgus 2.4 degrees (range, varus 2.7 degrees to valgus 5.3 degrees). One patient suffered an intra-operative femur fracture and another underwent revision surgery due to stem subsidence. There were no complications such as immediate post-operative deep infection, delayed infection, or recurrent dislocation. Conclusion. A modified minimally invasive two-incision total hip arthroplasty using large-diameter ceramic-on-ceramic articulation for osteonecrosis of the femoral head is safe and reproducible in terms of achieving proper implant positioning and early functional recovery. In particular, the complication rates encountered, especially dislocation, were low

Interfacial defects between the cement mantle and a hip implant may arise from constrained shrinkage of the cement or from air introduced during insertion of the stem. Shrinkage-induced interfacial porosity consists of small pores randomly located around the stem, whereas introduced interfacial gaps are large, individual and less uniformly distributed areas of stem-cement separation. Using a validated CT-based technique, we investigated the extent, morphology and distribution of interfacial gaps for two types of stem, the Charnley-Kerboul and the Lubinus SPII, and for two techniques of implantation, line-to-line and undersized.

The interfacial gaps were variable and involved a mean of 6.43% (sd 8.99) of the surface of the stem. Neither the type of implant nor the technique of implantation had a significant effect on the regions of the gaps, which occurred more often over the flat areas of the implant than along the corners of the stems, and were more common proximally than distally for Charnley-Kerboul stems cemented line-to-line. Interfacial defects could have a major effect on the stability and survival of the implant.

We compared the orientation of the acetabular component obtained by a conventional manual technique with that using five different navigation systems.

Three surgeons carried out five implantations of an acetabular component with each navigation system, as well as manually, using an anatomical model. The orientation of the acetabular component, including inclination and anteversion, and its position was determined using a co-ordinate measuring machine.

The variation of the orientation of the acetabular component was higher in the conventional group compared with the navigated group. One experienced surgeon took significantly less time for the procedure. However, his placement of the component was no better than that of the less experienced surgeons. Significantly better inclination and anteversion (p < 0.001 for both) were obtained using navigation. These parameters were not significantly different between the surgeons when using the conventional technique (p = 0.966).

The use of computer navigation helps a surgeon to orientate the acetabular component with less variation regarding inclination and anteversion.

A complete cement mantle is important for the longevity of a total hip replacement. In the minimally-invasive direct anterior approach used at the Innsbruck University hospital, the femoral component has to be inserted into the femoral canal by an angulated movement. In a cadaver study, the quality and the extent of the cement mantle surrounding 13 Exeter femoral components implanted straight through a standard anterolateral transgluteal approach were compared with those of 13 similar femoral components implanted in an angulated fashion through a direct anterior approach. A third-generation cementing technique was used. The inner and outer contours of the cement mantles was traced from CT scans and the thickness and cross-sectional area determined.

In no case was the cement mantle incomplete. The total mean thickness of the cement mantle was 3.62 mm (95% confidence interval 3.59 to 3.65). The mean thickness in the group using the minimally-invasive approach was 0.16 mm less than that in the anterolateral group. The distribution of the thickness was similar in the two groups. The mean thickness was less on the anteromedial and anterolateral aspect than on the posterior aspect of the femur.

There is no evidence that the angulated introduction of Exeter femoral components in the direct anterior approach in cadavers compromises the quality, extent or thickness of the cement mantle.