This Blinded Randomized Clinical Trial outlines: how peri-articular intra-operative multimodal analgesia significantly reduces post-operative analgesia requirement. Sixty-four patients undergoing total knee replacement were randomised to receive a peri-articular intra-operative injection containing ropivacaine, ketorolac, epimorphine and epinephrine or nothing. Patients who received the injection demonstrated greater satisfaction and pain relief. Finally, patients in the injected group did not show any signs of cardio and central nervous system toxicity.

Post-operative analgesia can be associated with troublesome side effects. Good peri-operative analgesia facilitates rehabilitation, improves patient satisfaction and may reduce hospital stay. The purpose of this study was to assess a novel cocktail for peri-articular analgesia after total knee replacement.

Sixty-four patients undergoing total knee replacement were randomised to receive a peri-articular intra-operative injection containing ropivacaine, ketorolac, epimorphine and epinephrine or nothing. The anaesthetic analgesic regime was standardised. All patients received patient controlled analgesia (PCA) for twenty-four hours post surgery, followed by standard analgesia. VAS pain scores during activity and at rest and patient satisfaction scores were recorded pre and post operatively and at six week follow up. PCA consumption and overall analgesic requirement were measured.

PCA use at six, twelve and over twenty-four hours post surgery was significantly less in patients receiving the injection (p< 0.01, p=0.016, p< 0.01). Patient satisfaction in PACU and four hours post operation was greater (p=0.016, p=0.013). VAS for pain during activity in PACU and at four hours were significantly less (p=0.04, p=0.007) in the injected group. The average ROM at six weeks was no different. Overall hospital stay and the incidence of wound complications were not different between the two groups.

Peri-articular intra-operative multimodal analgesia significantly reduces post-operative analgesia requirement. Patient satisfaction and pain relief is greater in the injection group. No cardio and central nervous system toxicity was observed.

Our novel cocktail of ketorolac, epimorphine, epinephrine and ropivacaine provides superior pain relief with no adverse side effects.

Despite favourable wear characteristics of compression molded HMWPE in vitro preliminary data show no statistical difference in wear between RAM extruded HMWPE and compression moulded polyethylene. This study reviews AP and lateral radiographs for wear using the Martell technique at two, five years and maximum follow up (mean 88.2 months).

Reduced implant survivorship due to aseptic loosening has prompted research into alternative bearing materials. Simulator testing is useful but clinical studies are the gold standard to evaluate the wear characteristics of new bearing materials.

On hundred and twelve patients matched for sex, age, body mass index, primary pathology, Charnley grade, and follow up underwent uncemented total hip replacement using an identical implant. Group One (sixty-four patients) had a RAM extruded liner (GUR 4150 HP) and Group Two (forty-eight patients) had a compression molded liner (Montell H 1900). HMWPE sterilisation regimes were identical. AP and lateral radiographs were analysed for wear using the Martell technique at two, five years and maximum follow up (mean 88.2 months).

Preliminary data show a linear and volumetric wear rate in Group One of 0.067 mm/yr and 26 mm3/year respectively between two years to maximum follow up. Similarly, the wear rates for Group Two were 0.132 mm/yr and 45 mm3/year respectively. There was no statistical difference in acetabular osteolysis between Group One (16.3%) and Group Two (15%) patients at maximum follow up.

Despite favourable wear characteristics of compression molded HMWPE in vitro preliminary data show no statistical difference in wear between RAM extruded HMWPE and compression moulded polyethylene. Quality of the wear debris is more likely to be important in producing aseptic loosening than actual wear rate.

Purpose: To assess the clinical utility of a computer-based program (discrete dynamic contour method of boundary refinement; Matlab®) to quantify the location and extent of periprosthetic osteolysis around cemented total knee arthroplasties.

Methods: The radiographs of 171 primary Anatomical Modular Knee arthroplasties were reviewed by three independent, blinded raters using Matlab® software program. The location, size (mm2), polyethylene sterilization technique, alignment, presence or absence of femoral osteolysis and patient characteristics was recorded.

