Pain relief in hip arthroplasty plays an important role in the intra/post operative stages in order to achieve an almost pain free post operative recovery period to mobilise the patient as early and safely as possible and avoid undesirable post surgical complications.

A consecutive series of 99 total hip arthroplasties in 93 patients performed by a single surgeon between December 1996 and January 2006 were assessed for signs of clinical or radiological loosening.

Intra-operative local anaesthetic mixture (Ropivacaine-Ketorolac (30mg) -Adrenaline or RKA mixture) was infiltrated into the joint capsule and surrounding tissue around the acetabular component, and into the different muscle layers in the thigh around the femoral component. A total of 150–200 mls of this mixture was injected and a further 50 mls (with 30mg ketorolac) injected through a catheter left in-situ before discharge 12 to 24 hours later. Radiographic analysis was carried out using the Hodgkinson criteria to predict acetabular component loosening and the Gruen method to determine femoral component loosening.

Of the 99 hybrid hips, 57 were right and 42 were left hip arthroplasties and 6 patients had bilateral consecutive hips done. 5 were performed for revision of fractured necks of femur in Birmingham hip resurfacings and one total hip arthroplasty revised to a hybrid and the remaining 92 were primary hybrid hip arthroplasties. The arthroplasties were performed for Osteoarthritis (89), Rheumatoid arthritis (4), and others (6). At mean follow up of 4.2 years, no aseptic loosening was noted radiologically or clinically, no components have been revised for failure or loosening and no components have dislocated.

The use of high dose local infiltration NSAIDs in the intraoperative and early post operative phase does not seem to affect prosthetic fixation at-least during short to mid term follow up of total hip joint arthroplasties.

This bone preserving procedure is less well described in the much older population over 65 years of age. Despite good bone quality, independence and active lifestyle, older age seems to be a deterrent for hip resurfacings among most orthopaedic surgeons.

Analysis of 111 Birmingham hip resurfacings in 105 consecutive patients from 1999 to 2007 performed by a single surgeon was carried out to determine radiological and clinical outcome. The unique selection criteria looked at joint disease, activity levels, general health, imaging (Xray/CT/MRI) and Bone density studies.

28 females and 77 males with mean age of 69.5 years (65–87 years, SD +/− 4), body mass index of 27.2 (19–40.4, SD +/− 3.8) underwent resurfacings. 8 patients had bilateral, consecutive 2 stage procedures. Mean Follow up was 3.8 years ranging from 3 months to 7 years. 62 resurfacings were performed in the age group 65–69 yrs, 32 resurfacings in the 70–74 age group, 12 resurfacings in the 75–79 age group and 4 resurfacings in the 80–89 age group. 77 patients (71.3%) stayed one night or less in hospital. 4 patients (3 males and 1 female) had postoperative fracture neck of femora.

Radiographic review at the most recent follow up revealed non of the patients (101) who had the original hip resurfacing components had any evidence of gross loosening, migration or subsidence requiring revision of either the cup or the femoral components. No patients complained of localised hip pain and at the most recent follow up they had very good to excellent function with no report of dislocations.

Hip resurfacing is a challenge in patients who are over the age of 65 years. Using our selection criteria, it may be offered to active, independent patients with good bone quality as this age group in the population becomes larger with time.

Birmingham Hip resurfacings have been a popular mode of treatment for younger and more active patients with arthritis of the hip. However the use of hybrid hip arthroplasty system with a Birmingham hip resurfacing cup and modular head with a variety of cemented/uncemented stems is less well described in the literature.

We analysed radiographic and clinical outcomes of 99 consecutive hybrid hip arthroplasties performed by a single surgeon between 2000 and 2006.

A total of 93 patients (52 females and 41 males) with an average age of 69.9 (47 to 88) and average BMI of 28.8 (18.7 to 140.9) had arthroplasties with a mean follow up of 4.1 Yrs (1 to 6.3 years). 57 right and 42 left hip arthroplasties were performed of which 6 patients had bilateral consecutive hybrid hip arthroplasties.

93 were performed for osteoarthritis, 4 for RA, 5 patients for revision of failed hip resurfacing arthroplasties with #NOF and 1 revision for failed THR.

No patients had dislocations and one patient had revision of a resurfacing cup secondary to hip pain due to excessive cup anteversion, no loosening of components were identified at the most recent follow-up and all patients were mobilising well with no complaints of pain.

