Ankle plantar flexor muscle performance and patient reported outcomes in people following total ankle arthroplasty.

BACKGROUND: The purpose of this study was to prospectively evaluate ankle power generation during gait in people with total ankle arthroplasty, and examine the relationships between postoperative plantar flexor strength, ankle power, and patient outcomes. METHODS: Nineteen people with end-stage ankle arthritis who received a total ankle arthroplasty and 19 healthy matched controls participated in this case-control study. Patient reported outcomes included a region specific measure of foot function and a generic measure of physical function. Gait speed was recorded with the 6-min walk test. Isokinetic plantar flexor strength was measured with an instrumented dynamometer. Motion capture and force plate data were used to calculate peak ankle power generation during walking. Paired or independent t-tests were used to compare ankle power across time and between groups, respectively. Bivariate correlations were performed to examine the interplay of postoperative strength, ankle power, gait speed, and patient reported outcomes. FINDINGS: Ankle power was not different between the preoperative and 6-month postoperative time points (d = 0.20). Six-month postoperative ankle power was less than controls (d = 1.32). Strength, ankle power, and gait speed were directly correlated in the patient group 6-months postoperatively (r or ρ ≥ 0.47). Six-month postoperative strength and ankle power were directly correlated to select 2-year patient reported outcomes (both ρ = 0.54). INTERPRETATION: Lower than normal 6-month postoperative ankle power, which was correlated to strength, gait speed, and longer-term patient reported outcomes, suggests efforts toward improving ankle plantar flexor muscle performance may improve patient outcomes.

Total ankle arthroplasty: Strength, pain, and motion.

BACKGROUND: While outcomes such as pain and ankle motion are well researched, information regarding the effect of total ankle arthroplasty on ankle plantarflexion strength is extraordinarily limited. The purpose of this study was to evaluate ankle plantarflexion strength before and after total ankle arthroplasty, and examine the interplay of pain, motion, and strength. METHODS: This prospective case-control study included 19 patients with end-stage ankle arthritis who received a total ankle arthroplasty and 19 healthy control participants matched for age, sex, and body mass index. Pain was measured with a numeric pain rating scale. Passive sagittal plane ankle range of motion (°) and isokinetic ankle plantarflexion torque (Nm/kg) at 60 and 120°/s were measured with an instrumented dynamometer. t-tests or non-parametric tests were used to evaluate outcomes across time and between groups. Bivariate correlations were performed to evaluate the interplay of postoperative pain, motion, and torque. FINDINGS: Patient pain and motion improved between the preoperative and six-month postoperative time points (d ≥ 0.7). Ankle plantarflexion torque was not different across time (d ≤ 0.5), but was lower than control group values postoperatively (d ≥ 1.4). Significant correlations between pain and motion (r = -0.48), but not torque (-0.11 ≤ r ≤ 0.13), were observed. INTERPRETATION: Unchanged following surgery, impairments in muscle performance following total ankle arthroplasty do not appear to be changed by improved pain or motion. These findings provide impetus for postoperative strengthening interventions.

Midfoot Function Before and After Total Ankle Arthroplasty.

BACKGROUND: Information regarding the effect of total ankle arthroplasty (TAA) on midfoot function is extremely limited. The purpose of this study was to characterize midfoot region motion and power during walking in people before and after TAA. METHODS: This was a prospective cohort study of 19 patients with end-stage ankle arthritis who received a TAA and 19 healthy control group participants. A motion capture and force plate system was used to record sagittal and transverse plane first metatarsal and lateral forefoot with respect to hindfoot motion, as well as sagittal plane midfoot region positive and negative peak power during walking. Parametric or nonparametric tests to examine differences and equivalence across time were conducted. Comparisons to examine differences between postoperative TAA group and control group foot function were also performed. RESULTS: Involved-limb midfoot function was not different between the preoperative and 6-month postoperative time point in the TAA group (all P ≥ .17). Equivalence testing revealed similarity in all midfoot function variables across time (all P < .05). Decreased first metatarsal and lateral forefoot motion, as well as positive peak power generation, were noted in the TAA group postoperative involved limb in comparison to the control group (all P ≤ .01). CONCLUSION: The similarity of midfoot function across time, along with differences in midfoot function in comparison to controls, suggests that TAA does not change midfoot deficits by 6 months postoperation. LEVEL OF EVIDENCE: Level II, prospective cohort study.

