Foot & Ankle International

Few authors have investigated patients’ expectations from foot and ankle surgery. In this study, we aimed to examine relationships between patients’ preoperative expectations and their demographic and clinical characteristics. We hypothesized that patients with more disability and those with anxiety or depressive symptoms would have greater expectations.

All adult patients scheduled for elective foot or ankle surgery by 1 of 6 orthopaedic foot and ankle surgeons were screened for inclusion over 8 months. Preoperatively, all patients completed the Hospital for Special Surgery Foot & Ankle Surgery Expectations Survey in addition to the Foot & Ankle Outcome Score (FAOS), Short Form (SF)–12, Patient Health Questionnaire (PHQ)–8, Generalized Anxiety Disorder 7-item scale (GAD-7), and pain visual analog scale (VAS). The expectations survey contained 23 expectations categories, each with 5 answer choices ranging from “I do not have this expectation” to “complete improvement” expected. It was scored from 0 to 100, with higher scores indicating more expectations. Differences in expectations relating to numerous patient demographic and clinical variables were assessed. In total, 352 patients with an average age of 55 ± 15 (range, 18-86) years were enrolled.

Expectations scores were not related to age (P = .36). On average, women expected to achieve complete improvement more often than men (P = .011). Variables that were significantly associated with higher expectations scores (P < .05) included nonwhite race, use of a cane or other assistive device, and greater medical comorbidity. Worse function and quality of life (as assessed by all FAOS subscales and the SF-12 physical and mental components), more depressive and anxiety symptoms, and higher pain VAS scores were associated with higher expectations scores and more expectations (P < .01 for all).

The results of this study may help inform surgeons’ preoperative discussions with their patients regarding realistic expectations from surgery. Generally, patients with worse function and more disability had higher expectations from surgery. Addressing these patients’ expectations preoperatively may help improve their ultimate satisfaction with surgery.

Level II, cross sectional study.

Post-traumatic osteoarthritis (PTOA) is responsible for the majority of cases of ankle arthritis. While acute and end-stage intra-articular inflammation has previously been described, the state of the joint between fracture healing and end-stage PTOA remains undefined. This study characterized synovial fluid (SF) composition of ankles after bone healing of an intra-articular fracture to identify factors that may contribute to the development of PTOA.

Of an original 21 patients whose SF was characterized acutely following intra-articular ankle fractures, 7 returned for planned hardware (syndesmotic screw) removal after bone healing (approximately 6 months) and consented to a second bilateral SF collection. SF concentrations of 15 cytokines and matrix metalloproteinases (MMPs) and 2 markers each of cartilage catabolism (CTXII and glycosaminoglycan) and hemarthrosis (biliverdin and bilirubin) were compared for previously fractured and contralateral, uninjured ankles from the same patient. Analysis was also performed to determine the effect of the number of fracture lines and involvement of soft tissue on SF composition.

Interleukin (IL)-6, IL-8, MMP-1, MMP-2, and MMP-3 were significantly elevated in the SF from healed ankles compared to matched contralateral uninjured ankles at approximately 6 months after fracture. There were no differences in markers of cartilage catabolism or hemarthrosis. Only IL-1α was affected by the number of fracture lines while differences were not detected for other analytes or with respect to the involvment of soft tissue.

Sustained intra-articular inflammation, even after complete bone healing, was suggested by elevations of pro-inflammatory cytokines (IL-6 and IL-8). In addition, elevated concentrations of MMPs were also noted and were consistent with a persistent inflammatory environment. This study suggests new evidence of persistent intra-articular inflammation after intra-articular ankle fracture healing and suggests potential mediators for PTOA development.

This work may be relevant to the clinical diagnosis and treatment of post-traumatic osteoarthritis.

The purpose of this study was to evaluate the clinical and radiologic outcomes of patients younger than 20 years, treated with the arthroscopic-talus autologous matrix-induced chondrogenesis (AT-AMIC) technique and autologous bone graft for osteochondral lesion of the talus (OLT).

Eleven patients under 20 years (range 13.3-20.0) underwent the AT-AMIC procedure and autologous bone graft for OLTs. Patients were evaluated preoperatively (T₀) and at 6 (T₁), 12 (T₂), and 24 (T₃) months postoperatively, using the American Orthopaedic Foot & Ankle Society Ankle and Hindfoot (AOFAS) score, the visual analog scale and the SF-12 respectively in its Mental and Physical Component Scores. Radiologic assessment included computed tomographic (CT) scan, magnetic resonance imaging (MRI) and intraoperative measurement of the lesion. A multivariate statistical analysis was performed.