Hip Resurfacing procedures are gaining popularity in the younger individuals with arthrosis of the hip. Some patients who are fairly independent and active fall short of satisfying the criteria for a hip resurfacing and we preferred the option of the Birmingham hip resurfacing cup with a large modular head and a compliment of stems. This metal-on-metal option with large heads would ideally increase stability and reduce wear patterns with the prospect of increasing longevity of total hip arthroplasties.

Introduction: Cemented hip resurfacing component orientation may, in part, be associated with femoral neck fracture. Orientation offset may be introduced due to the cement setting prior to achieving a completely seated component. Varus/valgus orientation error may occur due to surgical error or poor instrumentation design. We modeled a number of different orientations and investigated bone mineral density change using the finite element method.

Methods: CT scans were used to reconstruct the femoral geometry and create a finite element model. The boundary conditions applied were hip muscle forces at the 45% position of the gait cycle. Two models were created, a preoperative (reference) and a postoperative (reconstructed) model. The post operative model was reconstructed using the Birmingham Hip Replacement (BHR). Implant offsets and varus/valgus orientations were analysed. The bone mineral density (BMD) changes at nine positions along the superior and inferior aspects of the alignment stem were analyzed.

Results: Results suggest bone loss decreases with increasing offset distances. Femoral offset distance is defined as the perpendicular distance from the center line of the femoral shaft to the center of the femoral head. Greater femoral stem offsets increases the abductor moment arm and this decreases the abductor force need for walking as well as the overall articulating reactive force at the articulating surface. As the BHR orientation deviates away from the an extreme valgus to a more varus position, the volume of bone that will decrease in BMD increases.

Discussion: There is minimal difference between the 1mm and 3mm offsets and their respective bone remodeling volumes. The 5mm offset has a larger bone volume where the BMD will increase; this is due to the larger moment applied to the proximal femur and is not an advisable surgical position as there may be a large density gradient at the mouth of the resurfacing component and could predispose the femoral neck to fracture. There is also not a lot of difference in bone remodeling volume between the extreme valgus, 5° and 10° cases. However, the extreme valgus case does present a “notching” risk. The objective of this study was to implement a consistent theoretical adaptive bone remodelling rule that may, in part, give an understanding as to how a femoral resurfacing component’s orientation would influence and simulate BMD changes in the proximal femur.

Introduction: The process of impacting cemented hip resurfacing components may, in part, be associated with femoral neck fracture. The impaction process may introduce fractures due to the impact shock wave passing through the bone during the setting of the implant and achieving a completely seated position. The aim of this study was to measure the impaction loads during hip resurfacing surgery and correlate the measured loads to theoretical calculations.

Methods: Following ethical approval 3 patients have been enrolled out of 24 patients in a pilot study. A surgical mallet was manufactured and instrumented with a calibrated impact load cell. During the impaction procedure the impact loads are recorded to a laptop using Labview software. An Excel spreadsheet has been written using the finite difference method to calculate the impact loads based on a mass (hammer, impactor and implant) and spring system (compression only) defining each part of the surgical instrumentation used to impact the resurfacing component onto the femoral head.

Results: Clinically, upto 19 impacts are used to seat the resurfacing implant onto the femoral head. Loads upto 24kN were recorded. The finite difference model was calibrated to the clinical measurements. The Pearson’s R correlation coefficient for the net force on the mallet was 0.91 and for the impulse was 0.98

Discussion: This study has investigated the clinical impaction loads imparted onto an implant during resurfacing surgery and developed a finite difference model of the process. The finite difference approach can be used to better understand the loads applied to not only the implant, but the underlying bone. This may, in part, give the surgeon a better understanding as to whether the bone has been predisposed to fracture following the high impact loads and thereby affecting the long-term integrity of the joint replacement.

Introduction This prospective outcome study presents the results and complications of 41 lateral unicompartmental knee joint replacements.

Methods One surgeon operated on all the patients in this series. The surgery was performed through minimally invasive techniques wtih the patients being day-stay or overnight stay patients. Assessment was made using SF-36 and WOMAC questionnaires, physical examination, x-ray pre-operatively and at six monthly intervals. Kaplan-Meier survival analysis was carried out.

Results Forty-one knees (39 patients) underwent surgery. There were 15 males (average age 64 years) and 26 females (average age 68 years). Mean follow-up time was 3.2 years (max 4.6 years). Of these four were Repicci inlay components, 10 were Repicci onlay components and 28 were Oxford mobile bearing implants. Three patients required reoperation, all having mobile bearings in place. One required revision to total knee replacement for progression of arthritis in the medial compartment, and two for bearing dislocation. The operation consisted of a change of bearing to a thicker one. One of these patients had a further complication, a deep infection which was treated successfully with arthroscopic debridement and antibiotics. Another of the mobile bearing patients had a DVT. WOMAC and SF36 show a reduction in pain and stiffness, and an increase in physical function and quality of life. Kaplan-Meier analysis shows 100% survival of the fixed implants but 96% in the mobile bearing group. However 11% of the mobile bearing group required reoperation.

