Tibiotalocalcaneal arthrodesis: a biomechanical comparision of multiplanar external fixation with intramedullary fixation

Subtalar joint involvement with tibiotalocalcaneal intramedullary nail arthrodesis

Tibiotalocalcaneal (TTC) fusion with an intramedullary nail (IMN) has been utilized for a myriad of indications in hindfoot and ankle reconstruction. However, some controversies remain on the optimal position of the hindfoot. Previous studies have reported on the potential medialization of the rearfoot during insertion of the IMN, but few studies have examined the potential affect on the subtalar joint. We performed the present cadaveric study in order to assess the involvement of a 12-mm IMN with the posterior facet of the calcaneus. A 3-mm guide wire (for a standard TTC IMN) was inserted in an anterograde fashion beginning within the central aspect of the tibial canal in 10 fresh-frozen below knee cadaver specimens. The subtalar joint of each specimen was exposed and images of the posterior facet were collected. Utilizing an open source Java image processing program (ImageJ/Fiji), we calculated a mean native calcaneal posterior facet of 4.6 cm2 with a post ream surface area of 3.6 cm2, resulting in a mean of 21.4% of the posterior facet occupied by an IMN in an anterograde fashion. In conclusion, a TTC IMN placed in optimal position within the ankle and tibia is likely to occupy, on average, a fifth of the calcaneal posterior facet. Though this does leave some possibility of a medial shift of the rearfoot complex, care must be taken to not violate the lateral calcaneal or talar wall.

A Single-Center Comparative Study: Outcome Analysis of Fixation Techniques for Tibiotalocalcaneal Arthrodesis

Introduction Tibiotalocalcaneal arthrodesis (TTCA) is a well-known and accepted surgical technique for end-stage ankle osteoarthritis. The aim of this study is to compare the postoperative clinical and radiological comparison of retrograde intramedullary nailing (RIMN) and plate/cannulated screw (P/cS) fixation methods in patients undergoing TTCA. Methods Patients with end-stage ankle osteoarthritis due to traumatic causes or rheumatic diseases between December 2012 and March 2019 were included in the retrospective study. Patients who underwent isolated tibiotalar or isolated subtalar arthrodesis were not included in the study. Functional scores of patients with bone fusion were evaluated using the American Orthopaedic Foot and Ankle Society (AOFAS) and Short Form-36 (SF-36) quality of life score surveys, administered either in person or by phone. From the radiological point of view, it was evaluated whether the union was achieved with the two-view ankle radiograph. There were 48 patients who underwent ankle arthrodesis in the clinical archive. A total of 31 patients were excluded from the study due to failure to attend follow-up, inability to be reached, or non-compliance with study criteria. The mean age of the patients participating in the study was 44.12 ± 12.95 years, the follow-up time was 40.06 ± 27.31 months, the union time was 5.19 ± 3.17 months, and the AOFAS score was 53.12 ± 13.87. SF-36 scores were evaluated among their own subunits. Results A total of 17 patients were enrolled in the study, of whom 13 were male (76.47%) and 4 were female (23.53%). There was no significant effect of the fixation methods (RIMN or P/cS) selected for TTCA on union times (p>0.05). However, there were significant differences in some parameters of the SF-36 when compared by gender. According to this, the scores of men in physical function (PF), mental health (MH), and general health perception (GHP) were higher than those of women. When AOFAS and SF-36 scores were compared by fixation type, no statistically significant difference was found (p>0.05). Conclusion This study investigated the impact of the fixation method on clinical and radiological outcomes in TTCA. We found that both methods were clinically similar in terms of bone union time and surgical efficacy. However, men had better physical function, mental health, and general health perception after TTCA than women.