Mean lesion size measured during surgery was 1.1 cm³ ± 0.5 cm³. We found a significant difference in clinical and radiologic parameters with analysis of variance for repeated measures (P < .001). All clinical scores significantly improved (P < .05) from T₀ to T₃. Lesion area significantly reduced from 119.1 ± 29.1 mm² preoperatively to 77.9 ± 15.8 mm² (P < .05) at final follow-up as assessed by CT, and from 132.2 ± 31.3 mm² to 85.3 ± 14.5 mm² (P < .05) as assessed by MRI. Moreover, we noted an important correlation between intraoperative size of the lesion and body mass index (BMI) (P = .011).

The technique can be considered safe and effective with early good results in young patients. Moreover, we demonstrated a significant correlation between BMI and lesion size and a significant impact of OLTs on quality of life.

Level IV, retrospective case series.

Risk factors associated with short-term functional outcomes in patients with operative ankle fractures have been established. However, no previous studies have reported the association between these risk factors and functional outcomes outside of the first postoperative year. We identified predictors of functional and pain outcomes in patients with operative ankle fractures using the Patient Reported Outcomes Measurement System (PROMIS) physical function (PF) and pain interference (PI) measures.

We retrospectively reviewed a multicenter cohort of patients ≥18 years old who underwent operative management of closed ankle fractures from 2001 to 2013 with a minimum of a 2-year follow-up. Patients with pilon variants, Maisonneuve fractures, Charcot arthropathy, prior ankle surgery, and chronic ankle fractures were excluded. Patients meeting inclusion criteria were contacted and evaluated using the PROMIS PF and PI computerized adaptive tests. Patient demographic and injury characteristics were obtained through a retrospective chart review. Univariate and multivariate regression models were developed to determine independent predictors of physical function and pain at follow-up. Included in this study were 142 patients (64 women, 78 men) with a mean age of 52.7 years (SD = 14.7) averaging 6.3 years of follow-up (range 2-14).

Patients had a mean PF of 51.9 (SD = 10.0) and a mean PI of 47.8 (SD = 8.45). Multivariate analysis demonstrated that independent predictors of decreased PF included higher age (B = 0.16, P = .03), higher American Society of Anesthesiologists (ASA) class (B = 10.3, P < .01), and higher body mass index (BMI; B = 0.44, P < .01). Predictors of increased PI included higher ASA class (B = 11.5, P < .01) and lower BMI (B = 0.41, P < .01).

At follow-up, increased ASA class, increased BMI, and higher age at time of surgery were independently predictive of decreased physical function. Factors that were associated with increased pain at follow-up include lower BMI and higher ASA class. ASA class had the strongest effect on both physical function and pain.

Level IV, case series.

Arthroscopic criteria for identifying syndesmotic disruption have been variable and subjective. We aimed to quantify syndesmotic disruption arthroscopically using a standardized measurement device.

Ten cadaveric lower extremity specimens were tested in intact state and after serial sectioning of the syndesmotic structures (anterior inferior tibiofibular ligament [AiTFL], interosseous ligament [IOL], posterior inferior tibiofibular ligament [PiTFL], deltoid). Diagnostic ankle arthroscopy was performed after each sectioning. Manual external rotational stress was applied across the tibiofibular joint. Custom-manufactured spherical balls of increasing diameter mounted on the end of an arthroscopic probe were inserted into the tibiofibular space to determine the degree of diastasis of the tibiofibular joint under each condition.

A ball 3 mm in diameter reliably indicated a high likelihood of combined disruption of the AiTFL and IOL. Disruption of the AiTFL alone could not be reliably distinguished from the intact state.

Use of a spherical probe placed into the tibiofibular space during manual external rotation of the ankle provided an objective measure of syndesmotic instability. Passage of a 2.5-mm probe indicated some disruption of the syndesmosis, but the test had poor negative predictive value. Passage of a 3.0-mm spherical probe indicated very high likelihood of disruption of both the AiTFL and the IOL.

The findings challenge the previously used but unsupported standard of a 2-mm diastasis of the tibiofibular articulation for diagnosis of subtle syndesmotic instability.

