Purpose

To determine if minimally invasive surgery (MIS) for primary hip replacement surgery increases the risk of long term aseptic loosening as predicted by implant micromotion measured with radiostereometric analysis (RSA).

Purpose

The purpose of this study was to assess the clinical outcomes over two years for total ankle arthroplasty (TAA) using Short Form-36, Foot Function Index and Ankle Osteoarthritis Scores, and to compare these with radiostereometric analysis longitudinal migration and inducible displacement results.

Purpose

The purpose of this study was to assess the biomechanical stability of the a total ankle arthroplasty system using longitudinal migration (LM) and inducible displacement (ID) measures. This study is the first study of its kind to assess total ankle arthroplasty (TAA) implant micromotion using model-based radiostereometric analysis (MBRSA).

Purpose

Aseptic loosening of the tibial component of total knee prosthesis is a common cause of revision surgery. While micromotion at the bone-implant interface can now be accurately measured with Radiostereometric Analysis (RSA), mechanisms responsible for loosening remain poorly understood. The purpose of this study was to investigate the association between bone density in the proximal tibia and post-operative knee implant migration.

Purpose

The foam metal backed Advance BioFoam Knee Arthroplasty components utilize a porous titanium coating on the underside of the tibial baseplate, intended to promote bone in-growth and provide a more robust bone-implant interface without cement. There is also a version of the Biofoam Advance that incorporates screwed fixation that allows for augmented fixation with up to four titanium screws; however, it is not clear that this augmentation is necessary. The purpose of this study was to employ radiostereometric analysis (RSA) to compare implant migration in a randomized controlled trial of this implant design with or without screw fixation.

Purpose

To evaluate the five year Radiostereometric Analysis (RSA) results of the NexGen LPS Trabecular Metal Tibial Monoblock component (TM) and the NexGen Option Stemmed cemented component (Cemented), (Zimmer, Warsaw IN).

Purpose: To determine if MIS for primary hip replacement surgery increases the risk of long term aseptic loosening as predicted by implant micromotion measured with radiostereometric analysis (RSA).

Method: Ninety patients undergoing primary THA for osteoarthritis (exclusion criteria: post-traumatic arthritis, rheumatoid arthritis, hip dysplasia, previous hip infection) were randomized to undergo THR surgery utilizing the standard direct lateral approach (n=45; 24 male; age=58 yrs; BMI=27) or MIS via a one-incision direct lateral approach using specific instrumentation (n=45; 23 male; age=55; BMI=29). Uncemented acetabular and femoral (ProfemurZ) components were used with ceramic on ceramic bearings. The femur was marked with 9 tantalum beads placed in the greater trochanter, lesser trochanter, and femoral shaft distal to the tip of the prosthesis. Post-operative care was be standardized according to the care maps at our institution. Primary outcome measure was femoral stem MTPM (maximum total point motion) measured using Model-based RSA. Stereo supine X-rays were taken before weight bearing and 3, 6, and 12 months postoperatively. At the same time intervals Harris Hip Score, Oxford-12, WOMAC, and SF36 questionnaires were administered. Rates of infection, dislocation and revision were recorded.

Results: Eleven patients were lost to follow-up (4 due to missing post-op exams; 5 did not have enough beads placed during surgery; 2 were revised due to failure of the ceramic femoral head). There were five long neck fractures at 17–30 months postop that are reported in detail in a related abstract. There were no differences between groups for all outcome measures. Mean MTPM at 12 months was 2.5mm (SD=1.8mm) for the MIS group and 2.6mm (SD=1.2mm) for the standard group.

Conclusion: No difference between groups at one year indicates MIS for uncemented primary THR through a direct lateral approach does not appear to negatively affect stability of the femoral stem. Although promising, these results require confirmation with 2-year RSA data.

Purpose: Despite their inclusion within clinical practice, standardized radiographs may not accurately project an individual’s level of function and mobility. The purpose of this study is to examine the potential relationship between established radiographic features and lurch; a functional measure of asymmetric gait, in a group of patients who will receive total hip arthroplasty (THA).

Method: Thirty-two patients (16 females, 16 males) identified as hip replacement candidates were recruited, with a mean age of 57.0 years. Lurch was obtained using the Walkabout Portable Gait Monitor (WPGM); a wireless, triaxial accelerometry device. The independent variables were comprised of the Kellgren-Lawrence Scale, and a collection of standard radiographic features, as adopted by the American Academy of Orthopaedic Surgeons (AAOS), the National Institutes of Health (NIH), and the World Health Organization (WHO). Radiographs were blinded, and the surgeon completing the rating scale was unaware of patient’s lurch values. Age-adjusted regression analyses were used to examine the potential association between each radiographic feature and lurch.

