Introduction: Complications following hip resurfacing (HR) occur primarily because of the surgeon’s inability to achieve optimal implant positioning, and the significant learning curve associated with this demanding procedure. Our study sought to look at the impact of navigation technologies on this learning curve.

Materials and Methods: Twenty medical students doing their BSc project took part in the study. Four types of synthetic femurs were used for the study viz., Normal anatomy (11students), Osteoarthritis (5), Coxa Vara and Coxa Valga(2). Each student was allowed to insert the guide wire according to their judgement in the femoral head using 3 systems:

Conventional instrumentation,

This achieved angle was then compared with the angle originally planned for each bone in all three groups using digitizing arm.

Results: The range of error using the conventional method to insert a guide wire was 23deg (range −9 to 14, SD= 6.3), using the CT plan method, it was 22 deg (range −9 to 13, SD=6.6). Using the Navigation method it was 7 deg (range −5 to 2, SD=2.). Students who progressed from conventional through planning to navigation (group 1) were no more accurate than students who went straight to navigation without ever having used conventional instrumentation (group 3). Students produced similar accuracy even in their maiden attempt, on difficult anatomy when provided with navigation technology.

Discussion & Conclusion: This study has shown that motivated and enthusiastic students can achieve an expert level of accuracy very rapidly when provided with the appropriate level of technology. he development of surgeons who are able to deliver excellent outcomes depends more on technology than training.

Introduction: The development of the ilioinguinal approach by the pioneering work of Letournel in 1965 has transformed the treatment of acetabular fractures. To date, this approach has been well established and few modifications have been described of the original approach. However, this approach is difficult, takes long time for exposure and closure of abdominal layers. The aim of this article is to report a modification of the approach which the authors have found particularly useful.

Material and Method: Cadaveric dissection showed that it was easier to detach the inguinal ligament from the anterior superior iliac spine and reflect the anterior abdominal wall as one layer, than by the classical approach through layers of the anterior abdominal wall. Closure was also simpler, in the cadaver, with the entire anterior abdominal wall reattaching satisfactorily by a single transosseous suture. The rest of the approach, including division of iliopectineal fascia and developing the three windows remains the same as in the original approach.

Results: To date, three acetabular fractures have been reduced and fixed using this modification. Besides substantially speeding up the exposure and closure, this approach allows superior distal visualization of the anterior column and wall, and the impression of rather less bleeding. No complications developed with the three cases treated through this modified approach, and specifically, there have been no hernias, nor has the lateral femoral cutaneous nerve of the thigh been damaged.

Discussion: This small study demonstrates a modification to a classic approach that seems to be both safe and fast We hope that further experience will also show reduction in problems associated with wound healing. Further work in progress may also show that femoral venous flow is less impeded by this approach as retraction is not against the unyielding inguinal ligament.

Various frames of reference are routinely used for hip and knee arthroplasty. We hypothesised that the linea aspera is a constant anatomical feature which can be used as a frame of reference.

Twenty cadaveric femora were CT scanned with high resolution 1mm slices. Robin 3D software was used to manipulate the CT data. Three points were identified on the posterior aspect of the lesser trochanter, medial and lateral femoral condyles to position the femora in similar positions based on the posterior femoral plane (PFP). Centres of the femoral head and neck were derived by surface markers placed on the head and around the neck respectively. Joining the 2 centres gave head neck axis (HNA). The most prominent point on the linea aspera was identified at a level midway along the length of the femur. At that level the centre of the canal was derived by placing surface markers. Joining the most prominent point on the linea aspera to the centre of the canal identified our plane, linea aspera – centre plane (LCP). Angle measurements were made between PFP to HNA, PFP to LCP and LCP to HNA.

PFP to HNA is the traditional method for measuring anteversion angle which in our series had a mean of 13°, SD of 5 (range 5–24). PFP to LCP gave very similar results with mean 101°, SD 6 (range 92–112). However it was noted that there is weak correlation between PFP to HNA angle and PFP to LCP angle for each femur. LCP to HNA measurements were more variable with mean 89°, SD 8 (range 76–108).

From these data we conclude that the proximal half of the femur has more variable torsion compared to the distal half. This study shows that the linea aspera should not be used as a frame of reference for hip nor knee arthroplasties. However, further studies are needed to evaluate the linea aspera in-vivo where it is expected to be more prominent and easier to identify.

