Biomechanical analysis of screw-augmented intramedullary fixation for tibiotalocalcaneal arthrodesis

Clinical outcomes following tibiotalocalcaneal arthrodesis with intramedullary nailing combined with partial fibulectomy and onlay bone graft

INTRODUCTION

Although intramedullary nailing is a popular method for tibiotalocalcaneal arthrodesis, nonunion is one of the most commonly reported complications. This study aimed to evaluate the fusion rate, improvement in functional outcomes, and occurrence of complications in tibiotalocalcaneal arthrodesis using retrograde intramedullary nailing with partial fibulectomy and onlay bone graft technique.

MATERIALS AND METHODS

Twenty-six consecutive patients using the proposed technique were retrospectively reviewed. For radiographic outcomes, the union rate, alignment, and any related complications were assessed. Functional outcomes were evaluated using the American Orthopedic Foot and Ankle Society hindfoot scale, Foot and Ankle Outcome Score, and visual analog scale, preoperatively and at the final follow-up.

RESULTS

The mean follow-up period was 38.2 months. The tibiotalar joint achieved complete union in 80.8% at six months postoperatively, while all the cases achieved complete union at 12 months postoperatively. However, the subtalar joint achieved complete union in 26.9% at six months postoperatively, which gradually increased to 73.1% at 12 months postoperatively, and 80.8% at the final follow-up without revision surgery. A subgroup analysis showed there was a trend of higher subtalar fusion rate when an additional screw for the subtalar joint fixation was placed (86.7% vs. 54.5%). The functional outcomes significantly improved at the final follow-up. A few minor complications occurred, including surgical site infection, irritational symptoms, and metal failure; however, they eventually resolved.

CONCLUSIONS

Our technique of tibiotalocalcaneal arthrodesis with partial fibulectomy and onlay bone grafting could be a good option where both the tibiotalar and subtalar joints need to be fused.

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 distal tibial allograft for massive bone deficits in the ankle

BACKGROUND

The purpose of this study was to assess the outcomes of distal tibial structural allograft to obtain a stable TTC fusion.

METHODS

Retrospectively, ten patients were carried out with a minimum one year follow-up. The median age was 72 (33-81). The median BMI was 28 (24-33). Indications for TTC arthrodesis included failed total ankle arthroplasty (n=7 patients), prior nonunion (n=2 patients), and a trauma injury.

RESULTS

Union rate was 80%. The median initial height of the distal tibial allograft was 19mm (14-24mm). In seven cases the allograft did not lose height. The AOFAS score median was 69 (31-84). SF-12 median physical component was 39 (30-53), and 59 (23-62) for mental component. The VAS median was 2 (0-8).

CONCLUSIONS

TTC using distal tibial allograft shows a lower rate of collapse than other structural grafts and provides a fusion rate higher or in accordance with the literature.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Lower Bone Density on Preoperative Computed Tomography Predicts Periprosthetic Fracture Risk in Total Ankle Arthroplasty

BACKGROUND:

The effect of bone mineral density (BMD) on outcomes from total ankle arthroplasty (TAA) has not been studied. BMD can be estimated by measuring Hounsfield units (HU) on standard computed tomography (CT), which is frequently performed prior to TAA. We aimed to identify whether tibial and talar HU measured from preoperative CT scans were associated with periprosthetic fracture or revision risk in patients undergoing TAA.

METHODS:

A prospectively collected database was used to retrospectively screen all patients undergoing primary TAA. Only patients with a preoperative CT within 1 year of surgery were included. Primary outcomes were periprosthetic fracture and prosthetic revision. HU were measured on axial CT cuts in the distal tibia and talus. Additional patient factors analyzed included age, sex, weight, body mass index (BMI), tobacco use, presence of rheumatoid arthritis, and preoperative deformity. A total of 198 ankles were included, with a mean 2.4 years of follow-up.

RESULTS:

There were 7 intraoperative and 9 postoperative periprosthetic fractures (3.5% and 4.5%, respectively). Seven patients (3.5%) underwent prosthetic removal or revision. Lower tibial and talar HU, lower weight, and lower BMI were associated with periprosthetic fractures ( P < .05). After controlling for age, sex, and weight, only tibial HU was significantly associated with periprosthetic fracture ( P = .018). All intraoperative fractures occurred in patients with tibial HU less than 200. None of the patient factors analyzed were associated with revision.

CONCLUSIONS:

Lower tibial HU on preoperative CT was strongly associated with periprosthetic fracture risk with TAA. In patients with tibial HU less than 200, surgeons may consider prophylactic internal fixation of the medial malleolus.

LEVEL OF EVIDENCE:

Level III, retrospective cohort study.

Comparison of Posterior Approach With Intramedullary Nailing Versus Lateral Transfibular Approach With Fixed-Angle Plating for Tibiotalocalcaneal Arthrodesis

BACKGROUND

A variety of operative approaches and fixation techniques have been described for tibiotalocalcaneal (TTC) arthrodesis. The intramedullary (IM) nail and lateral, fixed-angle plating are commonly used because of ease of use and favorable biomechanical properties. A lateral, transfibular (LTF) approach allows for direct access to the tibiotalar and subtalar joints, but the posterior, Achilles tendon-splitting (PATS) approach offers a robust soft tissue envelope. The purpose of this study was to compare the results of TTC arthrodesis with either a PATS approach with IM nailing or LTF approach with fixed-angle plating.