Results: Increased amounts of lurch (i.e. functional impairment) were independently associated with higher Kellgren-Lawrence Scale scores (p=.047), increased Joint Space Narrowing in the mid-portion of the joint (zone 2; p=.004), the presence of acetabular wear (p=.045), an increased severity of subchondral femoral head cysts (p=.004), and higher surgeon-rated Visual Analog Scale scores for overall severity of joint degeneration (p=.008). Lurch was not significantly associated with the remaining 10 features which were examined. Further analyses revealed that lurch was not significantly associated with certain demographic factors, including sex, Body Mass Index, and co-morbid health conditions.

Conclusion: Although the Kellgren-Lawrence scale was associated with an objective measure of gait, our results indicate that other radiographic features may provide a more accurate prediction of gait performance among this patient population. As lurch appears to be a robust objective measure of physical impairment, which is unaffected by BMI and co-morbidities, we believe that portable triaxial accelerometers can likely be used to conveniently collect objective gait data. This functional data may be used to supplement clinical efforts to screen and prioritize appropriate hip arthroplasty patients.

Purpose: Resurfacing arthroplasty (RA) is becoming popular as an alternative to total hip arthroplasty (THA). Direct to consumer advertising reports good to excellent outcomes and patients sometimes seek RA on the assumption that it provides increased survivorship over THA. We report the 5 year survivorship of 25 RA procedures done at one institution.

Method: 25 patients were prospectively followed after receiving a Conserve Plus RA through a direct lateral approach between 2002 and 2005. There were 22 males and 3 females with an mean age at surgery of 42 years. The average length of follow-up was 40 months. Failure was defined as revision of the components or a pending revision.

Results: At a mean of 2 years follow-up, 3 patients had been revised and 2 more were scheduled for revision surgery for a failure rate of 20%. Reasons for revision included 1 neck fracture and 2 aseptically loose acetabular components. The 2 patients waiting for revision also had aseptically loose acetabular components. Patients receiving or requiring revision were operated on throughout the series and were not necessarily part of the surgical learning curve.

Conclusion: RA of the hip done through a direct lateral approach in this series had an unacceptably high failure rate for aseptic loosening of the acetabular component.

Purpose: To meet the increasing demand for arthroplasty in Canada healthcare providers are investigating efficiency improvements to maximize utilization of limited surgical resources. One target is routine annual arthroplasty follow-up for which there are no established guidelines. A previous study by the authors revealed that 52% of arthroplasty patients could be followed with standardized questionnaires and x-rays resulting in a 30% savings to the healthcare system. In this study we report the patient time, travel and financial burdens for annual follow-up at a tertiary care centre versus a hypothetical model using standardized assessment at community hospitals and a web-enabled PACS.

Method: A consecutive sample survey of elective THA and TKA patients (n=158; 99 females; 94 THA; 64 TKA; mean age=69 years) who were at least twelve months postoperative. Patient’s address, work status, mode of travel and times required for travel, physician consult, x-ray, and clinic wait were recorded. A web-based mapping application was used to determine distances from patients’ homes to the tertiary care centre and nearest community hospital. Financial burden was calculated using Statistics Canada figures for average Canadian wage and private vehicle travel costs.

Results: Sixteen patients were working at the time of the study and 149 travelled in a private vehicle. For the tertiary care centre: round-trip distance was 168 km, total time burden was 194 minutes (travel=129 minutes, clinic wait=54 minutes, time with physician=6 minutes, x-ray=5 minutes), and total financial burden per patient was $58. For the community hospital: round-trip distance was 19 km, total time burden was 39 minutes (travel=14 minutes, clinic wait=20 minutes, x-ray=5 minutes), and total financial burden was $7.

Conclusion: Utilizing community hospital resources for arthroplasty follow-up could reduce patients’ travel by 89%, financial burden by 88%, and time burden by 81%. This approach has the potential to enable the focusing of arthroplasty clinic follow-up resources only on patients reporting problems or with symptomatic x-rays thus freeing up surgeon time for surgeries. There are also the broader societal implications of reducing ‘health miles’ and the resulting carbon dioxide emissions related to health care delivery by leveraging new technologies to move information rather than people.

