Lateral Talar Station Research Articles

Lateral Trans-Fibular Total Ankle Replacement Capability in Correcting Ankle Osteoarthritis Deformities and Improving Clinical Outcomes

Category: Ankle; Ankle Arthritis; Hindfoot; Other Introduction/Purpose: Total ankle replacement (TAR) has been shown as a viable surgical option to reduce pain, improve function, and preserve ankle joint range of motion in patients with Ankle osteoarthritis (AO). Standard anterior approach TAR capability in correcting deformities is already established by several studies. However, there is a paucity of literature evaluating patient outcomes as well as the potential to correct alignment using a lateral approach TAR. Therefore, the primary objective of this study was to assess the capability of lateral trans-fibular approach TAR in correcting coronal and sagittal plane deformity and secondarily to report the ability to improve patient-reported outcomes (PROs) following lateral TAR. Methods: This IRB-approved, retrospective comparative study included 14 consecutive patients that underwent lateral trans- fibular approach TAR for end-stage AO. Average age and BMI were 63.9 years (range 43-83) and 32.7 kg/m2 (SD 7.5). All patients had received pre- and post-operative weight-bearing CT imaging on the affected foot and ankle. Foot and Ankle Offset (FAO), Talar Tilt Angle (TTA), Hindfoot Moment Arm (HMA), and Lateral Talar Station (LTS) were performed. PROs were collected pre- and post-operatively at the latest clinical follow-up including: PROMIS Global Physical Health score, the Tampa Scale of Kinesiophobia (TSK), the European Foot and Ankle Society (EFAS) score, the Pain Catastrophizing Scale (PCS) and the Foot and Ankle Ability Measure (FAAM) Daily Living Score. One-way ANOVA and Wilcoxon tests were used for comparison at each interval time period. A multivariate regression analysis was then performed to evaluate the association between change in alignment and improvements of PROs. Results: Three of 14 patients (21.4%) underwent a concomitant osseous re-alignment procedure. At an average of 16.1 months (range 11 to 24), all patients demonstrated a significant deformity correction in measurements performed: FAO (7.73% - 3.63%, p=0.031), HMA (10.93mm - 5.10mm, p=0.037), TTA (7.9o - 1.5o, p=0.003), and LTS (5.25mm - 2.83mm, p=0.018). Four of the PROs demonstrated significant improvement postoperatively: TSK (42.7-34.5, p=0.012), PROMIS Global Physical Health (46.1- 54.5, p=0.011), EFAS (5-10.3, p=0.004), and FAAM (60.5-79.7, p=0.04). PROMIS was associated (p=0.0015) with optimization of FAO (p=0.00065) and LTS (p=0.00436), R2 of 0.98). Improvements in TSK were associated with changes in the HMA (p=0.0074), R2 of 0.66. Improvements in FAAM correlated (p=0.048) with improvements in FAO (p=0.023) and TTA (p=0.029), and an R2 of 0.78. Conclusion: In this retrospective comparative cohort study, the results suggest that the lateral trans-fibular TAR can correct different aspects of AO deformity. Clinical benefit was also demonstrated by the impacted PROs, particularly TSK, PROMIS Global Physical Health, EFAS, and FAAM Daily Living. Direct and strong correlations between deformity correction measurements and the significantly improved PROs were found. The obtained data might help surgeons when planning treatment and may serve as the basis for future comparative prospective studies.

Agreement between semiautomatic and manual measurement of selected parameters on weight-bearing computed tomography images in total ankle replacement: a retrospective study

Objective: To assess the agreement between semiautomatic 3D measurements and manual measurements derived from WBCT images in patients with end-stage ankle osteoarthritis (AO) who underwent total ankle replacement (TAR). Methods: In this retrospective, IRB-approved study (ID #201904825), we evaluated patients who underwent TAR via the lateral trans-fibular approach for end-stage ankle OA. The study included 14 ankles from 14 patients. Raw multiplanar data were analyzed using CubeVue® software. Lateral talar station (LTS) was obtained in the sagittal plane, while hindfoot moment arm (HMA) and talar tilt angle (TTA) were calculated in the coronal view. Semiautomatic 3D measurements were performed using Disior® software. Intra-rater reliabilities were analyzed using the intraclass correlation coefficient (ICC). Agreement between methods was tested with Bland-Altman plots. Each measurement was assessed using the Wilcoxon signed-rank test. Alpha risk was set to 5% (α=0.05). P-values of ≤0.05 were considered significant. Results: ICC-measured reliabilities ranged from moderate to almost perfect for manual and semiautomatic WBCT measurements in the preoperative and postoperative groups for HMA and LTS. There was high correlation between parameters calculated from manual and semiautomatic measurements, and strong agreement between the readers and software in both groups. Conclusions: Manual (M) and semiautomatic (SA) 3D measurements expressed excellent agreement for pre- and postoperative groups, indicating a high correlation between the parameters calculated and strong agreement between the readers and the software in both groups. Level of Evidence III; Therapeutic Studies; Comparative Retrospective Study.

Does Sagittal Tibiotalar Alignment of TAR Predict Failure?