Results: The mean duration of follow-up was 8.47 ± 1.10 years with minimum in vivo wear interval= 2.0 years. The overall incidence of radiographically apparent osteolysis was estimated at 30.41%. Furthermore, the average intra-class correlation coefficient for this measurement technique for three independent observers was found to be significant for medially and laterally located zones of osteolysis (I.C.C. value = .7801; 95% C.I. = .7161–.8316; (p< .05). There was a statistically significant trend towards higher rates of osteolysis occurring within the series of polyethylene inserts gamma irradiated in air. Lowest rates of osteolysis were measured in the series sterilized in gas plasma (27.09 mm2 per year vs. 16.24 mm2 per year respectively; p< .001).

Conclusions: The Discrete Dynamic Contour method of boundary refinement represents an acceptably reliable means by which one can quantify the location and extent of osteolysis based upon digitalized radiographs of total knee replacements.

Purpose: Post-operative analgesia using opioids or epidural analgesia can be associated with troublesome side effects. Effective peri-operative analgesia facilitates rehabilitation, improves patient satisfaction and may reduce hospital stay. Locally administered analgesia is effective, avoids systemic drug related side-effects and may be of benefit in minimally invasive joint replacement. This study compares the effects of a peri-articular injection cocktail in patients undergoing total knee and hip replacement surgery

Methods: 128 patients undergoing total knee (TKR) and hip (THR) replacement were randomised to receive a peri-articular intra-operative injection containing ropivacaine, ketorolac, epimorphine and epinephrine or nothing. The anaesthetic analgesic regime was standardised. All patients received patient controlled analgesia (PCA) for 24 hours post surgery, followed by standard analgesia. VAS pain scores during activity and at rest and patient satisfaction scores were recorded pre and post operatively and at 6 week follow up. PCA consumption and overall analgesic requirement were measured.

Results: Both TKR and THR patients used significantly less PCA 6 hours after surgery (p = 0.02 THR, p< 0.01 TKR). TKR patients receiving the injection used significantly less PCA use over 24 hours post surgery (p = 0.013). VAS for pain at 4 hrs post operation was significantly lower in the both groups (p = 0.003 TKR)(p = 0.017 THR). VAS for pain during activity at 24 hours was significantly less (p = 0.001) in the injected TKR group. Overall hospital stay and wound complications were not different between the groups.

Conclusions: Peri-articular analgesia significantly reduces post-operative analgesia requirement in TKR and THR patients. Greater satisfaction and pain relief was seen in TKR patients compared with THR.

Fifty-one prospectively followed Contour_ acetabular reconstruction cages, inserted through the direct lateral approach, were reviewed at three years minimum follow-up (range 3 to 6.4 yrs.). To date, four reoperations were required (two each for sepsis and instability) with no failures due to aseptic loosening. The Kaplan-Meier Survival Rate for any reoperation was 87% at 6.4 years. Short to mid-term follow-up of a single type of acetabular reconstruction cage, inserted through the lateral approach, demonstrated this to be a successful reconstruction option in the management of large acetabular bone defects.

This study reports the mid-term results of a single design of acetabular reconstruction cage inserted through the direct lateral approach.

At minimum three years follow-up (range 3 to 6.4 yrs.), there were no failures due to aseptic loosening with only four of fifty-one cases requiring reoperation (two sepsis, two instability).

This review supports the use of the reconstruction cage, inserted through the lateral approach, for large defects that cannot be managed with a hemispherical porous implant.

The use of the reconstruction cage in our center is reserved for large defects that cannot be managed with a hemispherical porous implant because of insufficient bone stock for initial implant stability and/or host bone contact for in-growth. Fifty-one consecutive prospectively followed Contour_ (Smith and Nephew) acetabular reconstruction cages, inserted through the direct lateral approach, were reviewed at three years minimum follow-up (range 3 to 6.4 yrs.). The majority of cases were AAOS Type Three and Four defects in which morsellized allograft was used in forty-nine cases and structural graft in three cases. Harris hip scores improved from 32.1±17.8 pre-op to 65.3±24.1 at most recent follow-up. Defining any acetabular reoperation as a failure, four of the fifty-one cages were considered to have failed giving a Kaplan-Meier Cumulative Survival Rate of 87% at 6.41 years. Two reoperations were for recurrent dislocation and the other two for sepsis. None of the fifty-one cages have been revised for aseptic loosening to date.