Tibiotalocalcaneal Arthrodesis in Severe Hindfoot Deformities

Tibiotalocalcaneal arthrodesis (TTCA) is the most common and reliable procedure in the treatment of patients with end-stage ankle arthritis combined with severe deformity. Many of these patients present with difficult previous sequelae that include nonunion, malunion, broken implants, vascular deficiencies, skin problems, or a combination of the previous. In that complex scenario, sometimes the only alternative treatment is a below-the-knee amputation. Image studies--weightbearing X-rays, tomography, and magnetic resonance - are fundamental to evaluate alignment and bone stock. When all conservative treatments fail to alleviate pain and dysfunction, the combination of osteotomies and arthrodesis is the procedure of choice. Surgical planning needs to be very detailed and thorough with a special focus on bone loss after debridement of non-healthy tissue and removal of metalwork. TTCA with grafting allows for the preservation of the limb in more than 80% of cases but at the expense of many complications with nonunion rates of approximately 20% of cases. There is controversy about the use of a retrograde nail versus specific TTCA plate and screws but results from biomechanical studies do not show a clear superiority of one specific construct. Amputation rates are close to 5% of cases after repeated failed surgeries. Bulk allografts increase the rate of nonunions but apparently do not have an influence on postoperative infections. Valgus positioning of the ankle/hindfoot is paramount to allow for maximal sagittal plane compensation from the midtarsal joints. Most patients are satisfied with the results of these salvage operations. The studies presented in this article have a considerable wide array of different scenarios that obviously bias some of the results, complications, and outcomes but together they present a persuasive pattern toward considering TTC with grafting and nail or plate fixation as a good salvage procedure that may help the patients to maintain their foot and ankle with a better alignment, function, and pain relief.

Tibiotalocalcaneal Arthrodesis With the Hindfoot Arthrodesis Nail: A Prospective Consecutive Series From a Single Institution

Tibiotalocalcaneal arthrodesis (TTCA) is a salvage procedure. We report a series of 20 patients who underwent TTCA using an intramedullary nail. Of the 20 patients, 7 (35%) had diabetes mellitus. The patient experiences and outcomes were analyzed. Their mean age was 61.1 (range 39 to 78) years. The minimum follow-up period was 13 (mean 28, range 13 to 49) months. Surgical indications included diabetic Charcot arthropathy in 7 (35%), hindfoot osteoarthritis in 10 (50%), and severe equinovarus deformity in 3 (15%). A calcaneal spiral blade was used in 2 patients (10%). Significant improvements (p < .05) were observed in 5 of 8 Short-Form 36-item Health Survey components, the American Orthopaedic Foot and Ankle Society Ankle-Hindfoot scale (p < .001), and visual analog scale for pain (p < .001). The mean length of the hospital stay was 6.7 (range 1 to 27) days. Of the 20 patients, 76.9% had improvement in their activity postoperatively. Also, 81.8% were able to resume their preoperative work after a mean of 7.89 (range 3 to 24) months. Overall, 19 patients (95%) reported favorable outcomes. Superficial wound infection (n = 4; 20%) and deep wound infection (n = 3; 15%) were the most common complications (35%), with 1 case (5%) culminating in a below-the-knee amputation. Radiographic union was achieved in 16 of the tibiotalar joints (80%), 16 subtalar joints (80%), and 4 tibiocalcaneal fusions (20%). In a subgroup analysis of 7 patients with diabetes mellitus (35%), the incidence of wound complications and fusion was comparable to that of the primary cohort. TTCA performed with an intramedullary nail appears to offer a reliable and safe alternative for patients with severe ankle and hindfoot pathologic entities, including those with diabetes mellitus.

Tibio-talo-calcaneal fusion after limb salvage procedures-A retrospective study

BACKGROUND

The treatment of limb threatening trauma on the distal tibia or hindfoot often results in posttraumatic osteoarthritis requiring tibiotalocalcaneal (TTC) arthrodesis. The purpose of this study was to present a case series of patients undergoing various techniques of joint fusion after bone reconstruction and deformity correction as a salvage procedure. The study should help trauma surgeons making decisions in limb salvage and deformity correction in complex lower leg and foot injuries by presenting options and treatment strategies.