Category:Ankle ArthritisIntroduction/Purpose:The long term outcome of total ankle replacement is contingent on restoring the anatomic tibiotalar alignment of the ankle joint. Prior studies have mainly looked at the effect of coronal and hindfoot alignment of TAR on outcome and failure with few studies focusing on the effect of sagittal tibiotalar alignment. From these, we know that sagittal alignment has a greater impact on joint mechanics and that proper positioning of the talar component in the sagittal plane results in greater postoperative pain relief and better functional outcome, especially ankle range of motion. The goal of this study was to define a sagittal radiographic value that predicts failure in TAR.Methods:We analyzed the data of a retrospective patient cohort of consecutive TAR patients, which were treated from 2004 and 2011. Patients with two types of prosthesis were included, Salto Talaris (fixed bearing) and STAR (mobile bearing). All measurements were completed by two blinded observers, including the sagittal distal tibial articular angle (sDTAA), the lateral talar station (LTS) and the talar component inclination angle (γ angle). A total of 90 patients were included, 51 were male and 39 female patients. Seventy-seven patients received a Salto and 13 patients a STAR prosthesis. The average age was 63.7 years.Results:The mean sDTAA was 83.9 degrees and the mean γ angle was 21 degrees, both without significant difference in the two different prosthesis designs. A significant association (p=0.03) between post-op LTS as a continuous variable per unit increase and clinical failure was demonstrated, which included all the revision cases, with an odds ratio of 1.25. In addition a significant association (p=0.03) between increased LTS and sDTAA change of >5°, which is indicative of anterior subsidence, was shown. This was associated with an odds ratio of clinical TAR failure of 1.27.Conclusion:The abnormal radiographic post-op lateral talar station appears to predict clinical TAR failure and correlates with the abnormal sDTAA; the anterior translated talus loads the anterior tibia leading to anterior subsidence of the prosthesis. Limitation of this study is the inclusion of two different types of prosthesis designs.

Mid-Term Results after Lateral Transfibular Approach Total Ankle Arthroplasty

Category:Ankle Arthritis; AnkleIntroduction/Purpose:Continued improvements in total ankle arthroplasty (TAA) implant design have led to promising clinical outcomes. The lateral transfibular approach TAA allows for excellent visualization of the center of rotation of the ankle and allows for correction of rotational and sagittal deformity by shortening or lengthening of the fibula. Furthermore, the curved implant design allows for minimal bony resection. The purpose of this study is to report the medium-term clinical and radiographic results for consecutive patients who underwent the lateral approach TAA.Methods:IRB approval was obtained for this study. Consecutive patients who underwent lateral approach TAA for tibiotalar arthritis by a single surgeon were enrolled on a prospective basis from January 2013 to June 2015. This time period represented the initial case series of TAA performed by the surgeon. Patient reported outcomes (PROs) were collected including the Ankle Osteoarthritis Scale (AOS), 12-item short-form survey (SF-12), and Visual Analogue Pain Scale (VAS). The need for subsequent procedures was recorded. Radiographs were evaluated for preoperative and postoperative alignment using the lateral distal tibial angle (LDTA), tibiotalar surface angle (TTS), anterior distal tibia angle (ADTA), and the lateral talar station (LTS). Radiographs were also evaluated for the development of peri-implant lucency and subsidence. Data was tested for normality. T-tests were used to determine differences between preoperative data and postoperative data. A p<0.05 was considered significant.Results:53 patients who underwent 59 TAA procedures were included. Average follow-up was 5.7 +/- 0.9 years. Average age was 53 +/- 7.0. Comorbidities included smoking (11/53), diabetes (6/53), and prior procedures (33/53). Sixteen ankles (27%) underwent one or more subsequent procedures including gutter debridement (7/59), debridement for periprosthetic infection (3/59), and removal of hardware (7/59). All fibular osteotomies healed. Four ankles had asymptomatic peri-implant lucency or cysts (4/59). No patients had subsidence or required revision of the tibial or talar components. Coronal and sagittal alignment were significantly improved for all measures (p<0.05). VAS scores improved from a mean of 7.5 preoperatively to 1 at final follow- up (p<0.0001). SF-12 physical component scores improved from 34 to 41.5 (p=0.0227). AOS scores improved from 54.8 to 19.1 (p<0.0001).Conclusion:At medium term follow-up, patient reported outcomes remain significantly improved in patients after lateral approach TAA. There were very few radiographic findings of lucency and cyst formation, and all of these were asymptomatic. No revision of metal implants was required. Excellent deformity correction was achieved. The rate of subsequent procedures was high, although the rate of actual component revision was 0%. Lateral approach TAA appears to have overall good outcomes at medium term follow-up.

Total Ankle Arthroplasty Radiographic Alignment Comparison Between Patient-Specific Instrumentation and Standard Instrumentation.