The timing of liner exchange for retroacetabular oste-olysis in THA remains uncertain. Liner exchange should be done before the shell becomes loose. The purpose of this study was to determine the radiographic quantity of osteolysis that will predict impending loosening of the cementless shell. Osteolytic lesions were quantified radiographically using three different measures. Implant stability was confirmed intraoperatively. Percent of shell circumference with surrounding osteolysis appears to be more predictive of cementless shell loosening than the area of osteolysis. When greater than fifty percent of the shell circumference has osteolysis on AP or lateral films, liner exchange is necessary.

The timing of liner exchange for retroacetabular osteolysis in cementless THA remains uncertain. Liner exchange should be done before the shell becomes loose.

To determine the radiographic quantity of osteolysis that will predict impending loosening of the cementless shell.

Osteolytic areas differ between loose and stable shells.

Between 1992 to 2002, seventy-one cementless shells of the same design were revised at our institution; forty-six were for aseptic retroacetabular osteolysis. Radiographs and a computer-assisted technique were used to quantify osteolytic areas and percent of shell circumference associated with lesions. Implant stability was confirmed intraoperatively.

Of twenty-six stable and twenty loose shells, the average area of osteolysis on AP radiographs showed no significant difference (Stable 591mm², Loose 630 mm², p greater than 0.05); whereas, lateral radiographs demonstrated a significant difference (Stable 546 mm², Loose 837 mm², p 0.05). The percentage of shell circumference with associated osteolysis on AP and lateral films demonstrated a significant difference (AP: Stable 60, Loose 75, p 0.042; LATERAL: Stable 49, Loose73, p 0.016). Diagnostic criteria of fifty percent shell circumference associated with osteolysis on AP films has sensitivity 1, specificity 0.27 while the same criteria on lateral films has sensitivity 0.84, specificity 0.54 for shell loosening.

Percent of shell circumference with surrounding oste-olysis appears to be more predictive of cementless shell loosening than the area of osteolysis. When greater than fifty percent of the shell circumference has osteolysis on AP or lateral films, liner exchange is necessary.

Introduction: Post-operative analgesia using parenteral opioids or epidural analgesia can be associated with troublesome side effects. Good peri-operative analgesia facilitates rehabilitation, improves patient satisfaction and may reduce hospital stay. Locally administered pre-emptive analgesia is effective, reduces central hyper-sensitisation and avoids systemic drug related side-effects and may be of benefit in minimally invasive joint replacement.

Materials and methods: 64 patients undergoing total knee replacement were randomised to receive a peri-articular intra-operative injection containing ropiva-caine, ketorolac, epimorphine and epinephrine. The anaesthetic analgesic regime was standardised. All patients received patient controlled analgesia (PCA) for 24 hours post surgery, followed by standard analgesia. VAS pain scores during activity and at rest and patient satisfaction scores were recorded pre and post operatively and at 6 week follow up. PCA consumption and overall analgesic requirement were measured.

Results: PCA use over 24 hours post surgery was significantly less in patients receiving the injection (P=0.013). Patient satisfaction at 4 hrs post operation was greater (P=0.003). VAS for pain during activity at 4 hrs and 24 hours were significantly less (P=0.001) in the injected group. The average ROM at 6 weeks was no different. Overall hospital stay and the incidence of wound complications was not different between the 2 groups.

Discussion: Peri-articular intra-operative multimodal analgesia significantly reduces post-operative analgesia requirement. Patient satisfaction is greater in the injection group. No cardio and central nervous system toxicity was observed.

Introduction and Aims: To compare the results of patients treated with articulating versus static antibiotic-impregnated spacers for infected knee arthroplasty.