Purpose: Porous metal technology may have significant impacts on implant fixation and long-term survival due to their high co-efficient of friction and similarity to trabecular bone in morphology and mechanical behaviour. While promising, the in vivo mechanical behaviour and micromotion at the interface has not previously been reported on. We report on the 2-year results of an RCT using radiosterometric analysis (RSA) to asses a porous metal (PM) monoblock tibial component.

Method: Patients undergoing TKA were randomized to receive a either the PM (n=34) or the cemented tibial component (n=33). A standardized protocol was used for intra and post-operative factors. RSA exams were obtained postoperatively within 4 days of surgery and at 6, 12 and 24 months. One patient was excluded due to an intraoperative complication, and four others were lost to follow-up due to poor bead visibility or morbidity. Standard subjective outcome measures were applied.

Results: There were no revisions in either group. The PM group exhibited two distinct migration patterns. One group stabilized immediately with similar migration to the cemented cases (0.38 vs. 0.46 p=0.4). A subset of 6 PM cases demonstrated significantly higher initial migration (mean=2.01mm, p< 0.01) but appeared stable at 2 years. In addition, 3 of the 6 high migration cases manifested independent bead subsidence. This was determined to be due to PM plate deformation. Two cemented cases were considered at risk for early failure due to aseptic loosening because of RSA migration pattern. There were no differences between groups in the subjective health outcome measures.

Conclusion: A subset of PM components demonstrated high early migration followed by stabilization. It appears that some of these PM components deformed under load, most often in the posteromedial corner, perhaps as a result of malalignment or ligament imbalance. The implications of this finding are yet to be determined.

Purpose: To investigate the effect that gender may have on the RSA defined migration pattern of cemented and uncemented tibial components in total knee arthroplasty (TKA).

Method: 70 patients with primary osteoarthritis of the knee were randomized to receive a Nexgen uncemented Trabecular Metal (TM) monoblock tibial component (n=37; 20 female; mean age=66 years; mean BMI=32) or cemented cobalt chrome modular tibial cmponent (n=33; 19 female; mean age=65 years; mean BMI=33). The same design of posterior stabilized tibial component was used in all cases. Four experienced knee surgeons followed a standardized surgical technique (PCL resection, patella resurfacing, RSA bead placement in poly-ethylene and tibia) and post-operative protocol (CPM as tolerated, no drains, WBAT). Within 4 days of surgery and at 6, 12 and 24 months post-operatively patients underwent bi-planar x-rays. RSA analysis was performed with MB-RSA (MEDIS, Leiden). Results were reported as maximum total point motion, and 6 degrees of freedom translations and rotations. A repeated measure ANOVA was used to test for differences and all statistical analysis was performed using Minitab V.14 (Minitab Inc, State College, PA, USA).

Results: Highly significant differences were seen in the migration patterns in females between the TM and cemented tibial components. Females with the TM implant tended to rotate internally (0.29° vs. −0.16°, p< 0.0001), tilt posteriorly (−0.49° vs. 0.01°, p< 0.0001) and subside (−0.357mm vs. 0.00mm, p< 0.0001) compared with the female subjects with the cemented implant. In the male group, only subsidence was different between the TM and cemented groups (−0.344mm vs. −0.01mm, p< 0.0001).

Conclusion: Uncemented TM implants in females tended to tilt posteriorly, rotate internally and subside. Uncemented implants in males tended only to subside. The increased tilting and rotation detected in females could be due to lower BMD or to mismatching between the shape of the female proximal tibial and the tibial component. These results may have implications for the current use of uncemented implants in females and for future design of uncemented implants for the female population.

The purpose of this study was to assess the effect of total knee arthroplasty (TKA) on the gait symmetry of patients suffering from osteoarthritis. TKA is an effective method of relieving pain and restoring function but many established outcome measures are subjective and based on patient self-report. This study used clinical gait analysis with the Walkabout Portable Gait MonitorTM (WPGM) to describe pre and post-operative function in a more objective manner.

The WPGM is a tri-axial arrangement of accelerometers that a subject wears around the waist, approximating the position of the center of mass (COM). Twenty-one TKA patients underwent a standardised WPGM assessment (a walk at a self-selected speed along a 50m hospital corridor) and completed the WOMAC and SF-36 subjective questionnaires preoperatively and three years after surgery. Data was recorded at 200 Hz for approximately twenty to twenty-five seconds. Automated Fast Fourier transformations (FFT) of the displacement data in three axes yields data on the ‘repeating irregularities’ that result from musculoskeletal injury or compensatory mechanisms and provides three clinically significant ratios Surge (asymmetry in the gait cycle in the forward direction), Lurch (side to side displacements that becomes asymmetrical with unilateral pathology) and Functional Leg Length Difference (FLLD) (asymmetry in vertical displacement during the gait cycle).