Several benefits are published supporting patient-specific instrumentation (PSI) in total ankle arthroplasty (TAA). This study seeks to determine if TAA with PSI yields different radiographic outcomes vs standard instrumentation (SI). Sixty-seven primary TAA patients having surgery using PSI or SI between 2013 and 2015 were retrospectively reviewed using weightbearing radiographs at 6-12 weeks postsurgery. Radiographic parameters analyzed were the medial distal tibia angle (MDTA), talar-tilt angle (TTA), anatomic sagittal distal tibia angle (aSDTA), lateral talar station (LTS), and talar component inclination angle (TCI). A comparison of the 2 groups for each radiologic parameter's distribution was performed using a nonparametric median test and Fisher exact test. Furthermore, TAAs with all radiographic measurements within acceptable limits were classified as "perfectly aligned." The rate of "perfectly aligned" TAAs between groups was compared using a Fisher exact test with a significance of .05. Of the 67 TAAs, 51 were done with PSI and 16 with SI. There were no differences between groups in MDTA (P = .174), TTA (P = .145), aSDTA (P = .98), LTS (P = .922), or TCI angle (P = .98). When the rate of "perfectly aligned TAA" between the 2 groups were compared, there was no significant difference (P = .35). No significant radiographic alignment differences were found between PSI and SI implants. This study showed that both techniques achieve reproducible TAA radiographic coronal and sagittal alignment for the tibial component when performed by experienced surgeons. The talar component's sagittal alignment is similar whether or not PSI was used but is noticeably different from normal anatomic alignment by design. Level III, retrospective cohort study using prospectively collected data.

Anterior distal tibial plafond-plasty for the treatment of posttraumatic ankle osteoarthritis with anterior translation of the talus

Posttraumatic ankle osteoarthritis (OA) represents a significant challenge to orthopedic surgeons, especially in cases of anterior talar translation and concomitant impaction of the anterior distal tibial plafond. The aim of this study was to evaluate the clinical outcomes of an intra-articular osteotomy for the management of these patients. A total of 21 patients meeting our criteria were retrospectively reviewed. Sixteen patients sustained initial pilon fractures, while five patients had Weber type C ankle fractures. Anterior distal tibial plafond-plasty was performed to address the impaction and anterior translation of the talus. The American Orthopedic Foot and Ankle Society (AOFAS) hindfoot score and visual analog scale (VAS) score were utilized as clinical outcomes. The lateral talar station (LTS), tibial lateral surface (TLS) angle, tibial anterior surface angle and talocrural angle were evaluated pre- and postoperatively. The modified Kellgren-Lawrence score was used for the evaluation of sagittal ankle OA. The average age at surgery was 35 years, and the average follow-up duration was 34 months. The AOFAS hindfoot score increased from 26 to 71 (p < 0.01), and the VAS score improved from 7 to 2 (p < 0.01). The LTS improved from 9.0 to 2.3 mm (p < 0.01), and the TLS angle improved from 72° to 81° (p < 0.01). Of the 21 patients, 18 showed improvement in or no worsening of ankle OA on the sagittal plane, while 3 developed advanced ankle OA. A congruent ankle joint on the sagittal plane could be achieved by anterior distal tibial plafond-plasty. This is a valuable treatment option for the salvage of posttraumatic ankle OA with anterior translation of the talus.

Mobile Anatomical Total Ankle Arthroplasty-Improvement of Talus Recentralization.

Introduction: Total ankle arthroplasty (TAA) is becoming a more frequent treatment option for end-stage ankle osteoarthritis (OA) as outcomes measures are improving. However, there is concern that malalignment of TAA can result in premature failure of the implant. One of the malalignment issues is the talar sagittal malposition. However, a consensus on the significance of the sagittal translation of the talus in TAA is yet to be established. The aim of this study was, therefore, to clarify whether talus OA subluxation is normalized after the implantation of a mobile TAA. Methods: Forty-nine consecutive patients with symptomatic end-stage ankle OA underwent 50 cementless three-component mobile-bearing VANTAGE TAA with 21 right ankles (42%) and 29 left ankles (58%). Clinical and radiographic outcomes were assessed: Clinical variables: American Orthopedic Foot and Ankle Society (AOFAS) ankle-hindfoot score (0–100), visual analogue scale (VAS, 0–10), and ankle range of motion (ROM). Radiological variables: medial distal tibial articular angle (mDTAA), anterior distal tibial articular angle (aDTAA) and lateral talar station (LTS). Results: The clinical results showed the mean improvement in AOFAS hindfoot score from 42.12 ± SE 2.42 (Range: 9–72) preoperatively, to 96.02 ± SE 0.82 (Range: 78–100) at a mean follow-up of 12 months, with a highly statistically significant difference (p < 0.00001). Pain score (VAS) was 6.70 ± SE 0.28 (Range 0–10) preoperatively, and 0.26 ± SE 0.12 (Range: 0–3) at 12-month follow-up, with a highly statistically significant difference (p < 0.00001). ROM measurements preoperatively showed a mean of 22.55° ± SE 1.51° (Range: 0–50°), which showed a statistically significant improvement (p < 0.0001) to 45.43° ± SE 1.56° (Range: 25–60°) 12 months postoperatively. The radiological analyses revealed the following results: On the coronal view, the mDTAA preoperatively was 88.61 ± SE 0.70 (Range: 78.15–101.10), which improved to 89.46 ± SE 0.40 (Range: 81.95–95.80) at 12 months (not statistically significant—p = 0.94). On the sagittal view, the preoperative values of the aDTAA showed 82.66 ± SE 0.84 (Range: 70.35–107.47), which improved to 88.98 ± SE 0.47 (Range: 82.83–96.32) at 12 months postoperatively, with a highly statistically significant difference between preoperative and 12-months values (p < 0.00001). The mean LTS values for all patients were 3.95 mm ± SE 0.78 (Range: −11.52 to 13.89) preoperatively and 1.14 mm ± SE 0.63 (Range: −10.76 to 11.75) at 12 months, with a statistically significant difference between preoperative and 12-month follow-up (p = 0.01). The review of the radiological TAA osteointegration at 12 months showed no cases of loosening of the implanted TAAs. Two cases (4%) showed a radiolucency and one case (2%) a cyst on the tibial component; no cases had a change on the talar component. No TAA complication/revision surgeries were documented. Conclusion: In the present study, the lateral talar station of anteriorly subluxated ankles showed a significant improvement, i.e., physiological centralization of the talus, in the postoperative period when a mobile-bearing TAA was performed. The anterior/posterior congruency between the talar component and the mobile polyethylene insert of the mobile-bearing VANTAGE TAA allows the sagittal translation of the talus relative to the flat tibial component, reducing the prosthesis strain and failure.