Method: All patients undergoing two-stage revision knee arthroplasty for sepsis in the last five years were reviewed. Twenty-six patients had been treated with articulating spacers. This group was compared to 36 patients treated with static spacers. The articulating spacer technique had been adopted more recently than the static technique. Minimum follow-up was 12 months from second stage re-implantation (average 22 months articulating, 40 months static). Patients were compared in terms of the need for extensile exposures required for re-implantation, range of motion at most recent review, eradication of infection and augmentation required on revision implants.

Results: In the articulating group, fewer extensile exposure methods were required at second-stage prosthesis re-implantation (19% vs 36%). No tibial tuberosity osteotomies have been required since using the articulating spacer. The articulating group demonstrated a significantly improved range of flexion compared to the static group (106 vs 97 degrees – p=0.045) and had fewer patients with significant loss of extension or quadriceps lag. Eradication of infection was improved in the articulating group (92% vs 82%) but at shorter average follow-up. The need for augments and stabilised prostheses at revision surgery as a measure of bone loss was no different between the groups but was related to the number of prior surgical procedures.

Conclusion: Articulating cement spacers facilitate reimplantation surgery by maintaining tissue planes and joint mobility without compromising joint stability or eradication rate of infection. Patients demonstrate better range of motion and less complications related to the extensor mechanism with the articulated spacer.

Introduction and Aims: Cemented femoral revision total hip arthroplasty has been associated with early mechanical failure by aseptic loosening. This study was performed to determine the long-term survival of cemented femoral revision arthroplasty and to identify factors predictive of failure.

Method: One hundred and twenty-nine cemented femoral revision cases were reviewed to determine component survival. Ninety-seven hips with a minimum follow-up of five years were included for survival analysis and tests of significance. Harris hip scores were used to quantify clinical outcomes. Complete radiographic series were reviewed. Kaplan-Meier survival curves were calculated. Clinical and surgical factors were analysed to determine if they were predictive of failure.

Results: Individual Harris hip scores improved to a mean of 71 at the most recent follow-up from a mean pre-operative score of 52 (p< 0.001). Kaplan-Meier survival at 10 years was 91%, with revision for aseptic loosening of the femoral component as the endpoint and 71% with mechanical failure as the endpoint. Patients older than 60 years experienced greater long-term component survival and less pain than patients younger than sixty years (p< 0.05). Good quality post-operative cement mantles were associated with better long-term radiographic fixation (p< 0.001). Poor femoral bone quality was significantly associated with an increased rate of re-revision for aseptic loosening (p=0.021).

Conclusion: Revision femoral THA with cement remains an option in selected patients with acceptable 10-year survival and fair radiographic fixation. Patients demonstrated acceptable clinical outcomes at 10 years and few experienced significant pain. The best results may be achieved in older patients with adequate bone stock and modern cementing techniques.

Introduction and Aims: The use of porous coated femoral stems in revision hip arthroplasty has been associated with a high rate of complications including femoral fracture, femoral perforation and eccentric reaming. The purpose is to determine if using a distally slotted-fluted femoral stem is associated with lower incidence of the above three intra-operative complications.

Method: The intra-operative complications of 175 cementless revision total hip arthropasties (THA) using a distally slotted-fluted femoral stem were reviewed. Three categories of complications were recorded: femoral fracture, femoral perforation and eccentric reaming. Radiographic evaluation was based on standard antero-posterior and lateral views of the hip joint performed in the intra-operative or immediate post-operative period. Statistical analysis for factors associated with complications was performed using the chi-square test.

Results: Intra-operative complications occurred in 16 patients (9.1%). There was no statistically significant association between complication rate and type of surgical approach, stem length, stem diameter, or host bone quality. The complication rate was significantly lower than the 44% total complication rate previously reported utilising a long, solid, extensively coated revision stem without a slot or flute (p< .01). These results are consistent with laboratory testing, which revealed significantly lower bone strains at the isthmus when inserting a long cementless revision stem with a slot and flute compared to a solid fully coated stem of identical geometry.

Conclusion: The use of a distally slotted fluted porous coated femoral stem in revision hip arthroplasty results in a dramatically lower complication rate compared to rates previously reported for solid porous stems. These results strongly support the continued use of such a prosthesis for revision THA.

Introduction and Aims: Problem: The timing of liner exchange for retroacetabular osteolysis in THA remains uncertain. Liner exchange should be done before the shell becomes loose.