The Impact of Patient Age on Foot and Ankle Arthrodesis Supplemented with Autograft or an Autograft Alternative (rhPDGF-BB/ß-TCP).

A recent survey of orthopaedic surgeons asking about risk factors for nonunion following foot and ankle arthrodesis revealed that patient age is considered to be a relatively low risk factor, despite the potential for autologous graft quality to deteriorate with increasing age. The purpose of the current study was to evaluate the impact of patient age and graft type on fusion rates following hindfoot and ankle arthrodesis. METHODS: In this study, we analyzed data from a previously published clinical trial, comparing fusion success in 397 subjects who underwent hindfoot or ankle arthrodesis (597 joints) supplemented with either autograft or an osteoinductive autograft alternative, recombinant human platelet-derived growth factor-BB homodimer carried in beta-tricalcium phosphate (rhPDGF-BB/ß-TCP). The odds of fusion success were compared among subjects older or younger than age thresholds of 55, 60, 65, 70, and 75 years. The odds of fusion success were also compared between autograft and rhPDGF-BB/ß-TCP among subjects older than each age threshold. RESULTS: In the autograft group, the joints of subjects who were younger than the age thresholds of 60 and 65 years had >2 times the odds of successful fusion compared with those of older subjects. There was no significant difference in the odds of fusion success between the older and younger subjects at the age threshold of 55 years. In the rhPDGF-BB/ß-TCP group, there was no significant difference in the odds of successful fusion between older and younger subjects at any age threshold. When the odds of fusion success were compared between the 2 graft materials in subjects who were older than each age threshold, rhPDGF-BB/ß-TCP had approximately 2 times the odds of fusion success compared with autograft for all thresholds, except 55 years. CONCLUSIONS: The presented evidence suggests that age is an identifiable and concerning risk factor for hindfoot and ankle arthrodesis nonunion, a finding in contrast to the wider perception in the surgeon community. Notably, patients ≥60 years of age had significantly lower odds of fusion success with the use of autograft. The data reveal that use of rhPDGF-BB/ß-TCP as an alternative bone-healing adjunct may help mitigate the risk of nonunion when these procedures are performed in the elderly population. LEVEL OF EVIDENCE: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Overall Health and the Influence of Physical Therapy on Physical Function Following Total Ankle Arthroplasty.

BACKGROUND: The overall health and the importance of physical therapy for people following total ankle arthroplasty (TAA) have been understudied. Our purpose was to characterize the overall health of patients following TAA, and explore the frequency, influence, and patient-perceived value of physical therapy. METHODS: People who received a TAA participated in this retrospective cohort online survey study. The survey included medical history questions and items from the Patient-Reported Outcomes Measurement Information System (PROMIS) Short Forms. Seven PROMIS domains, reflecting the biopsychosocial model of care (physical, mental, social), were included to examine participant overall health status in comparison to the general population. Items regarding physical therapy participation (yes/no), number of visits, and perceived value (scale 0-10; 10 = extremely helpful) were also included. Descriptive statistics were generated for participant characteristics, PROMIS domain T scores, and physical therapy questions. The influence of participant characteristics or physical therapy visits on PROMIS domain T scores that scored below the population mean were examined with multiple linear regression or ordinal regression. RESULTS: The response rate was 61% (n=95). Average postoperative time was approximately 3 years (mean [SD]: 40.0 [35.3] months). Physical function and ability to participate in social roles and activities domain T scores were at least 1 SD below the population mean. Most patients received physical therapy (86%; 17.1 [11.0] visits) and found it helpful (7.2 [3.0]). Participant characteristics were minimally predictive of physical function and social participation T scores. Number of physical therapy visits predicted physical function T scores (P = .03). CONCLUSIONS: Most health domain scores approached the population mean. Physical therapy was perceived to have a high value, and greater visits were related to greater physical function. However, lower physical function and social participation scores suggest that postoperative care directed toward these domains could improve the value of TAA and promote overall health. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Two-Stage Varus Correction.