Clinical evaluation of arthrodesis with Ilizarov external fixator for the treatment of end-stage ankle osteoarthritis: A retrospective study.

To analyze the efficacy of arthrodesis with Ilizarov external fixator for the treatment of end-stage ankle osteoarthritis.This retrospective study included 88 patients with end-stage (stage-3) ankle osteoarthritis according to Morrey–Wiedeman classification who underwent arthrodesis with Ilizarov external fixator from January 2016 to January 2019. There were 47 males and 41 females with a mean age of (57.21 ± 7.12) years old (range 49–76). Outcomes were measured by the American Orthopaedic Foot and Ankle society (AOFAS) Ankle Hindfoot Scale, Visual Analog Scale (VAS) pain scores, complications, subjective satisfaction, ankle function, correction of deformity, and complications.With an average follow-up of (13.50 ± 5.41) months (range 10–21), all 88 patients returned for final follow-up. All patients achieved bony healing with a success rate of 100%. Mean postoperative healing time (3.56 ± 1.04) months (range 3–6). Two patients developed sinus tract infection, delayed healing in 1 patient, and 2 patients had pain and swelling again in the ankle joint. No serious complications occurred in other patients. All the patients evaluated with the VAS scores and AOFAS scores at final follow-up showed significant improvement (P < .05). Through imaging analysis, medical tibial talar angle (MTTA) improved from (85.76 ± 6.01) degrees to (88.98 ± 1.35) degrees postoperative. Lateral talar station (LTS) decreased from (5.32 ± 3.81) mm to (2.71 ± 2.62) mm after operation (P < .05). The overall satisfaction of patients is 88.64%.In the treatment of end-stage ankle osteoarthritis, arthrodesis with Ilizarov external fixator can achieve good radiological and clinical outcomes with low prevalence of ankle joint malalignment and high fusion rates and satisfaction.

Study of the radiographic parameters of normal ankles

Objective: The authors carried out a bibliographic search for the radiographic parameters used to determine tibiotalar joint alignment, and suggest a set of parameters that constitute the minimum radiographic evaluation sufficient for the proper assessment of tibiotalar alignment. Methods: The search was conducted between May 2019 and January 2020 on the online platforms PudMed and Google Scholar with the following terms, used separately or jointly: “ankle arthritis, radiographic measurement, ankle alignment, alignment, anterior ankle instability, X-ray, and ankle injury”. Results: We selected twelve studies evaluating radiographic patterns of normal ankles, and identified a total of 15 radiographic measurements. Conclusion: The authors believe that a minimum radiographic assessment of tibiotalar alignment should include the following parameters on the anteroposterior radiograph: the distal tibial articular angle, the talar tilt and talus center migration. On the lateral radiograph, it should include: lateral distal tibial angle and lateral talar station. Level of Evidence V; Diagnostic Study; Expert Opinion.

Does surgical approach affect sagittal plane alignment and pilon fracture outcomes?

PurposeSagittal plane alignment beyond articular reduction and its effect on clinical outcomes has not been emphasized. Surgical approach may influence a surgeon's ability to correct the sagittal plane alignment. The purpose of our study was to evaluate how surgical approach impacts anterior distal tibial angle (ADTA) and lateral talar station (LTS). Our hypothesis was that the anterolateral (AL) approach would improve the sagittal plane parameters due to the primary plate placement. Patients and methodsA retrospective review was performed on patients who underwent operative management for pilon fractures at 2 ACS Level 1 Academic Trauma Centers. Clinical data points including demographics, comorbidities, AO/OTA classification, surgical approach, and complications were recorded. Quality of reduction was measured using the ADTA, lateral distal tibia angle (LDTA), and lateral talar station (LTS) from radiographs. Results580 pilon fractures met inclusion criteria. When compared to the AL approach, the modified anteromedial (AM) approach had decreased rates of local wound care, and unplanned reoperations. The AM approach had increased rates of superficial infection, deep infection, non-union, and amputations. There was no difference in ADTA, LDTA, or LTS between the AM and AL approach (P = 0.49, P = 0.41, P = 0.85). There was a difference in LTS with tobacco users (P = 0.02). ConclusionsThe sagittal plane alignment does not appear to be affected by the surgical approach. Therefore, the surgical approach to pilon fractures should be based on the fracture pattern and the patient's soft tissue envelope. This study shows that the AM is a relatively safe and effective approach to complex fractures and the surgeon should consider the specific fracture pattern and patient soft tissue envelope when choosing the specific approach.