Purpose: To determine the radiographic quantity of osteolysis that will predict impending loosening of the cementless shell.

Hypothesis: Osteolytic areas differ between loose and stable shells.

Method: Between 1992 and 2002, 71 cementless shells of the same design were revised at our institution; 46 were for aseptic retroacetabular osteolysis. Radiographs and a computer-assisted technique were used to quantify osteolytic areas and percent of shell circumference associated with lesions. Implant stability was confirmed intra-operatively.

Results: Of 26 stable and 20 loose shells, the average area of osteolysis on AP radiographs showed no significant difference (Stable 591mm2, Loose 630 mm2, p greater than 0.05); whereas, lateral radiographs demonstrated a significant difference (Stable 546 mm2, Loose 837 mm2, p 0.05). The percentage of shell circumference with associated osteolysis on AP and lateral films demonstrated a significant difference (AP: Stable 60, Loose 75, p 0.042; LATERAL: Stable 49, Loose 73, p 0.016). Diagnostic criteria of 50 percent shell circumference associated with osteolysis on AP films has sensitivity 1.0, specificity 0.27, while the same criteria on lateral films has sensitivity 0.84, specificity 0.54 for shell loosening.

Conclusion: Percent of shell circumference with surrounding osteolysis appears to be more predictive of cementless shell loosening than the area of osteolysis. When greater than 50 percent of the shell circumference has osteolysis on AP or lateral films, liner exchange is necessary.

Introduction and Aims: The dilemma to retain or sacrifice the posterior cruciate ligament in a primary total knee arthroplasty continues to be an area of discussion. A randomised clinical trial was performed comparing clinical, radiographic and quality of life outcomes between patients receiving a posterior cruciate sparing versus posterior cruciate substituting knee implants.

Method: A multi-centred, prospective, randomised, blinded, clinical trial was performed to compare posterior cruciate retaining (CR) versus posterior cruciate substitution (PS) in osteoarthritic patients with an intact posterior cruciate ligament, undergoing total knee arthroplasty using the AMK^® (Depuy^®, Warsaw, Indiana) component. One hundred and fifty-two patients were randomised to receive one of the two devices. Patients were evaluated pre-operatively, at three, six, 12 months and annually thereafter. Patient demographics, radiographs, and multiple validated, outcome measures (WOMAC, SF-12, the Knee Society Clinical Rating System, and a stair climbing test) were evaluated. Patients and assessors were blinded to the implant design.

Results: One hundred and fifty-two patients were randomised at three centres; 72 in the CR group and 80 in the PS group. One patient was revised due to instability. Average follow-up was 5.14 years (range 2.97–6.99 years). There were no significant differences in baseline patient demographics between groups. There were no significant differences in outcome measures or radiographic findings. There were no significant differences in the Knee Society Clinical Rating System (CR- 159.18 versus PS- 156.49). There were no differences in knee extension at latest follow-up (CR- 1.02) and (PS- 1.10). There were no differences in knee flexion at latest follow-up (CR-111.00 ) and (PS- 113.61). No differences were noted in the WOMAC and SF-12 scores between the two groups.

Conclusion: In this prospective randomised clinical trial no significant differences involving radiographs and multiple outcome measures could be seen between a cruciate retaining versus a posterior stabilised total knee prostheses at a mean follow-up of 5.14 years. Long-term evaluation is necessary to comment on wear, osteolysis and implant longevity.

Introduction and Aims: Problem: Patellar resurfacing in TKA remains controversial. Purpose: To evaluate the results of resurfacing/non-resurfacing of the patella in a randomised controlled clinical trial at a minimum of 10 years of follow-up.

Method: One hundred knees (90 patients) with osteoarthritis were enrolled in a prospective randomised controlled double-blinded trial using the same posterior cruciate retaining total knee replacement. Patients were randomised to resurfacing or non-resurfacing of the patella. Evaluations were performed pre-operatively and yearly to a minimum of 10 years (range 10.1–11.5 years) postoperatively. Disease-specific (Knee Society Clinical Rating System), functional (stair climbing, knee flexion/extension torques, patellar examination) outcomes were measured. Patient satisfaction, anterior knee pain, and patellofemoral questionnaires were completed. Intra-operative grading of the articular cartilage was performed.