METHODS

A retrospective review was performed on all patients who underwent simultaneous TTC arthrodesis with minimum 1 year clinical and radiographic follow up. Patients were excluded if they underwent TTC arthrodesis through an approach other than PATS or LTF, and received fixation without an IM nail or fixed-angle plate. Primary outcomes examined were union rate, revisions, and complications. Thirty-eight patients underwent TTC arthrodesis with a PATS approach and IM nailing, and 28 with a LTF approach and lateral plating.

RESULTS

The overall union rate was 71%; 76% (29 of 38 patients) for the PATS/IM nail group, and 64% (18 of 28) for LTF/plating group ( P = .41). Symptomatic nonunion requiring revision arthrodesis occurred in 16% (6 of 38) of the PATS/IM nail group versus 7% (2 of 28) in the LTF/lateral plating group ( P = .45). There were no significant differences in individual tibiotalar or subtalar union rates, superficial wound problems, infection, symptomatic hardware, stress fractures, or nerve irritations.

CONCLUSION

Union, revision, and complication rates were similar for TTC arthrodesis performed with a PATS approach and IM nail compared with an LTF approach and fixed-angle plate in a complex patient population. Both techniques were adequate, especially when prior incisions, preexisting hardware, or deformity preclude options.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

3D Optical Investigation of 2 Nail Systems Used in Tibiotalocalcaneal Arthrodesis: A Biomechanical Study

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

CLINICAL RELEVANCE

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.

Biomechanical investigation of two plating systems for medial column fusion in foot

Background

Arthrodesis of the medial column (navicular, cuneiform I and metatarsal I) is performed for reasons such as Charcot arthropathy, arthritis, posttraumatic reconstruction or severe pes planus. However, the complication rate is still high and mainly resulting from inadequate fixation. Special plates, designed for medial column arthrodesis, seem to offer potential to reduce the complication rate. The aim of this study was to investigate biomechanically plantar and dorsomedial fusion of the medial column using two new plating systems.

Methods

Eight matched pairs of human cadaveric lower legs were randomized in two groups and medial column fusion was performed using either plantar or dorsomedial variable-angle locking compression plates. The specimens were biomechanically tested under cyclic progressively increasing axial loading with physiological profile of each cycle. In addition to the machine data, mediolateral x-rays were taken every 250 cycles and motion tracking was performed to determine movements at the arthrodesis site. Statistical analysis of the parameters of interest was performed at a level of significance p = 0.05.

Results

Displacement of the talo-navicular joint after 1000, 2000 and 4000 cycles was significantly lower for plantar plating (p≤0.039) while there was significantly less movement in the naviculo-cuneiform I joint for dorsal plating post these cycle numbers (p<0.001). Displacements in all three joints of the medial column, as well as angular and torsional deformations between the navicular and metatarsal I increased significantly for each plating technique between 1000, 2000 and 4000 cycles (p≤0.021). The two plating systems did not differ significantly with regard to stiffness and cycles to failure (p≥0.171).

Conclusion

From biomechanical point of view, although dorsomedial plating showed less movement than plantar plating in the current setup under dynamic loading, there was no significant difference between the two plating systems with regard to stiffness and cycles to failure. Both tested techniques for dorsomedial and plantar plating appear to be applicable for arthrodesis of the medial column of the foot and other considerations, such as access morbidity, associated deformities or surgeon's preference, may also guide the choice of plating pattern. Further clinical studies are necessary before definitive recommendations can be given.

Outcomes of Tibiotalocalcaneal Arthrodesis Through a Posterior Achilles Tendon-Splitting Approach

BACKGROUND

A number of operative approaches have been described to perform a tibiotalocalcaneal (TTC) arthrodesis. Here we present the largest reported series of a posterior Achilles tendon-splitting approach for TTC fusion.

METHODS

With institutional review board approval, a retrospective review of the TTC fusions performed at a single academic institution was carried out. Orthopedic surgeons specializing in foot and ankle surgery performed all procedures. Eligible patients included all those who underwent a TTC fusion via a posterior approach and had at least a 2-year follow-up. Forty-one patients underwent TTC arthrodesis through a posterior Achilles tendon-splitting approach. Mean age at surgery was 56.9±15.0 years. There were 21 female and 20 male patients. Preoperative diagnoses included arthritis (n = 13 patients), failed total ankle arthroplasty (9), avascular necrosis of the talus (9), prior nonunion of the ankle and/or subtalar joint (6), Charcot neuro-arthropathy (2), and stage IV flatfoot deformity (2). In 37 patients (90.2%), a hindfoot intramedullary arthrodesis nail was used, with posterior plate or supplemental screw augmentation in 17 patients. Posterior plate stabilization alone was utilized in 4 cases (9.8%).