Total ankle arthroplasty (TAA) is a rapidly growing treatment for end-stage ankle arthritis that is generally performed as an inpatient procedure. The feasibility of outpatient total ankle arthroplasty (OTAA) has not been reported in the literature. We sought to establish proof of concept for OTAA by comparing outpatient vs inpatient perioperative complications, postoperative emergency department (ED) visits, readmissions, patient satisfaction, and cost analysis.

From July 2010 to September 2015, a total of 36 patients underwent TAA. Patients with prior ankle replacement, prior ankle infections, neuroarthropathy, or osteonecrosis of the talus were excluded from the study. All patient demographics, tourniquet times, estimated blood loss, comorbidities, concomitant procedures, complications, return ED visits, and readmissions were recorded. Patient satisfaction questionnaires were collected. Twenty-one patients had outpatient surgery and 15 had inpatient surgery. The cohorts were matched demographically.

The average length of stay for the inpatient group was 2.5 days. The overall cost differential between the groups was 13.4%, with the outpatient group being less costly. This correlates to a cost savings of nearly $2500 per case. One patient in the outpatient group had a return ED visit on postoperative day 1 for urinary retention. There were no 30-day readmissions in either group. Seventy-one percent of the outpatient group and 93% of the inpatient group would not change to a different postoperative admission status if they were to have the procedure again.

Our results show that OTAA was a cost-effective and safe alternative with low complication rates and high patient satisfaction. With proper patient selection, OTAA was beneficial to both the patient and the health care system by driving down total cost. It has the capacity to generate substantial savings while providing equal or better value to the patient.

Level III, retrospective comparative study.

For patients with hallux rigidus seeking a motion-sparing procedure, interposition arthroplasty is an alternative to fusion. The purpose of this study was to report patient outcomes after interpositional arthroplasty for hallux rigidus.

All patients undergoing interpositional arthroplasty at our institution from 2001 to 2014 were identified and a retrospective chart review was performed. Follow-up was conducted through a telephone survey to obtain survivorship, satisfaction, and functional scores. Survivorship of the interpositional arthroplasty procedure was defined as no subsequent surgery on the hallux after the index procedure. Patients were excluded for incomplete records. Complications were recorded. From 2001 to 2014, 183 patients were identified. Of these, 14 were excluded for incomplete data, leaving 169 patients. Of these, 133 had an average follow-up of 62.2 months (range, 24.3 months to 151.2 months).

The overall failure rate was 3.8% (5/133). Patient-reported outcome was rated as excellent in 65.4% (87/133) or good in 24.1% (32/133) of patients and fair or poor in 10.5% (14/133) of patients. Of 133 patients, 101 (76%) were able to return to fashionable or regular footwear. The infection rate was 1.5% (2/133). Patient-reported cock-up deformity of the first metatarsophalangeal joint (MTPJ) occurred in 4.5% (6/133) of patients. In addition, 17.3% (23/133) of patients reported metatarsalgia of the second or third MTPJ at the time of final follow-up, and there was no significant difference between interposition types (P = .441).

Interpositional arthroplasty for hallux rigidus was found to have excellent or good results in most patients at a mean follow-up of 62.2 months.

Level IV, retrospective case series.

The development of valgus tibiotalar tilt following hindfoot arthrodesis is rarely discussed in the literature. The purpose of this study was to determine the incidence of valgus tibiotalar tilt and to evaluate if there were any radiographic predictors for the development of valgus tibiotalar tilt.

Patients who underwent hindfoot fusion between January 1, 2004 and December 31, 2013 were identified. Charts were reviewed for demographic information and operative details. Preoperative and postoperative radiographs were reviewed for the development of tibiotalar tilt, and standardized measurements and angles were calculated. A total of 187 patients were included. There were 106 (56.7%) females and 81 (43.3%) males. The average age was 52 years (range, 11-82 years). The most common indication for surgery was adult-acquired flatfoot deformity (n = 92, 49.2%), followed by arthritis (n = 83, 44.4%). The most common procedure was triple arthrodesis (n = 101, 54%). Twenty-seven patients demonstrated tibiotalar tilt preoperatively.

A total of 51 patients (27.3%) developed valgus tibiotalar tilt postoperatively at an average of 3.6 months after surgery. We found that an increase in the preoperative Meary (lateral talar–first metatarsal) angle (hazard ratio, 1.039; 95% confidence interval, 1.002-1.077; P < .05) was associated with the development of tibiotalar tilt. An increase in the postoperative Meary angle (hazard ratio, 1.052; 95% confidence interval, 0.999-1.108; P = .0528) approached significance for the development of tibiotalar tilt.