PATIENTS AND METHODS

Eight patients (4 male, 4 female) after TTC arthrodesis as a definitive procedure after polytrauma or monotrauma involving the distal tibia or hindfoot were the subject of this retrospective analysis. We included patients treated by external ring fixation (1 case), external fixation+wires (1 case), external fixation+screws (1 case) and intramedullary nailing (1 ante- and 5 retrograde; 1 bilateral, 4 unilateral). Initial trauma included open fractures, subtotal foot amputations and closed fractures with failed osteosynthesis and failed ankle joint replacement. Bone defects were treated with callus distraction or segment transport in 5 cases. Various angles were measured to assess foot deformities in the lateral radiographic view and clinical results were presented.

RESULTS

Independent, pain-free mobilisation with full weight bearing was achieved in all 8 patients. In terms of subjective outcome, all patients reported a highly satisfying result. Complete consolidation at the fusion site was achieved in 8 out of 9 cases with a high rate of adjacent joint arthritis. Angles measures in the lateral radiographs showed values typical for a pes cavus tendency.

CONCLUSION

Tibio-talo-calcaneal (TTC) arthrodesis is a viable treatment option for severe post traumatic arthritis and deformity of the ankle and subtalar joint. Despite bad bone quality retrograde intramedullary nailing does provide acceptable results providing stability, low invasiveness and low infection rate. Simultaneous TTC-fusion and tibial lengthening using the Ilizarov ring fixator may be necessary when the surgeon is confronted with large bone defects - often followed by a nailing after lengthening procedure. This study shows that limb preservation after limb threatening trauma with hindfoot injury and multiple fractures of the lower extremity is recommenced as the method of choice with reasonable clinical results.

LEVEL OF EVIDENCE

IV, Case series.

Measurement of Nitinol Recovery Distance Using Pseudoelastic Intramedullary Nails for Tibiotalocalcaneal Arthrodesis

BACKGROUND

Tibiotalocalcaneal arthrodesis is a salvage procedure for patients with complex disease of the ankle and subtalar joints. Despite the clinical efficacy and mechanical advantage of intramedullary nails, complications, such as nonunion, are common. It may be possible to sustain compression in the face of bone resorption and implant loosening over the course of healing using a novel pseudoelastic intramedullary nail with an internal nitinol element.

METHODS

We identified 15 patients with average age of 54.7 years (range, 28-75 years) who had undergone a tibiotalocalcaneal arthrodesis using a pseudoelastic intramedullary nail. Serial radiographs were used to determine the amount and rate of nitinol element migration over the first 3 postoperative months.

RESULTS

Postoperatively, there was at least 2.38 mm of nitinol element migration proximally with mean of 5.58 mm (± 1.38), (range, 2.38-8.11 mm). Average follow-up time was 195 days (± 106.3), (range, 89-490 days). On average, 86% of the total recovered distance took place within the first 39.7 days (±10.03).

CONCLUSIONS

The nitinol element recovers distance when stretched intraoperatively and maintains moderate compression in response to bone resorption. Further studies are needed to assess if this increased compression lends itself to higher fusion rates than traditional intramedullary nails.

LEVELS OF EVIDENCE

Therapeutic, Level IV: Case series.

A modified and enhanced test setup for biomechanical investigations of the hindfoot, for example in tibiotalocalcaneal arthrodesis

Background

Tibiotalocalcaneal arthrodesis (TTCA) using intramedullary nails is a salvage procedure for many diseases in the ankle and subtalar joint. Despite “newly described intramedullary nails” with specific anatomical shapes there still remain major complications regarding this procedure. The following study presents a modified biomechanical test setup for investigations of the hindfoot.

Methods

Nine fresh-frozen specimens from below the human knee were anaysed using the Hindfoot Arthrodesis Nail (Synthes) instrument. Quasi-static biomechanical testing was performed for internal/external rotation, varus/valgus and dorsal/plantar flexion using a modified established setup (physiological load entrance point, sledge at lever arm to apply pure moments). Additionally, a 3D optical measurement system was added to allow determination of interbony movements.