Results: No patients were lost to follow-up; 46 knees remained alive. Nine revisions (9/90–10%) were performed – 7/48 (15%) in the non-resurfaced and 2/42 (5%) in the resurfaced group. Three knees in the non-resurfaced group were revised to a resurfaced patella for anterior knee pain. One resurfaced patella was complicated by AVN and fracture, requiring revision. No significant difference was found between the groups regarding revision rates, KSCR score, functional, satisfaction, anterior knee pain, patellofemoral, and radiographic outcomes. Intraoperative cartilage quality was not a predictor of outcome.

Conclusions: This study represents the longest follow-up to date of a randomised controlled clinical trial to examine patellar resurfacing in TKA. The results showed no significant difference between the groups for all outcome measures at a minimum of 10 years.

Introduction and Aims: Polyethylene wear in total hip arthroplasty (THA) is frequently associated with wellfixed cementless implants. Purpose: To evaluate the clinical and radiographic results of the isolated liner exchange (ILE) procedure in revision THA via the direct lateral surgical approach.

Method: A prospective study of 24 hips that underwent an ILE revision procedure via the direct lateral approach was conducted. Accessible osteolytic lesions were managed with curettage and bone grafting. Clinical data including Harris hip score, WOMAC Index, SF-12, and radiographic analysis were recorded. The area of osteolytic lesions was calculated using a new software program.

Results: This is the first study to our knowledge to report on the results of the ILE procedure performed via the direct lateral surgical exposure. Twenty-three patients underwent 24 revisions with an ILE. At mean follow-up of 40 months, all osteolytic lesions had regressed. Harris hip scores improved from 69 to 83. WOMAC indices improved from 37 to 24. No dislocations have occurred. Two patients have required revision. Isolated liner exchange for polyethylene wear is a promising technique that avoids the removal of well-fixed acetabular implants. The increased dislocation rate associated with this revision THA procedure may be reduced and osteolytic lesions may be successfully debrided and bone grafted through the direct lateral approach.

Conclusion: The ILE procedure, when performed via the direct lateral surgical approach, may reduce the dislocation rate commonly reported via the posterolateral exposure with this procedure. Retention of well-fixed implants and bone grafting preserves bone stock and adequately addresses osteolytic lesions at revision surgery through this exposure.

Introduction and Aims: Polyethylene wear continues to be the most significant issue following total hip arthroplasty (THA), leading to the current increase in use of alternative bearing surfaces. We performed a prospective, randomised, blinded clinical trial comparing metal versus polyethylene bearing surfaces in patients receiving THA.

Method: Forty-one patients were randomised to receive a metal (23) or a polyethylene (18) insert with identical femoral and acetabular components. Patients were evaluated pre-operatively at three, six, 12 months and annually thereafter, including an evaluation of erythrocyte and 24-hour urine cobalt, chromium and titanium metal ion levels, validated outcome measures (WOMAC, SF-12, Harris Hip Score) and radiographs.

Results: No patients were lost to follow-up. One patient died of unrelated causes. At an average 4.4 (range 3.3–5.1) years follow-up there were no differences in any outcome measures or radiographic findings. Patients receiving metal liners had significantly elevated metal ion measurements. At the latest follow-up erythrocyte cobalt levels were seven times elevated (median 1.2μg/l (metal) Vs 0.18μg/l (poly), p< .001). Urine cobalt levels were 41 times elevated (median 11.9μg/day (metal) Vs 0.29μg/day (poly), p< .001) and urine chromium levels were 14 times elevated (median 4.9μg/day (metal) Vs 0.36μg/day (poly), p< .001). Erthrocyte chromium, titanium and urine titanium were not significantly different between groups. As well, contrary to previous reports, there was not a significant trend towards decreasing ion levels over time.

Conclusion: In this prospective randomised blinded clinical trail comparing metal to polyethyle bearing surfaces, both cobalt and chromium ion levels were significantly elevated in the blood and urine of the patients randomised to receive the metal on metal THA.