Paired t-tests show that mean Surge (p< 0.006), FLLD (p< 0.0001) and Lurch (p< 0.008) were reduced following TKA for treatment of osteoarthritis. This is evidence that the asymmetry of gait was successfully reduced and subsequently overall gait was improved following surgical intervention. Patients’ WOMAC and SF-36 questionnaires showed significant improvements in patient pain, stiffness and physical function post-operatively (p’s< 0.01).

Advantages of using the WPGM in addition to standard patient self-report questionnaires include the ease of testing, quick analysis and ability to detect musculo-skeletal health changes that might otherwise be masked by extraneous variables. A small subset of patients did not realise significant improvement in gait parameters post-operatively. On closer inspection, these patients had near normal gait patterns pre-operatively. This suggests the WPGM has great potential for objectively prioritizing patients waiting for TKA and assessing post-operative outcome.

The purpose of this study is to assess the clinical outcome and gait analysis of a new technique for ankle arthrodesis using a Fibular Sparing Z Osteotomy (FSZO).

The FSZO technique for ankle arthrodesis utilises a lateral approach where the fibula is osteotomised and reflected posteriorly on a soft tissue hinge to allow easy access to the ankle joint for an anatomic arthrodesis. Outcome assessment at six months follow up included health related quality of life (SF36) and joint specific (American Orthopedic Foot and Ankle Society Ankle-Hindfoot, Ankle Osteoarthritis Scale, Foot Function Index) clinical outcome scores. Gait Analysis was completed using the Walkabout Portable Gait Monitor® which includes a wireless gait belt housing a triaxial arrangement of accelerometers, resting behind the lumbar vertebrae, approximately at position of centre of mass to quatintfy surgery, lurch and functional limb length difference (LLD).

There was a significant improvement in the health related quality of life and the joint specific clinical outcome scores at six months follow up. The six month gait study preliminary analysis showed improvement in some parameters of gait but worsening in others.

The FSZO ankle arthrodesis technique provides improvement in clinical outcome scores and certain gait parameters at early follow up.

A retrospective chart review of three hundred and eighty-seven PFC© and PFC Sigma© total knee replacements performed by a single surgeon over a seven-year period was completed. During that time, there were fourteen revisions for polyethylene failure. Survival analysis indicates a failure rate of 8%. Previous reports in the literature of the survivorship of the original PFC design demonstrated a five percent failure rate over a ten-year period. Gamma sterilization in air of the PFC polyethylene and the locking mechanism of the articular surface have been implicated in premature wear and failure of this prosthesis.

The purpose of this study was to determine the revision rate due to polyethylene failure for a cohort of PFC© and PFC Sigma© total knee prostheses implanted by a single surgeon.

The early to mid-term revision rate (8%) of the PFC© and PFC Sigma© polyethylene component appears to be abnormally high. The early failure of this tibial articulating component may be related to faulty polyethylene inserts and/or failure of the locking mechanism. Attention to preparation of the polyethylene and locking mechanism of the tibial insert may need to be addressed.

Three hundred and eighty-seven total knees were performed in a cohort of three hundred and twenty-two patients (64% female; mean age = 70 ± 9 years; mean BMI = 31 ± 6). Mean follow-up was forty-one months (± 23). The revision rate at seven years was 8%. At time of revision most prostheses were solidly fixed with no overt signs of loosening of the tibial component. However, there was movement of the polyethylene in the tibial tray in both the mediolateral and AP direction with obvious surface and backside wear. Marked synovitis with evidence of osteolysis, particularly on the femoral side, was also noted. Bone graft was required in almost all cases.

A retrospective chart review was conducted for PFC© and PFC Sigma© total knee systems implanted by a single surgeon between 1995 and 2002. Collected data included patient demographics, age, gender, body mass index, and reason for surgery. The amount of synovitis and osteolysis was documented during revision surgery.

During the routine follow-up of this cohort, patients were identified with marked synovitis and increasing pain in the knee even though there was no gross mal-alignment of the tibial or femoral component.