Results

The mean torsional range of motion (ROM) calculated from the actuator data of a material testing machine was 10.12° (SD 0.6) compared to 10° (SD 2.83) as measured with the Optotrak® system (between tibia and calcaneus). The Optotrak showed 40 % more rotation in the talocrural joint.

Mean varus/valgus ROM from the material testing flexion machine was seen to be 5.65° (SD 1.84) in comparison to 2.82° (SD 0.46) measured with the Optotrak. The subtalar joint showed a 70 % higher movement when compared to the talocrural joint.

Mean ROM in the flexion test was 5.3° (SD 1.45) for the material testing machine and 2.1° (SD 0.39) for the Optotrak. The movement in the talocrural joint was 3 times higher compared to the subtalar joint.

Conclusion

The modified test setup presented here for the hindfoot allows a physiological biomechanical loading. Moreover, a detailed characterisation of the bone-implant constructs is possible.

Tibiotalocalcaneal arthrodesis using a retrograde intramedullary nail with a valgus curve

OBJECTIVE

Many different techniques have been described for performing tibiotalocalcaneal arthrodesis (TTCA) in patients with severe hindfoot disorders such as failed ankle arthroplasty and failed ankle joint arthrodesis with subsequent subtalar arthritis. The use of straight retrograde intramedullary nails is extremely limited because they may interfere with normal heel valgus position and risk damaging the lateral plantar neurovascular structures. Curved retrograde intramedullary nails have been designed to overcome these shortcomings. The purpose of this single surgeon series was to investigate the outcomes of TTCA using a curved retrograde intramedullary nail.

METHODS

From June 2009 to January 2012, 22 patients underwent TTCA using intramedullary nails with a valgus curve by the same senior surgeon. All patients were available for analysis, the mean follow-up being 22.3 months (range, 6.8-38 months). The main outcome measurements included EQ-5D functional scores, the American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot scale, radiologic assessment and clinical examination.

RESULTS

Bony union and a plantigrade foot were achieved in 100% of subjects, the mean time to union being 3.9 months (range, 2.4 to 6.2 months). Structural bone graft was used in all patients. Postoperative radiologic results showed a good hindfoot alignment in all patients. The only complication was one case of delayed wound healing without deep infection. The mean postoperative EQ-5D functional and AOFAS ankle-hindfoot scores were 69.33 (range, 20 to 90) and 69.9 (range, 45 to 85) points, respectively. No revision surgery was necessary in our cohort.

CONCLUSION

The results of the present study indicate that TTCA using a short, retrograde, curved intramedullary nail is an acceptable technique for obtaining solid fusion and good hindfoot alignment inpatients with severe hindfoot disorders.

Tibiotalocalcaneal arthrodesis with retrograde intramedullary nailing: 29 patients' clinical and functional evaluation

Objective

To evaluate clinically and functionally the pos-operative results of patients submitted to tibiotalocalcaneal arthrodesis for the treatment of traumatic arthropathy and neuropathy.

Methods

Retrospective study of 29 patients undergoing ankle arthrodesis with intramedullary retrograde nail. All patients were evaluated for fusion time, AOFAS and VAS scores, satisfaction, and complications of surgery. The mean follow-up was 36 months (range 6–60 months).

Results

The union rate was 82%, and the consolidation occurred on average at 16 weeks (10–24 weeks). The pos-operative AOFAS score improved in 65.5% (average of 57.7 on neurological cases and 75.7 on cases pos-traumatic) and VAS score improved 94.1% (average of 2.3 on neurological cases and 4,2 on post-traumatic cases), and 86% of patients were satisfied with the procedure performed. Complications occurred in 11 patients (38%), including pseudoarthrosis (17.24%), infection (17.24%), material failure (13.8%) and fracture (13.8%).