Coronal plane deformity following total ankle arthroplasty has been associated with poor clinical outcomes and early prosthesis failure. Neutral mechanical alignment and prosthetic joint stability must be achieved through meticulous surgical planning and precise technical execution. Cavovarus foot deformity and varus malalignment of the lower extremity is reviewed, with particular emphasis as it relates to total ankle arthroplasty. Correction of varus malalignment may be performed at the time of total ankle arthroplasty or as a 2-stage procedure. Surgeon experience, revision total ankle arthroplasty, and subtalar arthrodesis should be considerations when contemplating 2-stage varus correction.

Wear Characteristics of Conventional Ultrahigh-Molecular-Weight Polyethylene Versus Highly Cross-Linked Polyethylene in Total Ankle Arthroplasty.

BACKGROUND: The aim of this study was to compare the polyethylene wear rate, particle size, and particle shape of primary semiconstrained, fixed-bearing, bone-sparing total ankle arthroplasty using conventional ultrahigh-molecular-weight polyethylene (CPE) versus highly cross-linked polyethylene (HXLPE) by applying a level walking input using a joint simulator. METHODS: Two fixed-bearing total ankle replacement systems with different types of polyethylene liners were tested: (1) CPE sterilized in ethylene oxide, and (2) HXLPE sterilized with gas plasma after electron beam irradiation. Three implants for each design underwent wear testing using gravimetric analysis over 5 million simulated walking cycles. A fourth implant was used as a load soak control. Equivalent circle diameter (ECD) and equivalent shape ratio (ESR) were computed to determine particle size and particle shape, respectively. RESULTS: The mean wear rate from 1.5 to 5 million cycles (MC) was 2.0 ± 0.3 mg/MC for HXLPE and 16.7 ± 1.3 mg/MC for CPE ( P < .001). The total number of particles per cycle generated for HXLPE and CPE were 0.17 × 106 particles/cycle and 0.53 × 106 particles/cycle, respectively ( P < .001). The mean ECD of HXLPE particles (0.22 ± 0.11 µm) was significantly smaller than the mean ECD of CPE particles (0.32 ± 0.14 µm) ( P < .001). HXLPE particles were significantly more round than CPE particles ( P < .001). CONCLUSIONS: HXLPE liners had a significantly lower wear rate and produced significantly fewer and rounder particles than CPE liners. The results of this study suggest that HXLPE has more favorable wear characteristics for total ankle arthroplasty. CLINICAL RELEVANCE: Polyethylene wear particles have been linked to osteolysis after total ankle arthroplasty. There is no consensus on the importance of highly cross-linked polyethylene in total ankle arthroplasty with regard to implant wear. This is the first nonindustry study to compare the polyethylene wear rate, particle size, and particle shape of fixed-bearing total ankle arthroplasty conventional polyethylene versus highly cross-linked polyethylene. The lower wear rate and different particle size/morphology of highly cross-linked polyethylene could be beneficial in vivo to decrease osteolysis.

Histological Analysis of Early Osteolysis in Total Ankle Arthroplasty.

