Timothy R. Daniels

Intermediate-Term Results of Total Ankle Replacement and Ankle Arthrodesis

BACKGROUND Surgical treatments for end-stage ankle arthritis include total ankle replacement and ankle arthrodesis. Although arthrodesis is a reliable procedure, ankle replacement is often preferred by patients. This prospective study evaluated intermediate-term outcomes of ankle replacement and arthrodesis in a large cohort at multiple centers, with variability in ankle arthritis type, prosthesis type, surgeon, and surgical technique. We hypothesized that patient-reported clinical outcomes would be similar for both procedures. METHODS Patients in the Canadian Orthopaedic Foot and Ankle Society (COFAS) Prospective Ankle Reconstruction Database were treated with total ankle replacement (involving Agility, STAR, Mobility, or HINTEGRA prostheses) or ankle arthrodesis by six subspecialty-trained orthopaedic surgeons at four centers between 2001 and 2007. Data collection included demographics, comorbidities, and the Ankle Osteoarthritis Scale (AOS) and Short Form-36 (SF-36) scores. The preoperative and latest follow-up scores for patients with at least four years of follow-up were analyzed. Sensitivity analyses excluded ankles that had undergone revision. A linear mixed-effects regression model compared scores between the groups, adjusting for age, sex, side, smoking status, body mass index, inflammatory arthritis diagnosis, baseline score, and surgeon. RESULTS Of the 388 ankles (281 in the ankle replacement group and 107 in the arthrodesis group), 321 (83%; 232 ankle replacements and eighty-nine arthrodeses) were reviewed at a mean follow-up of 5.5 ± 1.2 years. Patients treated with arthrodesis were younger, more likely to be diabetic, less likely to have inflammatory arthritis, and more likely to be smokers. Seven (7%) of the arthrodeses and forty-eight (17%) of the ankle replacements underwent revision. The major complications rate was 7% for arthrodesis and 19% for ankle replacement. The AOS total, pain, and disability scores and SF-36 physical component summary score improved between the preoperative and final follow-up time points in both groups. The mean AOS total score improved from 53.4 points preoperatively to 33.6 points at the time of follow-up in the arthrodesis group and from 51.9 to 26.4 points in the ankle replacement group. Differences in AOS and SF-36 scores between the arthrodesis and ankle replacement groups at follow-up were minimal after adjustment for baseline characteristics and surgeon. CONCLUSIONS Intermediate-term clinical outcomes of total ankle replacement and ankle arthrodesis were comparable in a diverse cohort in which treatment was tailored to patient presentation; rates of reoperation and major complications were higher after ankle replacement.

AOFAS Position Statement Regarding the Future of the AOFAS Clinical Rating Systems

Validated outcome measures are useful tools in orthopaedic clinical practice and research for evaluating the effect of a treatment intervention on patient status. There are a wide range of measures used in the evaluation of foot and ankle surgery and attempts to consolidate and standardize them are under way. Unfortunately, not all outcome measures have shown measurement properties that meet recommended quality criteria.13 This makes choosing an appropriate outcome measure all the more difficult and, at this point in time, puts the onus on the researcher to carefully review the evidence for a particular measure. Despite the limited evidence supporting the validity of the American Orthopaedic Foot and Ankle Society (AOFAS) Clinical Rating Systems7 and the interpretation of their scores, they continue to be among the most commonly used measures selected by researchers.1,2,4,6,9,11,13,17 Based on the basic algorithm used by the earliest orthopaedic outcome measures, the Iowa Hip Score8 and its successor the Harris Hip Score,5 the framework for the AOFAS Clinical Rating Systems combines physical examination criteria with self-reported pain and function items.11 When a clinical examination is part of a scoring system, this introduces a high risk of inter-observer variability as different examiners may have different measuring techniques.14 This can affect the reliability of a score, i.e., its measurement consistency. Intra-observer and inter-observer relations have not yet been evaluated for the AOFAS Clinical

Intermediate Outcomes of Fresh Talar Osteochondral Allografts for Treatment of Large Osteochondral Lesions of the Talus