Conclusion

Tibiotalocalcaneal arthrodesis with retrograde intramedullary nail proved to be a good option for saving the ankle joint, with improvement of clinical and functional scores (AOFAS = 65.5% and VAS = 94.1%).

Primary stability and stiffness in ankle arthrodes-crossed screws versus anterior plating

BACKGROUND

Ankle arthrodesis is commonly used for the treatment of osteoarthritis or failed arthroplasty. Screw fixation is the predominant technique to perform ankle arthrodesis. Due to a considerable frequency of failures research suggests the use of an anatomically shaped anterior double plate system as a reliable method for isolated tibiotalar arthrodesis. The purpose of the present biomechanical study was to compare two groups of ankle fusion constructs - three screw fixation and an anterior double plate system - in terms of primary stability and stiffness.

METHODS

Six matched-pairs human cadaveric lower legs (Thiel fixated) were used in this study. One specimen from each pair was randomly assigned to be stabilized with the anterior double plate system and the other with the three-screw technique. The different arthrodesis methods were tested by dorsiflexing the foot until failure of the system, defined as rotation of the talus relative to the tibia in the sagittal plane. Experiments were performed on a universal materials testing machine. The force required to make arthrodesis fail was documented. For calculation of the stiffness, a linear regression was fitted to the force-displacement curve in the linear portion of the curve and its slope taken as the stiffness.

RESULTS

For the anatomically shaped double-plate system a mean load of 967N was needed (range from 570N to 1400N) to make arthrodesis fail. The three-screw fixation method resisted a mean load of 190N (range from 100N to 280N) (p=0.005). In terms of stiffness a mean of 56N/mm (range from 35N/mm to 79N/mm) was achieved for the anatomically shaped double-plate system whereas a mean of 10N/mm (range from 6N/mm to 18N/mm) was achieved for the three-screw fixation method (p=0.004).

CONCLUSIONS

Our biomechanical data demonstrates that the anterior double-plate system is significantly superior to the three-screw fixation technique for ankle arthrodesis in terms of primary stability and stiffness.

Tibiotalocalcaneal arthrodesis with bulk femoral head allograft for salvage of large defects in the ankle

BACKGROUND

Tibiotalocalcaneal arthrodesis in patients with large segmental bony defects presents a substantial challenge to successful reconstruction. These defects typically occur following failed total ankle replacement, avascular necrosis of the talus, trauma, osteomyelitis, Charcot, or failed reconstructive surgery. This study examined the outcomes of tibiotalocalcaneal (TTC) arthrodesis using bulk femoral head allograft to fill this defect.

METHODS

Thirty-two patients underwent TTC arthrodesis with bulk femoral head allograft. Patients who demonstrated radiographic union were contacted for SF-12 clinical scoring and repeat radiographs. Patients with asymptomatic nonunions were also contacted for SF-12 scoring alone. Preoperative, intraoperative, and postoperative factors were analyzed to determine positive predictors for successful fusion.

RESULTS

Sixteen patients healed their fusion (50% fusion rate). Diabetes mellitus was found to be the only predictive factor of outcome; all 9 patients with diabetes developed a nonunion. In this series, 19% of the patients went on to require a below-knee amputation.

CONCLUSIONS

Although the radiographic fusion rate was low, when the 7 patients who had an asymptomatic nonunion were combined with the radiographic union group, the overall rate of functional limb salvage rose to 71%. TTC arthrodesis using femoral head allograft should be considered a salvage procedure that is technically difficult and carries a high risk for complications. Patients with diabetes mellitus are at an especially high risk for nonunion.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Arthroscopic tibiotalocalcaneal arthrodesis with locked retrograde compression nail