The development of valgus tibiotalar tilt following hindfoot fusion was a notable phenomenon, occurring in 27% of our patient population. The preoperative Meary angle was the only radiographic measurement that was significantly associated with the development of valgus tibiotalar tilt, although the postoperative Meary angle approached significance. These findings should encourage surgeons to be aware of patients with large deformities and of their propensity to develop a valgus deformity about the ankle.

Level III, retrospective comparative series.

Depending on the direction of the subtalar joint, a foot deformity generally tends towards pronation (pes planovalgus) or supination (pes cavovarus). However, the combination of hindfoot varus and flat midfoot/forefoot (pes planovarus) is an exception to this rule. Pes planovarus has so far only been referred to in connection with Müller-Weiss disease and congenital disease. We diagnosed pes planovarus in otherwise healthy patients without these diseases.

Forty patients with 54 symptomatic feet who were treated between August 2012 and July 2016 were included (mean age, 44.1 ± 15.7 years; 15 male/25 female). They were selected from 1064 consecutive cases (3.8%). Inclusion criteria were hindfoot varus and flat midfoot/forefoot. Their symptoms, radiographs, and therapies within the first 3 months were retrospectively analyzed. The position in the hindfoot alignment view (HAV), talometatarsal-1 angle lateral (TMT1lat) and dorsoplantar (TMT1dp), talocalcaneal angle lateral (TCAlat) and dorsoplantar (TCAdp), and calcaneal pitch angle (CPA) were measured on a DICOM/PACS system.

The mean radiological results (standard values from the literature in brackets) were as follows: the hindfoot was significantly in varus in the HAV (−6.9 ± 3.6 mm [−1.6 ± 7.2 mm]; P < .001), the TMT1lat was significantly flatter (−6.7 ± 5.8 degrees [8.4 ± 5.9 degrees]; P < .001), the TMT1dp was significantly less in abduction (1.5 ± 7.9 degrees [7.7 ± 8.2 degrees]; P = .005), the TCAdp showed no difference (25.9 ± 7.9 degrees [24.1 ± 5.7 degrees]; P = .118), the TCAlat was significantly larger (47.5 ± 6.1 degrees [43.4 ± 7.1 degrees]; P < .001), and the CPA was significantly flatter (17.6 ± 3.9 degrees [24.5 ± 3.0 degrees]; P < .001). The most frequent symptoms were stress-induced foot pain (n = 33), hallux valgus (n = 20), chronic ankle instability (n = 17), metatarsalgia (n = 15), chronic midfoot pain (n = 13), heel pain (n = 12), and lesser toe deformities (n = 8). Thirty-one feet were treated conservatively and 23 operatively.

This study showed the existence of pes planovarus without Müller-Weiss disease or congenital disease. This unusual foot form leads to difficulties if standard treatment strategies are applied, which raises the issue of the correct treatment for such patients.

Level IV, retrospective case series.

Taping is an effective temporary therapy for improving hallux valgus (HV) in adults. Although HV has been demonstrated to impair postural balance, there is a lack of information about how corrective taping affects balance and gait patterns in adults with HV deformity.

Eighteen middle-aged female patients (average age, 53.5 years) with HV were included. Corrective tape was applied to correct HV angulation. A series of balance and gait stability tests were performed before applying tape and 1 hour after the tape was applied with a Balance Master computerized posturography device. The study involved the following tests: modified clinical test of sensory interaction and balance (mCTSIB), unilateral stance (US), limit of stability (LoS), step up/over (SUO), and walk across (WA) tests.

No significant difference was found between the no-tape and taped condition in the static balance mCTSIB and US tests (P > .05). The taping intervention resulted in significant improvement in the dynamic balance measures for the LoS test’s backward reaction time and left maximum excursion (P < .05), a significantly higher impact index bilaterally in the SUO assessment (P < .05), and an increase in step width mean and variability in the WA test (P < .05).

Taping for correcting HV angulation had negative acute effects on dynamic balance in the SUO and WA tests and positive effects in the LoS test.

Corrective taping, although a form of conservative treatment for hallux valgus, has been insufficiently studied in terms of effects on balance. Our results show that taping, as an acute effect, may impair balance in middle-aged adults when walking or ascending and descending stairs.

Hallux rigidus can be treated using several different methods and the best treatment option depends on the severity of degenerative changes of the metatarsophalangeal (MTP) joint. However, the ideal operative option for advanced hallux rigidus remains debatable. This prospective study was performed to evaluate the intermediate-term clinical outcomes of distal metatarsal osteotomy used as a joint-preserving method for the treatment of advanced hallux rigidus.