Introduction and Aims: While highly cross-linked polyethylene has achieved widespread clinical use based on laboratory testing showing significant wear reduction, there is little clinical information demonstrating its benefits in vivo. This study reports the early clinical and wear performance of a prospective randomised controlled trial comparing highly cross-linked to standard polyethylene.

Method: One hundred patients were enrolled in a prospective randomised controlled trial in which all patients received a hybrid THR (cemented Versys stem, Triology cementless acetabulum). The two groups were virtually identical in terms of age, weight, male/female ratio and received identical hip implants, except that one half (50 patients) randomly received a highly cross-linked polyethylene liner. Clinical outcomes were determined using Harris hip, WOMAC and SF-12 scores. Two-dimensional (2D) and three-dimensional (3D) wear rates were determined using a validated radiographic technique based on AP and lateral radiographs at six weeks and one, two and three years post-operatively.

Results: At two years minimum follow-up (range two to four years), there were no differences in Harris hip, WOMAC or SF-12 scores. No patients were lost to follow-up, although five patients had died of unrelated causes. There were no infections, dislocations or revisions to date. Wear analysis at one-year post-op showed high penetration rates for both groups (mean 3D wear approximately 0.25 mm/year) consistent with the bedding-in phenomena. At most recent radiographic follow-up (two or three years), there was a statistically significant although modest difference in wear rates between the two groups with a 2D and 3D wear rate of 0.14±0.10 mm/yr and 0.15±0.02 mm/yr respectively for conventional polyethylene compared to 0.09±0.04 mm/yr and 0.11±0.02 mm/yr for cross-linked polyethylene. This represented a 32 and 29 percent reduction in 2D and 3D wear rates respectively with cross-linked polyethylene.

Conclusion: At early follow-up, there were no clinical differences. There was a modest wear reduction (approximately 30%) with highly cross-linked polyethylene, considerably less than expected based on laboratory testing. Longer follow-up, after the bedding-in process is completed, is required to demonstrate the wear reduction afforded by highly cross-linked polyethylene.

Introduction and Aims: Fixed bearing and mobile bearing knee designs are currently used in clinical practice with little evidence based research available to determine superiority of one system. The purpose of this study was to compare the results between a cruciate retaining mobile bearing and two cruciate retaining fixed bearing total knee prostheses.

Method: We performed a prospective, randomised, blinded clinical trial to compare a mobile bearing to two standard fixed-bearing implants. We evaluated the short- and long-term outcomes of the SAL^® (Sulzer) mobile bearing versus the AMK^® (Depuy) and Genesis II^® (Smith & Nephew) fixed bearing, total knee joint replacements. Ninety patients were randomised to receive one of the three prostheses. Patients were evaluated pre-operatively, at three, 12 months and annually thereafter. Patient demographics, radiographs, and multiple outcome measures (WOMAC, SF-12 and the Knee Society Clinical Rating System) were evaluated. A single observer was used to measure range of motion scores.

Results and Discussion: No patients were lost to follow-up. One patient was withdrawn due to dementia before three months, one patient died prior to the two-year follow-up, and one patient was revised for infection at six months, leaving 87 patients at an average follow-up of 3.37 years (range 2.91–4.44 years). There were no significant differences in any outcome measures or radiographic findings. There were no differences in KSCRS at two years (SAL – 167, AMK – 158, GenesisII – 166 ). There were no differences in WOMAC scores or SF-12 survey scores. There were no differences in knee flexion at two years (SAL – 117^°, AMK – 115^°, GenesisII – 118^°). Therefore, no differences in multiple outcome measures were seen between a cruciate retaining mobile bearing and two cruciate retaining fixed bearing total knee prostheses.

Conclusion: In this prospective randomised clinical trial no differences could be seen between a mobile bearing and two fixed bearing designs at a minimum of two years follow-up. Long-term evaluation will be required to comment on differences in polyethylene wear and implant longevity.

Our aim was to evaluate the functional outcome of extensile revision knee exposure techniques.