Metal artifact reduction MRI for total ankle replacement sagittal balance evaluation

BackgroundRestoration of anatomical relationship between talus and tibia is crucial for longevity of total ankle replacement (TAR). Weight-bearing (WB) radiographs are the standard for evaluating the sagittal balance alignment, but are prone to rotational misalignment and altered measurements. Metal artifact reduction sequence (MARS) MRI allows visualization of periprosthetic landmarks and alignment of the image plane to the true sagittal axis of the implant. The purpose of this study was to compare TAR sagittal balance measurements on MARS MRI and WB radiographs. MethodsTwenty-three subjects with TAR [10 men/13 women, age 60 (41–73) years; 13 (3–24) months post-op] underwent MARS MRI and standard lateral WB radiographs. Standardized MARS MR images were aligned to the sagittal talar component axis. Three observers performed sagittal balance alignment measurements twice in an independent, random and blinded fashion. Lateral Talar Station (LTS), tibial axis-to-talus (T-T) ratio and normalized tibial axis-to-lateral-process (T-L) distance were measured. Concordance correlation coefficients (CCC) and intraclass correlation coefficients (ICC) were used for statistical analysis. In addition, mixed effects linear models were employed to assess overall concordance of the two image types. ResultsThe intraobserver agreement was excellent for radiographic (CCC=0.96) and MRI (CCC=0.90–0.97) measurements. Interobserver agreements were good-to-excellent with overall slightly higher agreements for MRI (ICC=0.78–0.94) than radiography (ICC=0.78–0.90) measurements. The T-T ratios of radiographs and MRI showed a high degree of concordance, whereas LTS was significantly lower on MRI when compared with radiographs, and T-L distance showed notable disagreement between the two imaging types. ConclusionSagittal balance measurements performed on standardized weight-bearing radiographs and standardized MARS MRI demonstrate substantial correlation and similarity. Given its high intra and interobserver agreement, MARS MRI may be helpful for the evaluation of TAR sagittal balance.Level of evidence: Level II - Prospective Comparative Study.

Does Patient-specific Instrumentation Yield Better Component Position than Standard Instrumentation in Total Ankle Arthroplasty?

Category: Ankle Arthritis Introduction/Purpose: The unique anatomy and biomechanics of the ankle joint have made total ankle arthroplasty (TAA) challenging over the past few decades. Final implant position and successful soft tissue balancing are key components to the longevity of total ankle implants. Preoperative computer navigation, templating, and patient-specific instrumentation (PSI) have shown promising results in total ankle replacement with accurate and reproducible radiographic outcomes. Recent data has also suggested that even experienced surgeons benefit from the improved time efficiency of PSI. The purpose of this study is to determine if radiographic outcomes differ between patients undergoing TAA with PSI and those who undergo TAA with standard instrumentation (SI). Methods: The first 67 consecutive patients who underwent primary Infinity total ankle arthroplasty (TAA) at 2 North American sites between 2013 and 2015 were reviewed in a prospective observational study. All TAA’s were performed by one of four fellowship-trained foot and ankle surgeons. Demographic, radiographic, and functional outcome data was collected preoperatively, at 6-12 months postoperatively, and annually thereafter. The radiographic variables measured were the medial distal tibial angle (MDTA), talar tilt angle (TTA), lateral talar station (LTS), sagittal distal tibial articular angle (sDTAA), and the gamma angle. Acceptable intervals for each parameter were selected and TAAs were then categorized as being “correctly aligned” or “not correctly aligned” for all the parameters described. The rate of “correctly aligned” TAA’s was compared between cases with PSI and those with SI. Fisher’s exact test was used to analyze difference by groups. A significance of 5% was used. Results: Of a total of 67 TAAs included, 51 were in the PSI group and 16 in the SI group. No significant statistically differences were found between PSI and NPSI regarding MDTA (p=0.174), LTS (p=0.922), sDTAA (p=0.986), gamma angle (p=0.252) and TTA (p=0.145). We did not find a significant statistical difference in the rate of “correctly aligned TAR” when we compared both groups (p=0.35). Conclusion: This study suggests that both PSI and SI provide accurate and reproducible TAA radiographic alignment when performed by experienced surgeons. In view of previously published data demonstrating high levels of reproducibility for PSI in TAA, these data also suggest that PSI may offer a means for less experienced surgeons to achieve radiographic results similar to those achieved by experienced surgeons. It also suggests that experienced surgeons may not need to use PSI to achieve satisfactory implant alignment, though improved time efficiency with PSI, as demonstrated in other studies, may still be of benefit for experienced surgeons.