Forty-two cases (39 patients) were followed for more than 3 years after distal metatarsal dorsiflexion osteotomy for advanced hallux rigidus of grade III-IV. Clinical evaluations included the American Orthopaedic Foot & Ankle Society (AOFAS) scores, Foot and Ankle Ability Measure (FAAM) scores, and patient subjective satisfaction scores. Range of motion (ROM) of great toe, complications, reoperation rates, width of the MTP joint space, and times to union were evaluated.

Mean AOFAS hallux and mean FAAM scores significantly improved from 56.4 and 61.2 points preoperatively to 87.6 and 88.7 points at final follow-up, respectively (P < .001). Grade III and IV groups had significantly different AOFAS and FAAM scores at final follow-up. Mean dorsiflexion of great toe significantly improved from 14.8° preoperatively to 35.5° at final follow-up (P < .001). Mean patient satisfaction score at final follow-up was 92.8 points. There were 4 cases (9.5%) of subsequent fusion and 2 cases (4.8%) of transfer metatarsalgia.

Distal metatarsal dorsiflexion osteotomy using bio-compression screws appears to be an effective operative option for grade III advanced hallux rigidus with viable cartilage on >50% of the first metatarsal articular surface, as it restored joint motion, provided reliable pain relief, and did not require implant removal. However, based on the unsatisfactory clinical results and the high rate of reoperation observed, the authors cannot recommend this operative method for the treatment of end-stage (grade IV) hallux rigidus.

Level IV, prospective case series.

The American Orthopaedic Foot & Ankle Society (AOFAS) score is one of the most common and adapted outcome scales in hallux valgus surgery. However, AOFAS is predominantly physician based and not patient based. Although it may be straightforward to derive statistical significance, it may not equate to the true subjective benefit of the patient’s experience. There is a paucity of literature defining MCID for AOFAS in hallux valgus surgery although it could have a great impact on the accuracy of analyzing surgical outcomes. Hence, the primary aim of this study was to define the Minimal Clinically Important Difference (MCID) for the AOFAS score in these patients, and the secondary aim was to correlate patients’ demographics to the MCID.

We conducted a retrospective cross-sectional study. A total of 446 patients were reviewed preoperatively and followed up for 2 years. An anchor question was asked 2 years postoperation: “How would you rate the overall results of your treatment for your foot and ankle condition?” (excellent, very good, good, fair, poor, terrible). The MCID was derived using 4 methods, 3 from an anchor-based approach and 1 from a distribution-based approach. Anchor-based approaches were (1) mean difference in 2-year AOFAS scores of patients who answered “good” versus “fair” based on the anchor question; (2) mean change of AOFAS score preoperatively and at 2-year follow-up in patients who answered good; (3) receiver operating characteristic (ROC) curves method, where the area under the curve (AUC) represented the likelihood that the scoring system would accurately discriminate these 2 groups of patients. The distribution-based approach used to calculate MCID was the effect size method. There were 405 (90.8%) females and 41 (9.2%) males. Mean age was 51.2 (standard deviation [SD] = 13) years, mean preoperative BMI was 24.2 (SD = 4.1).

Mean preoperative AOFAS score was 55.6 (SD = 16.8), with significant improvement to 85.7 (SD = 14.4) in 2 years (P value < .001). There were no statistical differences between demographics or preoperative AOFAS scores of patients with good versus fair satisfaction levels. At 2 years, patients who had good satisfaction had higher AOFAS scores than fair satisfaction (83.9 vs 78.1, P < .001) and higher mean change (30.2 vs 22.3, P = .015). Mean change in AOFAS score in patients with good satisfaction was 30.2 (SD = 19.8). Mean difference in good versus fair satisfaction was 7.9. Using ROC analysis, the cut-off point is 29.0, with an area under the curve (AUC) of 0.62. Effect size method derived an MCID of 8.4 with a moderate effect size of 0.5. Multiple linear regression demonstrated increasing age (β = −0.129, CI = −0.245, –0.013, P = .030) and higher preoperative AOFAS score (β = −0.874, CI = −0.644, –0.081, P < .001) to significantly decrease the amount of change in the AOFAS score.

The MCID of AOFAS score in hallux valgus surgery was 7.9 to 30.2. The MCID can ensure clinical improvement from a patient’s perspective and also aid in interpreting results from clinical trials and other studies.