Tibiotalocalcaneal (TTC) arthrodesis is a demanding procedure. Several techniques have been described for successful fusion, including the use of plates, screws, intramedullary nails, and external fixators. Arthroscopic TTC fusion with intramedullary nailing has been recently described as an alternative method to traditional open procedures. The surgical technique and clinical and radiographic outcomes of 2 patients who had undergone arthroscopic TTC arthrodesis with intramedullary nailing are presented. The indication for surgery was symptomatic tibiotalar and subtalar post-traumatic arthritis in 1 patient and distal tibia and fibula nonunion in the other. In both cases, fusion was obtained at approximately 8 weeks postoperatively. At the final follow-up visit at 2 years postoperatively, their American Orthopaedic Foot and Ankle Society score had improved from 31 to 85 points and from 16 to 71 points, respectively. No intra- or postoperative complications developed. Arthroscopic TTC arthrodesis can be an alternative to traditional open procedures, especially in patients with soft tissue concerns or several previous surgeries. Experience with ankle arthroscopy procedures is mandatory to obtain satisfactory results and minimize the risk of complications.

Advances in intramedullary nail fixation in foot and ankle surgery

Tibiotalocalcaneal arthrodesis for the treatment of complex foot and ankle deformities are extremely challenging cases. Technological advances in intramedullary nail fixation have improved the biomechanical properties of available fixation constructs in recent years. Nails designed specifically to accommodate hindfoot anatomy, advancement in the understanding of optimal screw orientation, fixed angle technology, the availability of spiral blade screws, and features designed to achieve compression across the arthrodesis site have provided the foot and ankle surgeon with a greater armamentarium for performing tibiotalocalneal arthrodesis. Although advances may help to improve clinical results, small sample sizes and the low-level evidence of study designs limit the evaluation of how these advances affect clinical outcomes.

The slot graft technique for foot and ankle arthrodesis in a high-risk patient group

BACKGROUND

High rates of arthrodesis nonunion have been described in the ankle, hindfoot and midfoot in patients with significant risk factors. The purpose of this study was to evaluate fusion rates, risk of reoperation, postoperative pain scores and patient satisfaction for a slot graft inlay arthrodesis technique used in a high-risk group of foot and ankle patients.

MATERIALS AND METHODS

We retrospectively reviewed all ankle, hindfoot and midfoot arthrodeses by two foot and ankle surgeons in our institution between January 2000 and January 2009. Seventeen arthrodesis procedures in 16 patients using the slot graft technique were identified. Patient charts were reviewed for medical history, risk factors, previous surgery and postoperative complications. Time to union was evaluated on radiographs. Patients provided final followup by phone with an assessment of pain, overall satisfaction and use of orthotic or assistive devices.

RESULTS

Union occurred in 13 arthrodesis procedures (77%) with an average time to union of 5 months. Postoperative infection occurred in one patient. Additional surgery was performed in nine patients. At final followup patients reported low pain scores (3 of 10) and high satisfaction (8 of 10). Fourteen of 15 patients contacted indicated that they would choose to undergo the procedure again.

CONCLUSION

The slot graft arthrodesis technique provided satisfactory results in this small group of patients with a low complication rate. Patient satisfaction rates were high with low pain scores at an average of 62 months postoperatively.

Primary tibiotalocalcaneal arthrodesis

Tibiotalocalcaneal (TTC) arthrodesis is a salvage operation to treat a difficult problem; normal function is not expected with arthrodesis of these 2 major joints. However, in properly selected patients, TTC arthrodesis using intramedullary nailing is an effective technique to reduce pain and improve function. It allows load sharing, provides anatomic alignment, and has the advantage of being able to simultaneously arthrodese both the joints with 1 device. Its use is not without risks, and care must be taken when choosing the insertion site to reduce the risk of neurovascular insult.

Tibiotalocalcaneal arthrodesis with a curved, interlocking, intramedullary nail

BACKGROUND

Tibiotalocalcaneal fusion with a straight rod has a risk of damaging the lateral plantar neurovascular structures and may interfere with maintaining normal heel valgus position.We report the results of a prospective study of tibiotalocalcaneal (TTC) arthrodesis with a short, anatomically curved interlocking, intramedullary nail.