Predicting Failure in Total Ankle Arthroplasty. A COFAS study

Category: Ankle Arthritis Introduction/Purpose: Total ankle arthroplasty (TAA) and ankle arthrodesis (AA) are standard treatment modalities for end-stage ankle osteoarthritis. The total ankle arthroplasty (TAA) anatomical alignment is critical for the longevity of total ankle components. Coronal and sagittal malalignment results in altered joint mechanics and reactive forces that result in implant failure. Also, to our knowledge, tibial component sizing in the sagittal plane has been addressed in knee arthroplasty literature, but not in ankle arthroplasty literature. Based on these parameters, we developed a novel radiographic predictive score for failure in TAA (RPSFT). Methods: A retrospective review performed on the COFAS database, selecting for all total ankle replacements done at a single institution between September 2004 and June 2015. Those with complete series of anteroposterior and lateral standing ankle radiographs, both preoperative and postoperative and a minimum of 1 year of follow-up, were included. We performed a multivariate logistic regression, using the medial distal tibial component angle, lateral talar station, talar tilt angle, and the absence of posterior under= or overhang of the tibial component in the first post-operative radiographs. These parameters were used to develop a RPSFT. Binomial regression was used to determine each variable’s weight in the RPSFT and assigned a corresponding score value. A univariate logistic regression was estimated, using the RPSFT as the independent variable and mechanical failure as the dependent variable. Then a Receiver-Operating Characteristic curve was constructed and the probability of failure for each possible score was estimated. Results: Of a total of 296 TAAs, 146 were included, and 8 TAAs required revision (5%). TAA revision was defined as a reoperation to remove one or both metal components, or amputation. According to our predictive score, if all the parameters are within established normal ranges (17 points) the TAA failure probability (TFP) is 2% [0-0.1] p&lt;0.01. If none of them are obtained (0 points) the TFP rise to 42% p&lt;0.01 (see attached table). Time to TAA failure averaged 4.4 years and ranged from 1.4 to 9.6 years. Conclusion: Our model suggests that a coronal and sagittal alignment and absence of tibial implant under/overhang are of vital importance to prevent TAA failure. To our knowledge, this is the first study that presents a predictive score for failure in TAA using postoperative ALSAR. Further data analyses are ongoing and may expand our predictive model to include other radiographic parameters.

Radiographic Analysis of Total Ankle Replacements

Category: Ankle Arthritis Introduction/Purpose: Total ankle replacements (TAR) are an increasingly common treatment for end-stage ankle arthritis but evidence on optimal alignment is not as well-established as in the hip and knee arthroplasty literature. Many believe that restoration of coronal and sagittal alignment is critical, while others suggest malalignment within a certain range has no impact on failure (Braito et al. 2015). There is controversy on the ideal TAR component positioning to minimize failure and requiring revision surgery. In this study we examine 9 radiographic measures of TARs, 6 of which have previously been described for TARs, 1 commonly used on preoperative ankles, and 2 novel measures on a database of 146 TARs to identify predictors of TAR re-operation. Methods: A retrospective review was performed on the Canadian Orthopaedic Foot and Ankle Society (COFAS) database of ankle arthritis, selecting for all total ankle replacements done at a single institution by one of three fellowship-trained foot and ankle surgeons between September 2004 and June 2015. Those with complete series of anteroposterior and lateral standing ankle radiographs both preoperative and postoperative, and minimum of 1 year of follow-up were included. Measurements were performed on the postoperative radiographs and included: coronal and sagittal distal tibial component angles, talar center migration, talar tilt angle, lateral talar station, tibial axis-talus ratio, talar component gamma angle, anterior and posterior tibial component overhang and underhang. Standard descriptive statistical methods were used to analyze the data. Results: Of a total of 296 TARs, 146 were included and 14 TARs failed (9.6%), defined as requiring re-operation, 8 of which were metal-component revisions (5%). The TARs were stratified into those with measurements within previously published normal values and those that fall outside that range. Time to failure ranged from 1.4 to 9.6 years. Our preliminary data analysis showed that TARs with coronal distal tibial component angles between 87-93 degrees demonstrated an odds ratio of 0.11 for re-operation compared with those beyond that range, p=0.003. TARs with talar tilt angles of 0 degrees demonstrated an odds ratio of 0.24 for re-operation compared with those whose talar tilt was not zero, p=0.02. Conclusion: Post-operative coronal alignment of TARs, namely distal tibial component angle and talar tilt, appear to be associated with TAR-reoperation. Specifically, if the measurements are within previously described normal limits, the odds ratio for re-operation is low and statistically significant. Further data analysis is underway and may demonstrate more parameters of significance in predicting TAR failure.

Effect of Preoperative Deformity on Arthroscopic and Open Ankle Fusion Outcomes.