166 revision total knee arthroplasties requiring an extensile exposure with 2 year minimum follow-up were prospectively studied {81 rectus snips (RS), 42 tibial tubercle osteotomies (TTO), and 43 quadriceps turn-downs (QT)}. Patients were clinically evaluated for knee society score, range of motion (ROM) and extensor lag comparing pre-op and 24 month follow-up appointment findings. Radiological evidence of avascular necrosis (AVN) pre & post operation was recorded. The TTO group was further examined for proximal migration of the tubercle post op.

Pre-operative knee motion (75° & 71°) and knee scores (74 & 70) were lower in revision total knee arthroplasties requiring QT & TTO than those requiring a RS (91° & 84). Post op flexion and knee scores were greater in the RS group (102° & 131) than in the QT (81° & 114) and TTO (84° & 111) groups in whom there was no significant difference. Avascular necrosis of the patella was most commonly seen following QT. In both QT & TTO groups performing a lateral release was significantly associated with AVN of the patella. Extensor lag (> 10°) was seen only in the QT & TTO groups (11% & 8%) in whom there was no significant difference. Tubercle escape (> 2mm) in the TTO group was significantly greater (54%) in those where circlage wires only had been used than in those where a proximal transfixation wire was used (11%).

In conclusion, both QT & TTO groups had similarly poor knee scores & ROM pre & post operation. AVN of the patella for both groups was similar and significantly associated with performing a lateral release. Finally we would conclude that the use of a through wire significantly reduces tubercle escape in TTO fixation.

We report on five-ten year results of AORI type two bone defects treated with modular augments in revision knee surgery.

102 revision knee arthroplasties with type two defects were treated with augments & stems and minimum five-year follow-up were prospectively studied.

15 patients (16 knees) died with retention of their prosthesis, 7 knees had incomplete follow-up. There were 79 remaining knees with complete follow-up of 7+−2 years (range: 5 – 11). The presence of non-progressive radiolucent lines around the augment in 20% of knees was not associated with poorer knee scores, range of motion, component survival or type of insert used (p> 0.05). Kaplan-Meier survival of the components was 92+− 0.03% at 11 years (95%CI:10.3–11.2)

We support the use of modular augmentation devices to treat type 2 defects in revision knee surgery and conclude that theoretical concerns of fretting and loosening based on 5 – 10 year clinical data are unfounded.

Aim: unicompartmental Knee Arthroplasty (UKA) is experiencing a resurgence in popularity. In order to provide accurate indications for UKA it is essential to evaluate the long-term results and to determine which patients are appropriate candidates.

Methods: One hundred and seventeen cemented UKA were performed between 1988 and 1995 in 90 patients with osteoarthrosis. The cohort comprised 25 Brigham (BG) and 92 Miller-Galante (MG) implants performed in a sequential fashion in well-matched groups. The average age at the time of the surgery was 66.4 years (range: 39.5 years to 87.1 years). There were 72 males and 45 females. The surgery was performed by either one of two surgeons. The minimum follow-up period was five years and the maximum was 13.2 years. Data, including KSCRS scores and radiographic results, were collected prospectively for all patients.

Results: Six Patients died during the study period and two were lost to follow-up. The average time of death was eight years post-operatively, with average latest KSCRS prior to death of 184 points compared with 134.7 pre-operatively. Twelve knees were revised at an average of 4.25 years (range 1.0 – 11.8 years) after the initial surgery, with polyethylene wear and progression of arthrosis being the most common reasons. The surviving 97 implants had an average follow-up of 9.6 years, with an average KSCRS improving from 100 points pre-operatively to 172 points at latest follow-up. There was no radiographic evidence of prosthetic loosening. A survival analysis using revision as the end-point (Kaplan-Meier, 95% confidence interval) showed a 10 year survival of 89% for all prostheses, 85% for BG, and 90% for MG prostheses.

Conclusions: Relatively few reports of the long-term results of UKA are available. The results of this study are slightly inferior but still comparable to TKA after the same follow-up period, suggesting that, with proper patient selection, UKA can offer reliable relief of pain and restoration of function for patients with unicompartmental knee osteoarthrosis.