MATERIAL AND METHODS

Forty-five arthrodesis in 42 patients, performed between Jan 2003 and Oct 2008, were prospectively followed. The mean followup was 48 (range, 10 to 74) months. The main indications for the procedure were failed ankle arthrodesis with progressive subtalar arthritis, failed ankle arthroplasty and complex hindfoot deformity. The outcome was measured by a combination of pre and postoperative clinical examination, AOFAS hindfoot scores, SF-12 scores and radiological assessment.

RESULTS

Union rate was 89% (40/45). Eighty-two percent (37/45) reported improvement in pain and 73% (33/45) had improved foot function. Satisfactory hindfoot alignment was achieved in 84% (38/45). Postoperatively there was a mean improvement in the AOFAS score of 37. Complications included a below knee amputation for persistent deep infection, five nonunions, and three delayed unions. Four nails, six proximal and six distal locking screws were removed for various causes. Other complications included two perioperative fractures, four superficial wound infections and one case of lateral plantar nerve irritation.

CONCLUSION

With a short, anatomically curved intramedullary nail, we had a high rate of tibiotalocalcaneal fusion with minimal plantar neurovascular complications. We believe a short, curved intramedullary nail, with its more lateral entry point, helped maintain hindfoot alignment.

Development of a technique for cement augmentation of nailed tibiotalocalcaneal arthrodesis constructs

BACKGROUND

Tibiotalocalcaneal arthrodesis with a retrograde nail is an established procedure. Many patients considered for this arthrodesis have poor bone stock, which may make it difficult to obtain construct stability. This study was undertaken to determine whether stability could be enhanced by the cement augmentation of the calcaneal locking screws.

METHODS

A cannulated and perforated screw, and a technique for cement augmentation via this screw, were developed. Eight pairs of human cadaver bones were instrumented with a retrograde intramedullary device (Expert Hindfoot Arthrodesis Nail, Synthes AG, Solothurn, Switzerland). Within each pair, one specimen was randomized to have the nail interlocked in the calcaneus with two conventional screws; while the other specimen was similarly instrumented with the use of two cement-augmented screws. The bone mineral density was determined. In quasi-static tests, the neutral zone and the range of motion of the constructs were determined. Subsequently the specimens were tested in dorsiflexion/plantar flexion until failure occurred. The neutral zone and the range of motion of the constructs were determined every 200 cycles.

FINDINGS

Augmentation resulted in significantly greater stiffness and a significantly smaller range of motion in the quasi-static dorsiflexion/plantar flexion test, and in a significantly smaller neutral zone in all quasi-static tests. With cyclic loading, the number of cycles to failure was significantly larger in the augmented group. In both groups, bone mineral density was significantly correlated with the number of cycles to failure. Two augmented screws broke.

INTERPRETATION

Cement augmentation confers significant mechanical benefit in hindfoot arthrodesis and therefore can be used as a salvage procedure. Further development should be performed to validate the concept.

Surgery on the rheumatoid ankle joint: efficacy versus effectiveness

This article examines synovectomy and ankle arthrodesis for the rheumatoid ankle joint. Reviews of osteoimmunology and gait analyses specific to rheumatoid arthritis are included. Comparison studies including ankle arthrodesis and total ankle arthroplasty are reviewed.

Comparison of calcaneal fixation of a retrograde intramedullary nail with a fixed-angle spiral blade versus a fixed-angle screw

BACKGROUND

Retrograde intramedullary nailing is an established technique for tibiotalocalcaneal arthrodesis (TTCA). In poor bone stock (osteoporosis, neuroarthropathy), device fixation in the hindfoot remains a problem. Fixed-angle spiral-blade fixation of the nail in the calcaneus could be useful.