BACKGROUND Large osteochondral defects of the talus present a treatment challenge. Fresh osteochondral allograft transplantation can be used for large lesions without the donor-site morbidity associated with other procedures such as autologous chondrocyte implantation or osteochondral autograft transfer. The goal of this study was to prospectively evaluate the intermediate outcomes of fresh osteochondral allografting for osteochondral lesions of the talus with use of validated outcome measures. METHODS Sixteen patients (seventeen ankles) received a fresh osteochondral allograft, and all sixteen were available for follow-up. Data were prospectively collected with use of the Ankle Osteoarthritis Scale (AOS), Short Form-36 (SF-36), and American Academy of Orthopaedic Surgeons (AAOS) Foot and Ankle Module outcome measures. Postoperative American Orthopaedic Foot & Ankle Society (AOFAS) hindfoot scale scores were also collected. All sixteen patients underwent radiographic and computed tomographic (CT) analyses preoperatively, and fifteen patients had these studies postoperatively. RESULTS The average duration of follow-up was 4.1 years. The latest follow-up CT evaluation identified failure of graft incorporation in two of sixteen ankles. Osteolysis, subchondral cysts, and degenerative changes were found in five, eight, and seven ankles, respectively. Five ankles were considered failures, and two required a reoperation because of ongoing symptoms. The AOS Disability and the AAOS Foot and Ankle Core Scale scores significantly improved, but there was no significant change in the AOS Pain, AAOS Foot and Ankle Shoe Comfort Scale, or SF-36 scores. Overall, ten patients had a good or excellent result; however, persistent symptoms remained in six of these patients. Only four were symptom-free. CONCLUSION The use of a fresh osteochondral allograft is a reasonable option for the treatment of large talar osteochondral lesions. The high reoperation rate (two of seventeen) and failure rate (five of seventeen) must be taken into consideration when one is choosing this procedure for the management of these lesions.

Weightbearing CT Scan of Severe Flexible Pes Planus Deformities

Background: The three-dimensional relationships of the bones in the foot in a flatfoot deformity are difficult to assess with standard radiographs. CT scans demonstrate these relationships but are typically made in a nonweightbearing mode. Our objective was to assess the use of a weightbearing CT apparatus to image the feet in patients with severe flexible pes planus deformities and to better define the anatomical changes that occur. Materials and Methods: A specialized device was designed and constructed to simulate weightbearing to the feet during CT examination. Eighteen normal feet and 30 painful severe and flexible pes planus feet were imaged in both the non weightbearing and weightbearing states, set at 50% of body weight. Several measurements of intertarsal relationships were made of the pes planus and normal feet. Navicular floor to skin distance, forefoot arch angle, and subtalar joint subluxation were measured in the coronal plane in both the weightbearing and nonweightbearing states. T-tests were used to analyze measurements of navicular floor to skin distance and forefoot arch angle. Results: The weightbearing device had a significant effect on foot configuration for both normal and pes planus feet (p = 0.0008) and (p < 0.0001) respectively for both floor to skin distance and forefoot arch angle. There was a significant difference between normal feet and pes planus feet with regard to the forefoot arch angle in the nonweightbearing (p = 0.02) and weightbearing states (p = 0.01). Four of the pes planus patients had evidence of subtalar joint subluxation which was more pronounced in the weightbearing state. There was no significant difference between the navicular floor to skin distance in the normal versus pes planus feet in either the non weightbearing (p = 0.05) or the weightbearing states (p = 0.07). Conclusion: A device was designed and constructed to apply a weightbearing load equal to that of 50% body weight with minimal to no patient discomfort. The resultant effects on foot configuration were significant, and are useful for assessment of degree of flexible flat foot deformity, thus guiding clinical management. The measure which most significantly differed between pes planus patients and normal volunteers was the forefoot arch angle. Forefoot arch angle may therefore be the most useful measure for the imaging diagnosis of flexible pes planus, and the degree of planus deformity.

Recombinant Human Platelet-Derived Growth Factor-BB and Beta-Tricalcium Phosphate (rhPDGF-BB/β-TCP): An Alternative to Autogenous Bone Graft