Data from the wait list management system and hospital databases was used to develop a computer model simulating the resource requirements required during patient flow into, through, and out of orthopaedic surgery for TKR, THR and knee arthroscopy. Results from the simulation model suggested that inpatient beds, rather than operating room time was the constraining resource and an extra twenty-five beds and 30% more OR time would stabilize and subsequently reduce the wait time at the institution. In addition, simulations suggested that pooling surgeon wait lists reduced patient wait time. Simulation models are an effective resource allocation decision-making tool for orthopaedic surgery.

To develop and implement a wait list simulation model to analyze the existing system and guide resource allocation decision-making at the QEII Health Sciences Centre.

The simulation model suggests an immediate increase in inpatient surgical beds from sixty-six to ninety-one followed by a 30% increase in OR time in thirty months to stabilize and subsequently reduce patient wait times.

Simulations showed that pooling surgeon waiting lists reduced patient wait time, however, dividing orthopaedics resources among two facilities had little effect. Adding twenty-five beds reduced the wait time growth rate substantially, but not to zero, while adding fifty beds reduced the wait time growth rate to zero. Adding twenty-five beds and 30% more OR time had the same result as adding fifty beds.

Simulation models can be effective for guiding resource allocation decisions for orthopaedic surgery. Recommendations based on the wait list simulation model results were immediately adopted by the provincial Department of Health.

A simulation model of the orthopaedic surgery system at the institution was created using Arena simulation software. Empirical statistical distributions were developed based on Wait List Management System and administrative data to assign values to model variables: number of patient referrals seen per office session; proportion of patient referrals actually converting to a surgery booking; type of procedure required; admission status; time required for surgery; and length of stay. The model was tested, and validated. Several scenarios with adjusted levels of resources variables (OR time, number of surgeons, length of stay, inpatient bed availability) were simulated.

Purpose: The Advance Medial Pivot (MP) knee has higher congruency and postulated different kinematics than traditional posterior stabilized knee implants. This could lead to increased micromotion at the tibial component/bone interface potentially resulting in premature loosening. To investigate the stability of the MP knee we used maximum total point motion (MTPM) as determined with RSA to compare micromotion at the tibial component/bone interface between the Advance MP and PS knees.

Methods: A power calculation determined that a minimum sample size of 40 (20/group) was required. Sixty-six patients (48 females) with primary osteoarthritis of the knee were randomized to receive the Advance MP (n=36) or PS (n=30) knee. Three experienced knee surgeons followed a standardized surgical technique (PCL resection, patella resurfacing, RSA bead placement in polyethylene and tibia) and post-operative protocol (CPM as tolerated, no drains, WBAT). SF-36, WOMAC, PCS, KSCRS were administered to all patients pre-operatively and at 6, 12 and 24 months post-operatively and BMI was recorded. Within 4 days of surgery and at 6, 12 and 24 months post-operatively patients underwent bi-planar x-rays.

Results: Fifteen patients were lost to follow-up (2 infections, 1 death, 2 dropped out, 10 lost due to technical issues). There was no difference in MTPM between groups at 2 years. Physical function was better (p< 0.03) for the PS group at 6 months but there was no difference at 1 year.

Conclusions: There was no difference in MTPM between groups at 2 years post-op. The Advance PS knee appears to result in earlier post-operative improvements in physical function. The altered kinematics and increased congruency of the Advance MP knee does not seem to alter the forces at the tibial component/bone interface and therefore does not appear to be more prone to migration and premature aseptic loosening.

Funding : Other Education Grant

Funding Parties : Unrestricted grant from Wright Medical Inc.

Purpose: The Less Invasive Stabilization System (LISS), Dynamic Condylar Screw (DCS) and Condylar Buttress Plate (CBP) are three common fixation methods for supracondylar femur fractures. The DCS and CBP are compression plates while the LISS uses locking screws to transfer load from bone to plate without compression. We developed a study to determine if the theoretical biomechanical advantages of the LISS would be evident in laboratory testing.

Methods: Identical AO type C fractures were created in eighteen composite femurs and fixed with either LISS, CBP, or DCS (6 each). Roentgen Stereophotogrammetric Analysis (RSA) was used for analysis. Reference markers were implanted into each bone segment. Biplanar x-rays were taken to give a three-dimensional representation of the fracture. The femurs were loaded axially in an Instron 1350 and subjected to cyclic loading (50kg ± 25 for 50000 cycles). After loading, the bones were x-rayed to determine relative motion between fracture segments. To examine inducible displacement under static loading, the femurs were x-rayed in an unloaded and loaded (50 kg) condition. Again, RSA was used for analysis.