MATERIALS AND METHODS

In seven matched pairs of human below-knee specimens, bone mineral density (BMD) was determined, and TTCA was performed with an intramedullary nail (Synthes Hindfoot Arthrodesis Nail HAN Expert Nailing System), using a conventional screw plus a fixed-angle spiral blade versus a conventional screw plus a fixed-angle screw, in the calcaneus. The constructs were subjected to quasi-static loading (dorsiflexion/plantarflexion, varus/valgus, rotation) and to cyclic loading to failure. Parameters studied were construct neutral zone (NZ) and range of motion (ROM), and number of cycles to failure.

RESULTS

With dorsiflexion/plantarflexion loading, the screw-plus-spiral-blade constructs had a significantly smaller ROM in the quasi-static test (p = 0.028) and early in the cyclic test (p = 0.02); differences in the other parameters were not significant. There was a significant correlation between BMD and cycles to failure for the two-screw constructs (r = 0.94; p = 0.002) and for the screw-plus-spiral-blade constructs (r = 0.86; p = 0.014).

CONCLUSION

In TTCA with a HAN Expert Nailing System, the use of a calcaneal spiral blade can further reduce motion within the construct. This may be especially useful in poor bone stock.

CLINICAL RELEVANCE

Results obtained in this study could be used to guide the operating surgeon's TTCA strategy.

Intraoperative mechanical bone strength determination in tibiotalocalcaneal fusion: a biomechanical investigation

BACKGROUND

Bone strength is currently measured with indirect techniques. We investigated the use of an intraoperative mechanical measurement for local bone strength determination and prediction of intramedullary-nail fusion failure. We investigated whether intraoperative local bone strength determination may be useful to the surgeon in predicting intramedullary nail hindfoot fusion performance.

MATERIALS AND METHODS

In seven human specimens, bone mineral density (BMD) was determined with qCT. A device (DensiProbe) specially devised for nailed tibiotalocalcaneal arthrodesis (TTCA) was inserted at the intended calcaneal screw sites of an intramedullary nail, and the cancellous break-away torque was measured. The constructs were then cyclically loaded to failure in dorsiflexion-plantarfexion.

RESULTS

The BMD range was wide (42.8 to 185.9 mg HA/cm(3)). The proximal-screw site peak torque was 0.47 to 1.61 Nm; distal-screw site peak torque was 0.24 to 1.06 Nm. The number of cycles to failure correlated with peak torque both proximally (p = 0.021; r(2) = 0.69) and distally (p = 0.001; r(2) = 0.92). Proximally, peak torque did not correlate with BMD (p = 0.060; r(2) = 0.54); distally, it correlated significantly (p = 0.003; r(2) = 0.86).

CONCLUSION

DensiProbe measurements can be used in the hindfoot to assess bone strength. In this study, specimens that failed early could be identified. However, in clinical practice fusion failure is multifactorial in origin, and failure prediction cannot be based upon peak torque measurements alone.

CLINICAL RELEVANCE

The technique described here may be of use to give an intraoperative decision aid to predict intramedullary nail hindfoot fusion performance.

Treatment of nonunion and malunion of trauma of the foot and ankle using external fixation

Salvage of nonunion and malunion of trauma of the foot and ankle is often challenging surgery. Internal fixation provides the mainstay of most orthopedic surgeons' treatment of these conditions. Patient systemic factors, local factors, and the complex nature of these often multiplanar deformities may make external fixation a more viable option. This article provides an overview of the principles and results of the use of external fixation.

Tibiotalocalcaneal arthrodesis with the use of a humeral locking plate

Combined arthrosis or deformity of the subtalar and ankle joints presents a challenge to the foot and ankle specialist. Tibiotalocalcaneal arthrodesis is a well-described surgical technique used for resolution of deformity and end-stage arthrosis of the ankle and subtalar joints and is currently the standard of care for this condition. This article highlights the technique of insertion of the humeral locking plate for the stabilization of tibiotalocalcaneal arthrodesis. A case study is provided to serve as an example of the technique.