BACKGROUND: The purpose of this study was to perform a histological comparative analysis of tibiotalar joint samples taken from areas of osteolysis adjacent to total ankle arthroplasties vs control synovial specimens to determine the reaction to and presence of polyethylene (PE) particles. METHODS: A total of 57 pathology samples were identified in the osteolysis group, while 11 were identified in the control group. For each sample, hematoxylin and eosin, Oil Red O (ORO), and macrophage marker CD163-stained slides were created. Polarized light and ORO stain were used to identify PE particles. The presence of metal particles and giant cell reaction to PE particles were also scored. RESULTS: Macrophages, PE particles, metallosis, and foreign body giant cell reaction scores were significantly higher in the osteolysis group compared with the control group. In the osteolysis group, ORO staining was positive in 93% (53/57), birefringent material was present in 96.5% (55/57), and macrophage infiltrates were present in 96.5% (55/57). Foreign body giant cell reaction with giant cells surrounding PE particles was present in 49.1% (28/57) of osteolytic specimens. The presence of foreign body giant cell reaction was associated with significantly higher macrophage, ORO, and polarizable material scores. The average time to surgery for osteolysis from the index ankle replacement was 6.0 (range, 0-15) years for the 57 patients in the osteolysis group. CONCLUSION: This study is the largest ankle arthroplasty histological analysis to show that areas of osteolysis consist of abundant polyethylene wear particles, present both intracellularly and extracellularly. Furthermore, these areas were associated with a CD163+ macrophage infiltrate and frequently a foreign body reaction with giant cells engulfing PE particles. It is likely that implant wear particles play a significant role in osteolysis based on the histopathology. LEVEL OF EVIDENCE: Level III, retrospective comparative series.

Effect of Obesity on Total Ankle Arthroplasty Outcomes.

BACKGROUND: The purpose of this study was to evaluate the effect of obesity on intermediate- to long-term implant failure rates and survivorship after total ankle arthroplasty. METHODS: A chart review was performed for all patients who underwent primary total ankle arthroplasty between 2004 and 2009 with a minimum 5-year follow-up. Patients were separated into a reference group with a body mass index less than 30 kg/m2 and an obese group with an index greater than or equal to 30 kg/m2. Minimum 5-year follow-up outcomes were available for 49 patients in the obese group and 48 patients in the nonobese group. Mean follow-up was 8.2 ± 2.0 years (range, 5.1-11.5 years) in the reference group and 7.7 ± 2.0 years (range, 5.0-11.9 years) in the obese group (P = .26). RESULTS: Based on multivariable logistic regression, obese patients had a significantly greater probability of implant failure by final follow-up (adjusted odds ratio, 2.8 [95% CI, 1.04-7.53]; P = .04). Cox regression analysis of 5-year implant survivorship showed no significant difference between the 2 groups (adjusted hazard ratio, 1.89 [95% CI, 0.77-4.65]; P = .17). When compared with obese patients with inflammatory or posttraumatic arthritis, obese patients with osteoarthritis demonstrated a significantly decreased 5-year survivorship (adjusted hazard ratio, 3.73 [95% CI, 1.05-10.43]; P = .04). CONCLUSION: This study demonstrated an increased long-term risk of implant failure among obese patients that was not seen in the intermediate term. Furthermore, obese patients with primary osteoarthritis were found to have a significantly decreased 5-year implant survivorship after ankle arthroplasty as compared with obese patients with inflammatory or posttraumatic arthritis and therefore should be counseled appropriately when deciding between arthroplasty and arthrodesis. LEVEL OF EVIDENCE: Level III, retrospective comparative series.

Reduction in Wound Complications After Total Ankle Arthroplasty Using a Compression Wrap Protocol.

BACKGROUND: The purpose of this study was to evaluate the clinical differences in wound complications after total ankle arthroplasty (TAA) between a cohort of patients that received a compression wrap protocol and a historical control group treated with cast immobilization. METHODS: Patient charts and postoperative wound pictures were reviewed for 42 patients who underwent a compression wrap protocol and 50 patients who underwent circumferential casting after primary TAA from 2008 to 2013. A blinded reviewer graded each wound using a novel postoperative wound classification system, and recorded whether the wound was completely healed by or after 3 months. A second blinded review was performed to determine intraobserver reliability. Mean patient age was 55 years (range, 24-80) and all patients had at least 6-month follow-up. RESULTS: There were significantly more total wound complications (P = .02) and mild wound complications (P = .02) in the casted group compared to the compression wrap group. There were no significant differences in the number of moderate and severe complications between each group. A significantly higher proportion of TAA incisions took longer than 3 months to heal in the casted group (P = .02). CONCLUSIONS: Based on our clinical experience with postoperative wound care after TAA, use of a compression wrap protocol was safe and effective at reducing wound-related complications, and well tolerated by patients. Further prospective, randomized clinical trials are warranted to evaluate the utility and cost-effectiveness of a compression wrap protocol after TAA.