Conclusions Lateral compartment replacement is a technically demanding procedure. This study looks at the early results, and does not examine long-term wear. A significant difference in the complication rates for the different type of implant is noted, with the mobile bearing having a higher reoperation rate.

In relation to the conduct of this study, one or more of the authors is in receipt of a research grant from a non-commercial source.

Introduction: Bone fragility is a result of the reduction in bone mineral density and mass. This reduction directly reduces the effectiveness of trabecular cross bracing. The problem of femoral neck fractures after hip resurfacing surgery is directly related to the mechanical load on the osteoporotic bone.

Aim: To determine any correlation between the degree of osteoporous and subsequent femoral neck fractures.

Methods: A comparison was made between both femoral necks in the same patient, to determine the degree of osteoporosis prior to surgery. These results were then compared with subsequent changes in osteoporosis 12 months post-operatively.

Bone mineral density values, were used to compare the non-operative femoral neck to the operative femoral neck before surgery. These values were then used as a predictive risk of subsequent femoral neck fracture in this patient group. Bone mineral density assessments were repeated 12 months after the surgery to compare the subsequent changes in the osteoporotic values. The bone mineral density evaluations were carried out on one hundred patients, both male and female between the ages of 28 and 87 years. The criterion for entry into this group was a bone mineral density value of no lower than 1.5 standard deviation points below the young reference value.

Results: We found an improvement in the bone mineral density values for each patient, therefore reducing the risks of subsequent femoral neck fracture.

Aim: To assess the survival rate of implants and the effect of UKR on knee pain, function, stiffness and quality of life in a prospective study.

Methods: All of the knee replacements were performed using minimally invasive techniques. SF36 and WOMAC were evaluated pre-operatively and at six-monthly intervals post-operatively.

Results: There were 506 knees. The mean post-operative evaluation time was two years and six months and the maximum time was three years and nine months. The status of all knees was established. There were nine failures as determined by the need for revision procedures. Six patients died with their implants functioning.

Survival analysis: 99% at 12 months 98% at 24 months 98% at 36 months.

The scores on SF36 and WOMAC were adjusted to the Australian Population Norm. The WOMAC score showed an increase in function, and a decrease in the pain and stiffness scores. The physical and mental component summaries of the SF-36 both indicated an increased quality of life post-operatively. Implant failure was due to loosening of tibial and femoral components and progression of arthritic changes in the lateral compartments.

Conclusion: The results from the health assessment forms indicated a high patient satisfaction with the operation and a sustained improvement in quality of life, flexibility and function.

Introduction: Medial unicompartmental knee replacement (UKR) is a successful procedure in the management of early osteoarthrosis. This procedure is not usually indicated in patients who have insufficiency of the anterior cruciate ligament (ACL). However, a problem arises when, after a UKR, an ACL rupture occurs, and instability develops. A technique is described to stabilise the knee and possibly avoid conversion to total knee replacement.

Methods: Three patients underwent arthroscopic ACL reconstruction. Only semitendinosus tendon was used. The proximal fixation was with a Mulch screw (Biomet) and the distal fixation was with two screws and washers. A post-operative, standard, accelerated rehabilitation programme was used in all three.

Results: After two years, two patients continued playing doubles tennis, and one continued as a dancing instructor.

Conclusions: While an ACL-related instability is a contraindication to undertaking a UKR, the disruption of an ACL in a well functioning UKR and the development of instability need not necessarily force the conversion to TKR. Using a modified hamstring reconstruction it was possible to stabilise the knee and maintain the UKR function.

Introduction: Whether or not to resurface the patella in total knee replacement (TKR) is controversial. One concern is the possibility of progression of the arthritis in the patellofemoral joint that has not been resurfaced when exposed to the stress of articulating with the femoral component.

Methods: The cohort comprised six knees for Trac TKA (Biomet). The assessment involved the use of an electronic sensor system(Iscan, Tekscan). The readings were taken on an anaesthetised patient, during surgery. A tourniquet was not used. A subvastus operative approach was used.

Results: The contact area and contact stress increased with flexion with and without the femoral component in place. We measured no increase in patellar stress when the patella that had not been resurfaced articulated with the femoral component.