Coronal deformity is considered a relative contraindication for arthroscopic ankle fusion. This study assessed whether preoperative coronal ankle joint deformity influenced the outcome of arthroscopic ankle fusion. Ninety-seven patients had 62 arthroscopic and 35 open ankle fusions between 2005 and 2012. Clinical outcomes were prospectively recorded with use of the Ankle Osteoarthritis Scale (AOS) and Ankle Arthritis Scale (AAS) preoperatively and at 6, 12, and 24 months and final follow-up. Radiological alignment was measured using the tibiotalar angle, the tibial plafond angle, the lateral talar station, and the lateral tibiotalar angle. Both groups had the same demographics. Preoperative deformity was the same regarding sagittal alignment and overall coronal alignment, but the arthroscopic group had less tibial deformity (tibial plafond angle range 0-19 degrees vs 0-43 degrees). At final follow-up, the mean AOS was 34.2 for arthroscopic (95% confidence interval [CI], 23.3-45.2) vs 33.9 for open (95% CI, 17.8-49.9). The AAS at final follow-up was 26.0 for arthroscopic (95% CI, 21.0-31.0) vs 27.5 for open (95% CI, 19.7-35.2). Both groups had the same tibiotalar angle, lateral talar station, and lateral tibiotalar angle at follow-up. Regression analyses revealed no influence of type of surgery, preoperative deformity, postoperative radiological alignment, age, sex, body mass index, smoking status, etiology of the arthritis, and need for bone grafting on outcome scores (all P > .05). Arthroscopic and open ankle fusion yielded equivalent results for both patient-reported outcome measure and radiographic alignment in patients with coronal and sagittal joint deformity. Patients with higher tibial plafond angles more often underwent open fusion. III, comparative series.

Joint space widening may be a paradoxical pathologic feature of early ankle arthritis

Category: Ankle, Ankle Arthritis Introduction/Purpose: Joint space narrowing and bony spur are typical pathologic feature of early ankle osteoarthritis. The meaning of joint space widening has never been discussed in previous literature. However, we found some osteoarthritic ankles which showed joint widening with diffuse spur change.(Fig.1) We hypothesized that joint space widening may be caused by malpositioning of the talus which may lead to degenerative arthritis. The purpose of this study were to investigate the radiological abnormalities in ankles with joint space widening. Methods: In order to define joint space widening and anterior subluxation of the talus, we included 72 ankles (66 people) with no abnormalities on plain radiographs into control group. We measured joint space and lateral talar station(LTS) on plain weight- bearing radiographs.(Fig.2) The 95% prediction interval of joint space (2.4 mm to 4.2 mm) and the LTS (-0.9 mm to 3.8 mm) in the control group were regarded as a normal range. The joint space widening was defined when the joint space was wider than 4.2 mm, and the anterior subluxation of talus was defined when the LTS was larger than 3.8 mm. Thirty-two ankles (29 people) with the joint space widening which underwent operation in our clinic between 2009 and 2014 were included in patient group. Ankle instability was determined on stress radiographs (Fig.2). In the patient group, we investigated the anterior subluxation of talus and the ankle instability, and the sites of spur in conventional CT. Results: The average age was 26 years (range:18 - 35) in the control group and 33 years (range:16 - 71) in the patient group. The mean joint space of the patient group was 4.7 mm (range: 4.3 mm to 6.0 mm). In the patient group, the LTS showed a mean of 6.4 mm (range 3.9 mm -10.7 mm). Because all the LTS in the patient group was over the 3.8 mm, the anterior subluxation of talus was showed in all ankles of the patient group. In the patient group, 31 ankles (97%) showed instability on anterior stress radiograph and 24 ankles (75%) showed instability on varus stress radiograph. All ankles in the patient group showed spurs on 4 sides of ankle, anterior, posterior, medial and lateral side. Conclusion: This study showed that paradoxical joint space widening may be a pathologic feature of early ankle arthritis which had diffuse spur change, anterior displacement of the talus and ankle instability.

Sagittal Distal Tibial Articular Angle and the Relationship to Talar Subluxation in Total Ankle Arthroplasty

Longevity of total ankle replacement (TAR) depends heavily on anatomic alignment. The lateral talar station (LTS) classifies the sagittal position of the talus relative to the tibia. We hypothesized that correcting the sagittal distal tibial articular angle (sDTAA) during TAR would anatomically realign the tibiotalar joint and potentially reduce the risk of prosthesis subluxation. The LTS (millimeters) and sDTAA (degrees) were measured twice by 2 blinded observers using weight-bearing lateral ankle radiographs obtained before (n = 96) and after (n = 94) TAR, with excellent interobserver and intraobserver reliability (correlation coefficient >0.9). Preoperative LTS was as follows: anterior (60.4%), posterior (27.1%), and neutral (12.5%). A strong preoperative correlation was found between LTS and sDTAA (r = 0.81; P < .0001). In ankles that were initially anterior and became less anterior postoperatively (n = 41), LTS decreased from an average 8.1 mm to 6.5 mm and the LTS changed 1.1 mm per degree of sDTAA change. In ankles that were initially posterior (n = 25), LTS increased from an average of -5.1 mm to -2.8 mm and the LTS changed 0.6 mm per degree of sDTAA change. The correlation between LTS and sDTAA was reduced postoperatively (r = 0.62; P < .0001). Our results suggest that rather than following generic recommendations, the surgeon should customize the sagittal distal tibial cut to the individual patient based on the preoperative LTS in order to achieve neutral TAR alignment. Level III, retrospective comparative series.