BACKGROUND Joint arthrodesis employing autogenous bone graft (autograft) remains a mainstay in the treatment of many foot and ankle problems. However, graft harvest can lead to perioperative morbidity and increased cost. We tested the hypothesis that purified recombinant human platelet-derived growth factor-BB (rhPDGF-BB) homodimer combined with an osteoconductive matrix (beta-tricalcium phosphate [β-TCP]) would be a safe and effective alternative to autograft. METHODS A total of 434 patients were enrolled in thirty-seven clinical sites across North America in a prospective, randomized (2:1), controlled, non-inferiority clinical trial to compare the safety and efficacy of the combination rhPDGF-BB and β-TCP with those of autograft in patients requiring hindfoot or ankle arthrodesis. Radiographic, clinical, functional, and quality-of-life end points were assessed through fifty-two weeks postoperatively. RESULTS Two hundred and sixty patients (394 joints) underwent arthrodesis with use of rhPDGF-BB/β-TCP. One hundred and thirty-seven patients (203 joints) underwent arthrodesis with use of autograft. With regard to the primary end point, 159 patients (61.2% [262 joints (66.5%)]) in the rhPDGF-BB/β-TCP group and eighty-five patients (62.0% [127 joints (62.6%)]) in the autograft group were fused as determined by computed tomography at six months (p < 0.05). Clinically, 224 patients (86.2%) [348 joints (88.3%)]) in the rhPDGF-BB/β-TCP group were considered healed at fifty-two weeks, compared with 120 patients (87.6% [177 joints (87.2%)] in the autograft group (p = 0.008). Overall, fourteen of sixteen secondary end points at twenty-four weeks and fifteen of sixteen secondary end points at fifty-two weeks demonstrated statistical non-inferiority between the groups, and patients in the rhPDGF-BB/β-TCP group were found to have less pain and an improved safety profile. CONCLUSIONS In patients requiring hindfoot or ankle arthrodesis, treatment with rhPDGF-BB/β-TCP resulted in comparable fusion rates, less pain, and fewer side effects as compared with treatment with autograft.

Prospective Clinical Pilot Trial in a Single Cohort Group of rhPDGF in Foot Arthrodeses

Background: Augment™ Bone Graft, a fully synthetic bone graft material composed of recombinant human PDGF and a calcium phosphate matrix (rhPDGF/TCP), has been considered as a possible alternative to autogenous bone graft. Before proceeding with randomized control studies comparing rhPDGF/TCP to autograft bone, a human trial to assess efficacy and safety was required. Materials and Methods: The current study was a prospective, open-label, multi-center trial designed to evaluate rhPDGF in a calcium phosphate matrix (Augment™ Bone Graft). Sixty patients requiring hindfoot or midfoot fusion were prospectively followed for 36 weeks. All patients received 0.9 to 2.7 mg of rhPDGF at the fusion sites and returned for clinical and radiographic review at Day 7 to 14 and Weeks 6, 9, 12, 16, 24, and 36. Computerized tomography (CT) scans of the fusion site were obtained at the 6- and 12-week postoperative appointment, with an additional CT scan at 16 weeks if required. Results: No patients suffered a serious adverse event caused by rhPDGF. CT scan evaluation at 12- to 16-week time periods revealed moderate or complete osseous bridging of 75% (44/59) at 36 weeks. Conclusion: These results indicate that rhPDGF is a safe product and provides clinical/radiographic outcomes that justify the pursuit of randomized controlled studies comparing rhPDGF/TCP to autograft. Level of Evidence: IV, Case Series

The Orthopaedic Foot and Ankle Outcomes Research (OFAR) network: feasibility of a multicenter network for patient outcomes assessment in foot and ankle.

Introduction: There is an increasing need for orthopaedic practitioners to measure and collect patient-reported outcomes data. In an effort to better understand outcomes from operative treatment, the American Orthopaedic Foot & Ankle Society (AOFAS) established the Orthopaedic Foot and Ankle Outcomes Research (OFAR) Network, a national consortium of foot and ankle orthopaedic surgeons. We hypothesized that the OFAR Network could successfully collect, aggregate, and report patient-reported outcome (PRO) data using the National Institutes of Health (NIH) Patient Reported Outcomes Measurement Information System (PROMIS). Methods: Ten sites enrolled consecutive patients undergoing elective surgery for 1 of 6 foot/ankle disorders. Outcome instruments were collected preoperatively and at 6 months postoperatively using the PROMIS online system: Foot and Ankle Ability Measure (FAAM), Foot Function Index (FFI), and PROMIS physical function (PF) and pain computerized adaptive tests (CAT). During the 3-month period, 328 patients were enrolled; 249 (76%) had completed preoperative patient-reported outcomes data and procedure-specific data. Of these, 140 (56%) also completed 6-month postoperative patient- reported outcomes data. Results: Ankle arthritis and flatfoot demonstrated consistently worse preoperative scores. Five of 6 disorders showed significant improvement at 6 months on PF CAT and FAAM, 4 of 6 showed improvement on pain interference CAT, and no disorders showed improvement on FFI. Ankle arthritis and flatfoot demonstrated the greatest magnitude of change on most patient-reported outcomes scales. Conclusion: We were able to enroll large numbers of patients in a short enrollment period for this preliminary study. Data were easily aggregated and analyzed. Substantial loss of follow-up data indicates a critical area requiring further effort. The AOFAS OFAR Network is undergoing expansion with goals to ultimately facilitate large, prospective multicenter studies and optimize the quality and interpretation of available outcome instruments for the foot and ankle population. Level of Evidence: Level II, prospective comparative study.