Results: RSA-CMS software was used to analyze relative motion between the bone segments. After cyclic loading, the condylar buttress plate showed significantly more permanent deformation between the medial condyle and shaft of the femur than the DCS or LISS. Under static load, the LISS showed greater displacement than the other devices between the medial condyle and shaft, and between the lateral condyle and shaft.

Conclusions: The LISS demonstrated less permanent deformation but greater inducible deformation between the medial femoral condyle and femoral shaft, compared to the DCS and CBP. The results were statistically significant. These results may have clinical implications regarding the choice of fixation devices for this difficult fracture pattern.

Funding : Other Education Grant

Funding Parties : Capital Health Research Grant

A centralized wait list management system (WLMS) for TKR, THR and knee arthroscopy was developed to collect accurate data on parameters of patients’ wait for surgery. A priority metric rating patient priority was implemented. Data from hospital enterprise systems related to aspects of patients’ wait for surgery was collected and imported. Patients’ functional status was significantly worse than population norms, they were adversely affected while waiting and are unsatisfied with their access to surgery. Traffic ratios (ratio of booked to completed surgeries) exceed the maximum value for a stable wait list and the waits for surgery exceed national and international recommendations for maximum wait-times.

To develop and implement a WLMS for TKR, THR and knee arthroscopy to enable the accurate and efficient collection of data on size of list, rate of list growth, rate surgeries are performed, health and functional status of patients, and surgeon rated priority.

Patients are adversely affected while waiting and are unsatisfied with the length of their wait. Traffic ratios exceed the maximum value for a stable waitlist. The priority metric has face validity for rating patient acuity.

SF36 and WOMAC scores were three to four standard deviations worse than the population norm, over 50% of patients felt wait time would negatively affect outcome, 80% felt waits should be twelve months or less, and over 50% were unsatisfied with access to surgery. VAS scores were normally distributed with good face validity. Wait times are one hundred and thirty to three hundred days for arthroplasty and ninety to four hundred days for arthroscopy. Traffic ratios are 0.9 for arthroplasty and 1.5 for arthroscopy.

Prospective outcomes with respect to the wait list will allow determination of minimum acceptable wait times from administrative, surgeon and patient perspectives. Accurate and reliable collection of wait list data provides a sound basis for future decision-making.

Surgery bookings were centralized. A priority metric based on a visual analog scale (VAS) with a single question asking the surgeon to rate the patient priority was implemented. A cross-sectional postal survey was conducted. Data from hospital enterprise systems related to aspects of patients’ wait for surgery was collected and imported into the WLMS.

A centralized wait list management system (WLMS) for TKR, THR and knee arthroscopy was developed to collect accurate data on parameters of patients’ wait for surgery. A priority metric rating patient priority was implemented. Data from hospital enterprise systems related to aspects of patients’ wait for surgery was collected and imported. Patients’ functional status was significantly worse than population norms, they were adversely affected while waiting and are unsatisfied with their access to surgery. Traffic ratios (ratio of booked to completed surgeries) exceed the maximum value for a stable wait list and the waits for surgery exceed national and international recommendations for maximum wait-times.

To develop and implement a WLMS for TKR, THR and knee arthroscopy to enable the accurate and efficient collection of data on size of list, rate of list growth, rate surgeries are performed, health and functional status of patients, and surgeon rated priority.

Patients are adversely affected while waiting and are unsatisfied with the length of their wait. Traffic ratios exceed the maximum value for a stable waitlist. The priority metric has face validity for rating patient acuity.

SF36 and WOMAC scores were three to four standard deviations worse than the population norm, over 50% of patients felt wait time would negatively affect outcome, 80% felt waits should be twelve months or less, and over 50% were unsatisfied with access to surgery. VAS scores were normally distributed with good face validity. Wait times are one hundred and thirty to three hundred days for arthroplasty and ninety to four hundred days for arthroscopy. Traffic ratios are 0.9 for arthroplasty and 1.5 for arthroscopy.

Prospective outcomes with respect to the wait list will allow determination of minimum acceptable wait times from administrative, surgeon and patient perspectives. Accurate and reliable collection of wait list data provides a sound basis for future decision-making.

Surgery bookings were centralized. A priority metric based on a visual analog scale (VAS) with a single question asking the surgeon to rate the patient priority was implemented. A cross-sectional postal survey was conducted. Data from hospital enterprise systems related to aspects of patients’ wait for surgery was collected and imported into the WLMS.