Metal Artifact Reduction MRI for Sagittal Balance Evaluation of Total Ankle Arthroplasty

Category: Ankle Arthritis Introduction/Purpose: Surgical restoration of the anatomical relationship between talus and tibia is considered crucial for longevity of total ankle arthroplasty (TAA). Weight-bearing (WB) radiographs are the current standard for evaluating the sagittal balance alignment, which are, however, prone to rotational misalignment and potentially altered measurements. Metal artifact reduction sequence (MARS) MRI is a cross-sectional technique that minimizes implant-induced artifacts and affords the visualization of bone-implant interfaces and periprosthetic bone without distortions. Although not weight-bearing, MARS MRI offers the ability to align the image plane to the true sagittal axis of the talar implant and anatomically correct measurements. Therefore, the purpose of this study was to compare sagittal balance alignment measurements on MARS MR images and standard WB radiographs in patients with TAA. Methods: In this IRB-approved, prospective study, 23 subjects [10 men/13 women, age 60(41-73) years; 13(3-24) months post- op] underwent MARS MRI and standard lateral WB radiographs. Standardized MARS MR images were obtained in alignment to the sagittal talar component axis and use of a boot-shaped MRI coil. Maximum-intensity-projection MR images that resemble lateral radiographs were created to bring anatomic landmarks, such as lateral talar process, talonavicular joint line, talar implant, tibial shaft, and posterior talus into one single image. Three board-certified foot ankle surgeons performed sagittal balance alignment measurements twice in an independent, random and blinded fashion. The second set of measurements was obtained 1 months after the first assessment. In accordance with published measurements, lateral talar station (LTS), tibial axis-to-talus (T-T) ratio, and normalized tibial axis-to-lateral-process (T-L) distance were measured. Pearson correlation coefficient (r), Concordance-Correlation-Coefficient (CCC) and Intraclass-Correlation-Coefficient (ICC) were used for statistical analysis. Bonferroni-corrected p-values ≤ 0.01 were considered significant. Results: The intra-observer agreement was excellent for radiographic (CCC = 0.93 - 0.97) and MRI (CCC = 0.90 - 0.97) measurements. Inter-observer agreements were good-to-excellent with overall higher agreements for MRI (ICC = 0.76 - 0.93) than for radiography (ICC = 0.58 - 0.95) measurements. There was statistically significant inter-method correlation between radiographic and MRI measurements including LTS (r=0.83, p &lt; 0.001), T-T ratio (r=0.86, p &lt; 0.001) and normalized T-L distance (r=0.72, p &lt; 0.001). The T-T ratios of radiographs and MRI were statistically not different (p=0.36), whereas LTS and normalized T-L distance were significantly lower on MR images when compared with radiographs (p &lt; 0.001). Conclusion: Sagittal balance measurements performed on standardized weight-bearing radiographs and standardized MARS MR images demonstrate substantial correlation and similarity. Given its high inter- and intra-observer agreement, MARS MRI may be helpful for the evaluation of sagittal balance following TAA.

Lateral Talar Station

The sagittal relationship of the talus to the tibial shaft can prove invaluable to the orthopedist in understanding and effectively treating ankle pathologies such as ligamentous laxity and ankle arthritis. Any useful radiographic analysis tool to assess the lateral position of the talus must be employable reliably in the clinical setting. Previously published measurements to assess the lateral translational relationship of the talus relative to the tibial axis may not be available in the clinical setting or may be subject to significant inaccuracies. We have defined a sagittal talar position measurement (lateral talar station; LTS), which we postulated could be used reproducibly on clinical radiographs by the orthopedist to define the position of the talus as it relates to the anatomic tibial axis. In addition, we defined the normal range of the LTS measurement. A retrospective cohort of patients (121 ankles, 104 patients) who presented to our clinic with foot pain between 2005 and 2011 was evaluated for inclusion in the study. Exclusion criteria included patients with ankle trauma, instability, prior ankle surgery, or radiographic evidence of ankle osteoarthrosis. The final cohort consisted of 82 ankles. The LTS was measured digitally for each subject on weight-bearing lateral ankle radiographs by 3 observers. The mean LTS and standard deviation was determined for the entire cohort. In addition, as a means of validating our methodology, we performed an assessment of interobserver and intraobserver reliability in terms of the LTS measurements. The LTS measurements for the entire cohort fit a Gaussian distribution with a mean of 1.17 mm (SD = 0.9893 mm). Interobserver intraclass coefficients for 2 observers (medical student and radiologist) and intraobserver intraclass coefficients for 1 reader (orthopaedic surgeon) indicated excellent reliability, being above 0.9. The LTS was a reliable measure that could be used on weight-bearing lateral ankle radiographs to define sagittal position of the talus in a clinical setting. The normal distribution for the LTS was described in our study population. Level IV, case series.