Establishing the Relationship Between Clinical Outcome and Extent of Osseous Bridging Between Computed Tomography Assessment in Isolated Hindfoot and Ankle Fusions

Background: Determining the success of joint fusion operations is often a diagnostic dilemma, and many factors may be considered. Most would agree that the broad categories of clinical success and radiographic success are likely most useful to determine the overall success of a joint fusion operation. Very little evidence exists to assist the surgeon in determining what constitutes a successful radiographic fusion. The aim of this study was to determine the extent of osseous bridging as measured by computed tomography (CT) that was associated with a good clinical outcome as measured by the 12-Item Short Form (SF-12), Foot Function Index (FFI), and American Orthopaedic Foot & Ankle Society (AOFAS) clinical outcomes questionnaires at 24 weeks. Methods: Patients who had isolated joint fusions were evaluated (n = 275) to determine the correlation of extent of osseous bridging with clinical outcome. The extent of osseous bridging across the joint in question was categorized as absent (0%-24%), minimal (25%-49%) moderate (50%-74%), or complete (75%-100%). Clinical outcome scores included the SF-12, FFI, and AOFAS outcomes score. Results: Patients evaluated to have at least minimal osseous bridging at fusion sites (25%-49%) on CT reported a clinically important improvement in SF-12, FFI, and AOFAS, whereas those with “absent” osseous bridging (0%-24%) did not report a clinically important improvement in outcome scores. Conclusion: This study suggests that osseous bridging of greater than 25% to 49% at the fusion site measured by CT may be necessary to consider a hindfoot or ankle fusion clinically successful. Level of Evidence: Level IV, case series.

Inter- and Intraobserver Reliability of the COFAS End-Stage Ankle Arthritis Classification System

Background: End-stage ankle arthritis should have an appropriate classification to assist surgeons in the management of end-stage ankle arthritis. Outcomes research also requires a classification system to stratify patients appropriately. Materials and Methods: Six fellowship trained foot and ankle surgeons met on two occasions to derive a classification system for end-stage ankle arthritis. A four-part classification system was designed. Four surgeons reviewed blinded patient profiles and radiographs on two occasions to determine the inter- and intraobserver reliability. Results: Good interobserver reliability (kappa = 0.62) and intraobserver reproducibility (kappa = 0.72) was demonstrated for the classification system. Conclusion: The COFAS classification system appears to be a valid tool for the management and research of end-stage ankle arthritis.

Reliability and validity of 6 measures of pain, function, and disability for ankle arthroplasty and arthrodesis.

Background: Patient-reported outcome measures are increasingly used evaluating clinical care. Many measures used to assess operative hindfoot interventions vary in content, and some have not been psychometrically validated in this population. The purpose of this study was to compare measurement properties of 6 lower-extremity patient-reported outcome measures, and to evaluate their reliability and validity in light of patients’ preferences. Methods: Cross-sectional survey of 42 preoperative and 100 postoperative patients completed 6 lower-extremity outcome measures on 2 occasions: Foot Function Index (FFI), Ankle Osteoarthritis Scale (AOS), patient-reported items of the American Orthopaedic Foot & Ankle Society Questionnaire (AOFAS), Lower Extremity Functional Scale (LEFS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and the Short Musculoskeletal Function Assessment (SMFA), as well as measures of preference, and symptoms. Results: Internal consistency was good to excellent for all scales and subscales (α = .84-.97; ICC [2,1] = .81-.96). Correlations between scales ranged from .50 (WOMACStiffness and FFIActivity Limitations) to .92 (LEFS and SMFAOverall, WOMACPain and AOSOverall, FFIOverall and AOFASOverall). Higher correlations occurred within instruments (r = .97 AOSPain and AOSOverall) and between similar subscales from different instruments (r = .91 WOMACPain and AOSPain). Construct validity showed moderate to high correlations to global ratings of Pain, Stiffness, and difficulty performing Daily Activities. The highest correlations (r > .75) occurred between Pain and AOSOverall (r = .84), stiffness and WOMACStiffness (r = .81), and Daily Activities and AOSDisability (r = .87). Patients rated instruments by preference. FFI, WOMAC, LEFS, and SMFA rated favorably for length. FFI, WOMAC, LEFS, and AOFAS rated high for understandability. FFI was rated by postoperative patients as most likely to capture change due to surgery. SMFA rated the best overall. Conclusions: Direct comparison of instruments revealed similarity between scales in construct validity and reliability. Patient preferences supported the use of these scales. Foot-specific instruments offered no clear advantage over lower-extremity instruments. Level of Evidence: Level II, prospective comparative study.