Evaluation and management of the painful total ankle arthroplasty.

Total ankle arthroplasty (TAA) is an increasingly popular treatment option for patients with end-stage ankle arthritis. Although improved short- and long-term clinical and radiographic outcomes have been achieved with TAA, revision surgery may be necessary in the setting of aseptic loosening, subsidence, impingement, arthrofibrosis, or infection. Factors such as patient selection, implant design, and surgical technique can all contribute to TAA failure. Treatment of patients with a painful TAA is complex and requires careful consideration of symptom history, workup, and nonsurgical and surgical treatment options. Surgical management of failed TAA includes arthrodesis, revision surgery, or below-knee amputation.

Early clinical and radiographic outcomes of intramedullary-fixation total ankle arthroplasty.

BACKGROUND: The present study evaluated the early clinical outcomes, radiographic parameters, and survivorship of first and second-generation INBONE intramedullary-fixation total ankle arthroplasties. METHODS: Fifty-nine primary total ankle arthroplasties utilizing INBONE I or II implants were performed in fifty-nine patients (thirty-one men and twenty-eight women; mean age, 57.2 years) from 2008 to 2012. The AOFAS (American Orthopaedic Foot & Ankle Society) ankle-hindfoot score and VAS (visual analog scale) pain score were recorded preoperatively and at the time of the latest follow-up. Weight-bearing radiographs were used to determine ankle motion and assess component alignment and subsidence. Intraoperative and postoperative complications, reoperations, and failures were evaluated. RESULTS: All fifty-nine patients were available for follow-up at least two years after surgery; the mean follow-up duration was 35.0 ± 11.9 months. The estimated survival rate at two years was 96.6% in the entire cohort (91.3% in the INBONE I group and 100% in the INBONE II group) when revision of the tibial and/or the talar component was used as the end point. The mean AOFAS ankle-hindfoot score improved from 44.1 to 87.3 at the time of the latest follow-up (p < 0.01), and the mean VAS pain score improved from 8.1 to 1.6 (p < 0.01). Mean total ankle motion improved from 29.0° to 38.0° (p < 0.01). Fourteen patients (24%) required a reoperation because of a postoperative complication. Five of these patients (four with INBONE I implants and one with INBONE II implants; 8% of the entire cohort) required revision surgery at a mean of 32.4 months (range, fifteen to fifty-eight months) because of symptomatic talar subsidence. Talar revisions utilized an INBONE II implant with a pegged talar sulcus for definitive management. The patients who underwent revision surgery had mean total ankle motion of 41.6°, neutral alignment, and no further reoperations at the time of the latest follow-up. CONCLUSIONS: Early results of INBONE intramedullary-fixation total ankle arthroplasty demonstrated improved patient-reported outcomes and increased ankle motion at a minimum follow-up of two years. Arthrofibrosis and talar subsidence were the main postoperative complications that required revision, and these predominantly affected the first-generation INBONE I implants.

Effects of Continuous Irrigation During Burring on Thermal Necrosis and Fusion Strength in a Rabbit Arthrodesis Model.