Level III, retrospective comparative series.

National orthopaedic meetings are used to disseminate current research through podium and poster abstract presentations. Not all of these abstracts go on to full-text journal publication. The purpose of this study was to determine the publication rates of podium and poster presentations from the American Orthopaedic Foot & Ankle Society (AOFAS) annual meetings between 2008 and 2012.

All accepted podium and poster abstracts from the 2008-2012 AOFAS annual meetings were compiled from the AOFAS office, Physician Resource Center website, and hardcopy meeting programs. PubMed and Google Scholar searches were performed for journal publications using key words in the presentation abstracts and authors’ names. Full-text journal publication rates for the presentations were calculated per year, as were the most common journals of publication.

Overall full-text publication rate was 73.7% for podium presentations and 55.8% for posters. Podium presentations were published in a journal significantly more often than posters (P < .0001; odds ratio 2.17 [95% confidence interval (CI), 1.64-2.86]). The mean time to publication was 1.5 and 1.4 years for podium and poster presentations, respectively (P = .124). The most common journal for podium and poster publications was Foot & Ankle International.

Podium abstracts were significantly more likely to be published compared to posters. The AOFAS overall full-text journal publication rate was one of the higher reported rates compared with other national orthopedic society meetings, which have ranged from 34% to 73%.

Controversy exists regarding the ideal Achilles rupture treatment; however, operative treatment is considered for athletes and active patients. The ideal repair construct is evolving, and the effect of suture caliber or number of core strands has not been studied.

Simulated mid-substance Achilles ruptures were performed in 24 cadavers. Specimens were randomized to three 6-core-strand style repair constructs: (1) 4 No. 2 sutures and two 2-mm tapes (2T); (2) 2 No. 2 sutures and four 2-mm tapes (4T); (3) 12 (double-6-strand) strand repair (12 No. 2-0 sutures [12S]). Repairs were subjected to a cyclic loading protocol representative of postoperative rehabilitation. These data were compared to a previously published standard open repair technique (6-core strands with No. 2 sutures) on 9 specimens tested under the same conditions.⁶

No significant elongation differences were observed between the repair groups and the previously published standard repair group in the first 2 stages of the simulated rehabilitation protocol. Both the 2T and 12S repairs survived a significantly greater number of cycles to failure (P = 0.0005, P = 0.0267, respectively) and had a significantly higher failure load (P = .0005, P = .0118, respectively) compared to the previously published data. These 2 constructs consistently survived the advanced stages of the simulated rehabilitation protocol. The majority of repairs failed at the knots.

In this study, the 2T and 12S constructs survived the later stages of our simulated rehabilitation protocol, suggesting that they may be able to accommodate a more aggressive clinical rehabilitation protocol. Substituting suture-tape for 2 core strands or doubling the core strands with a smaller-caliber suture created a biomechanically stronger construct.

Achilles repair with an added nonabsorbable, high–tensile strength tape allowed for a stronger construct that may allow for a more aggressive, early rehabilitation protocol and earlier return to function.

Although retrograde intramedullary nails for tibiotalocalcaneal arthrodesis (TTCA) are an established fixation method, few studies have evaluated the stability of the available nail systems. The purpose of this study was to compare biomechanically the primary stability of 2 nail-systems, A3 (Small Bone Innovations) and HAN (Synthes), in human cadavers and analyze the exact point of instability in TTCA by means of optical measurement.

In 6 pairs of lower legs (n = 12) of fresh-frozen human cadavers with osteoporotic bone structure, bone mineral density (BMD) was determined. Pairwise randomized implantation of either an HAN or A3 nail was executed. Performance and stability were measured by quasi-static tests using 3D motion tracking (NDI Optotrak-Certus) followed by cyclic loading tests during dorsi- and plantarflexion.

3D optical analysis in quasi-static tests showed a significantly lower degree of movement for the HAN nail in rotational and dorsi-/plantarflexion, especially in the subtalar joint. Cyclic loading tests were consistent with quasi-static tests.

The A3 nail offered lower stability during axial torsion in the ankle and subtalar joints and during plantar- and dorsiflexion in the subtalar joint in osteoporotic bones. This study was the first to examine the primary stability of different arthrodesis nails in TTCA and their bony parts with a 3D motion analysis.

The better stability of the locking-only HAN nail in this osteoporotic test setup could lead to more favorable results in comparison to the A3 nail in clinical use.