The use of intramedullary column screws in the treatment of acetabular fractures is becoming more widely utilized. The development of percutaneous methods to insert these screws under image intensifier guidance is one of the main reasons for their increased use. Few groups are navigating insertion of these screws. The available screws are cannulated 6.5–8 mm screws. Most surgeons prefer using 3.2 mm guide wires to reduce deflection. With a shank diameter of 4.5 mm, 3.2 mm cannulation significantly weakens the screws. We postulated that both columns, specially the posterior column can accommodate larger screw diameters which will increase the stability of fixation allowing earlier full weight bearing. The currently used screws were designed for fixation of femoral neck fractures. As percutaneous fixation of acetabular fractures is a growing area of interest, this warrants designing suitable screws with larger diameters.

Eight CT scans of the adult pelvis –performed for non fracture related indications-, were studied (7 females, 1 male). We found that the anatomical cross-section of the columns is irregular but approximately triangular. The method we used to determine the largest diameter of a screw to fit each column was fitting cylinders in the columns. Robin’s 3D software was used to segment acetabula and convert the CT data into polygon mesh (stereolithography STL format) bone surfaces at an appropriate Hounsfield value. The resulting STL files were imported in Robin’s Cloud software, where polygon mesh cylinders of 10 mm diameter were fitted in each column. These cylinders were then manipulated to achieve best fit and their diameters were gradually increased to the biggest diameter which still fitted in the column.

The mean diameters of the fitted cylinders were 10.8 mm (range: 10–13mm) and 15.2 mm (range 14–16.5mm) for the anterior and posterior columns respectively.

To our knowledge, this is the first investigation to study the cross sectional dimensions of the anterior and posterior columns of the acetabulum. Our small sample shows that both columns can safely accommodate larger screws than those currently used. We plan to investigate this further using cadavers.

Various frames of reference are routinely used for hip and knee arthroplasty. We hypothesised that the linea aspera is a constant anatomical feature which can be used as a frame of reference.

Twenty cadaveric femora were CT scanned with high resolution 1mm slices. Robin 3D software was used to manipulate the CT data. Three points were identified on the posterior aspect of the lesser trochanter, medial and lateral femoral condyles to position the femora in similar positions based on the posterior femoral plane (PFP). Centres of the femoral head and neck were derived by surface markers placed on the head and around the neck respectively. Joining the 2 centres gave head neck axis (HNA). The most prominent point on the linea aspera was identified at a level midway along the length of the femur. At that level the centre of the canal was derived by placing surface markers. Joining the most prominent point on the linea aspera to the centre of the canal identified our plane, linea aspera – centre plane (LCP). Angle measurements were made between PFP to HNA, PFP to LCP and LCP to HNA.

PFP to HNA is the traditional method for measuring anteversion angle which in our series had a mean of 13°, SD of 5 (range 5–24). PFP to LCP gave very similar results with mean 101°, SD 6 (range 92–112). However it was noted that there is weak correlation between PFP to HNA angle and PFP to LCP angle for each femur. LCP to HNA measurements were more variable with mean 89°, SD 8 (range 76–108).

From these data we conclude that the proximal half of the femur has more variable torsion compared to the distal half. This study shows that the linea aspera should not be used as a frame of reference for hip nor knee arthroplasties. However, further studies are needed to evaluate the linea aspera in-vivo where it is expected to be more prominent and easier to identify.

To assess the performance and success of joint sparing limb salvage surgery in high grade malignancy, in terms of function, complications, recurrence and survival, as compared to joint resection.

We report a ten-year experience of twenty patients with high grade malignancies of bone which did not cross the epiphyseal plate. They underwent not only limb salvage surgery but also joint preservation. The aim of this is to preserve function in the joint and to prevent the inevitable wear of prosthetic joints requiring revision surgery. The age range was 4 - 25 years (mean 13. 5). The Diagnoses were 14 Osteosarcomas and 6 Ewings sarcomas. Mean follow up was 49 months. There were 13 femoral & 7 tibial malignancies. 12 underwent complex biological fixation with a combination of reimplanted autoclaved or irradiated bone; vascularised fibular graft; femoral or humeral allograft. In 8 cases custom made hydroxyapatite coated prostheses were used to replace the resected bone. This surgery must clearly be evaluated in the context of recurrence, particularly as this is associated with an increased risk of metastases and death. Analysis of our results to date has not shown a greater rate of complications. We experienced one recurrence, and one death. The custom prostheses group had fewer complications and operations. Functionally these patients report near normal limbs and joints and do not report any limitation of activities.

Joint sparing limb salvage surgery is extremely worthwhile as it produces a significantly better functioning limb and lower morbidity, with less likelihood of revision surgery. We have not found a higher risk of post-operative complications, recurrence or death. Furthermore massive prosthetic replacement is quicker, osseointegrates reliably and is associated with a lower complication and further operation rate.