BACKGROUND: High-speed burring used to prepare bony surfaces during arthrodesis procedures can increase heat generation that may impede healing and fusion. Irrigation during burring has the potential to improve early healing of burred bone surfaces and result in a stronger fusion mass. The purpose of this study was to determine the effects of continuous irrigation during burring on thermal necrosis and fusion strength in an in vivo arthrodesis animal model. METHODS: A small joint rabbit ulnohumeral arthrodesis model was developed and utilized in 16 New Zealand white rabbits. Joints were prepared and contoured using a high-speed cutting burr and fixed in compression with crossed screws to obtain fusion. Prepared bony surfaces were either irrigated (n = 8) with chilled 6°C (43°F) saline or not irrigated (n = 8). Specimens were harvested, radiographed, mechanically tested for torque to failure and stiffness, and evaluated for histology. RESULTS: Fusion rate was 100% (8/8) when joints were irrigated during burring and 75% (6/8) when joints were not irrigated (P = .45). Mechanical testing showed a mean torque to failure of 0.85 Nm and 0.72 Nm in irrigated and nonirrigated specimens, respectively (P = .57). Histology showed evidence of less mature osseous formation in nonirrigated specimens compared to irrigated specimens. CONCLUSION: There was an overall trend toward decreased fusion rate and lower fusion mass strength in nonirrigated fusion specimens compared with those treated with chilled irrigation during bone preparation. CLINICAL RELEVANCE: Continuous chilled irrigation during bone preparation with burring may have a positive effect on fusion rate and fusion mass strength for arthrodesis procedures.

Effects of total ankle arthroplasty training course on physician practice patterns and complication rates.

BACKGROUND: The purpose of this retrospective survey study was to determine the short-term effects of the AAOS/AOFAS total ankle arthroplasty (TAA) training course on participant practice patterns, implant preferences, and complication rates. METHODS: An anonymous digital survey was administered via email to all 2012 and 2013 participants. Data regarding industry courses attended, implant system preferences, surgical indications, case volume, patient age, complication rates, and overall perceptions of TAA in the three months before and after the course were collected and analyzed. RESULTS: Of the 87 participants contacted, 43 (49%) completed the entire survey. STAR (Small Bone Innovations, Inc., Morrisville, PA) was the most preferred implant before the course with 15 individuals listing it as top preference. A large percentage of participants (67%) changed implant preferences after the course. Of the 29 participants who changed preferences, 48% switched to INBONE II (Wright Medical, Arlington, TN) and 24% to STAR. Average number of TAAs performed in the 3 months before the course was 1.3 and increased significantly in the following 3 months to 2.1. Total number of reported intraoperative complications decreased from 12 before the course to 6 after, the most common being malleolar fractures. Overall, 84% of participants indicated that the course positively changed their use and perceptions of TAA and current implant systems. CONCLUSION: The main finding of this study was that the AAOS/AOFAS TAA training course changed implant system preferences, surgical indications, number of cases performed, and complication rates among participants in the short-term.

The strength of achilles tendon repair: a comparison of three suture techniques in human cadaver tendons.

BACKGROUND: A previous study suggests the double Krackow suture (locking-loop) weave technique is nearly twice as strong as the single Bunnell or single Kessler suture repair techniques. Our hypothesis was that the strength of different repair techniques would be comparable if a similar number of suture strands cross the repair site. MATERIALS AND METHODS: Twenty-four fresh-frozen human cadaver Achilles tendons were used to test maximum strength of three suture techniques (double Bunnell, double Kessler, and double Krackow). The simulated ruptures were created in the midsubstance of the Achilles tendon, five centimeters proximal to its calcaneal insertion. All repairs were performed with No. 2 polyester (Mersilene, Ethicon, Sommerville, NJ) nonabsorbable suture in standard fashion for each technique, with four strands crossing the repair site. The tendons were then anchored to a materials testing machine (Instron, Canton, MA) through a calcaneal pin distally and a modified soft tissue clamp proximally. Tendons were loaded with continuous tension at a head speed of 0.85 cm/s. RESULTS: All repairs failed at the site of the suture knots, none pulling out through the substance of the tendon. A one-way analysis of variance was performed on the maximum force at failure of each repair technique. No statistically significant difference was noted between the double Krackow weave (199.9 +/- 20 N), the double Bunnell weave (196.2 +/- 45 N), and the double Kessler weave (166.9 +/- 51 N). CONCLUSION: We found that in a laboratory model of cadaveric Achilles tendon repairs there was no significant difference in strength between the Krackow, Bunnell, and Kessler suture techniques, when each was performed with a double suture weave. CLINICAL RELEVANCE: This is a cadaveric study that attempts to simulate the clinical parameters of Achilles tendon ruptures, repairs, and repair failures to examine the strength of different repair techniques.