RESULTS

The fusion rate was 80.4%. Eight patients developed a nonunion of the subtalar, tibiotalar, or both joints. Complications were observed in 17 patients (41.4%). Of these, ankle nonunion (19.5%), tibial stress fracture (17%), postoperative cellulitis and superficial wound breakdown (9.7%), subtalar nonunion (4.8%), and TTC malunion (2.4%) were the most frequently identified. One patient eventually underwent amputation (2.4%).

CONCLUSION

We believe that posterior Achilles tendon-splitting approach for tibiotalocalcaneal arthrodesis was a safe and effective method, with similar union and complications rates to some previously described techniques. We believe the posterior approach is advantageous as it provides simultaneous access to both the ankle and subtalar joints and allows for dissection to occur between angiosomes, which may preserve blood supply to the skin.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Tibiotalocalcaneal Fusion for Severe Deformity and Bone Loss

Tibiotalocalcaneal fusion is an effective salvage procedure for combined end-stage ankle and subtalar arthrosis and for the management of severe planar deformities of the ankle and hindfoot. Although the procedure results in a rigid ankle and hindfoot, it is often the only means of providing patients with a stable and painless foot and ankle for ambulation. Some patients who require the procedure have substantial bone loss that can be managed with a variety of autograft and allograft options. Options for tibiotalocalcaneal fixation include both internal and external devices, the selection of which depends on the underlying pathology, amount of bone loss, and type of bone graft selected. Relatively high complication rates associated with tibiotalocalcaneal fusion have been reported, with complications ranging from superficial infection to ultimate amputation; however, proper patient selection and careful graft and fixation planning can minimize the postoperative complications of the procedure.

Application of the First Expert Arthrodesis Nail to a Patient with Previous Performed Arthrodesis According to Ulrich Holz – Case Report

AIM: The aim of this paper was to present application of the first expert arthrodesis nail in our clinic to a patient with previous performed arthrodesis according to Ulrich Holz.CASE REPORT: Patients A.M. on the age of 22 (1992) have a motor vehicle injury, (fall from a motor bike) with diagnosis polytrauma, shock, supra and transcondyar open fracture of the right femur III degree, open fracture of the right tibia and fibula. We perform reposition and fixation of supra and transcondyar femoral fracture with “cobra” plate. Also we perform reposition and fixation of right cruris with external fixation. After the operation we found fistula in the place of operation of the right crural regia. During the time the infection goes worse and the patient develop osteomyelittis on the right crural regia. After 5 months with therapy the situation become calm. We remove the external fixation. The patient develops severe “pes equinus” on the right leg and he cannot walk. We try to reduce this equines situation with elongation of the Achilles tendonin the first step, and because we didn’t solve the problem we continue with complete section of the Achilles tendon and after that we perform osteotomy of the right talocrural joint simultaneous to tibia plafond and talus and resection of fibula 2sm.above the syndesmosae tibiofibularis and we fixed the talocrural joint with two screws according the technique of Ulrich Holz.CONCLUSION: So we received fixed position on of the food on 110 degrees which was steel unacceptable for normal walking. At last we remove the screws, make once again osteotomy with positioning of the food in maximal dorsiflexion and perform the Experf Hindfood arthrodesis nail so with this method we achieve correction of dorsiflexion on 95 degrees, and the patient become satisfied because he can walk without support.

Biomechanical comparison of stability of tibiotalocalcaneal arthrodesis with two different intramedullary retrograde nails

BACKGROUND

The aim of the study was to compare the initial construct stability of two retrograde intramedullary nail systems for tibiotalocalcaneal arthrodesis (TTCF) (A3, Small Bone Innovations; HAN, Synthes) in a biomechanical cadaver study.

METHODS

Nine pairs of human cadaver bones were instrumented with two different retrograde nail systems. One tibia from each pair was randomized to either rod. The bone mineral density was determined via tomography to ensure the characteristics in each pair of tibiae were similar. All tests were performed in load-control. Displacements and forces were acquired by the sensors of the machine at a rate of 64Hz. Specimens were tested in a stepwise progression starting with six times ±125N with a frequency of 1Hz for 250cycles each step was performed (1500cycles). The maximum load was then increased to ±250N for another 14 steps or until specimen failure occurred (up to 3500cycles).

RESULTS

Average bone mineral density was 67.4mgHA/ccm and did not differ significantly between groups (t-test, p=.28). Under cyclic loading, the range of motion (dorsiflexion/plantarflexion) at 250N was significantly lower for the HAN-group with 7.2±2.3mm compared to the A3-group with 11.8±2.9mm (t-test, p<0.01). Failure was registered for the HAN after 4571±1134cycles and after 2344±1195cycles for the A3 (t-test, p=.031). Bone mineral density significantly correlated with the number of cycles to failure in both groups (Spearman-Rho, r>.69, p<0.01).

CONCLUSIONS

The high specimen age and low bone density simulates an osteoporotic bone situation. The HAN with only lateral distal bend but two calcaneal locking screws showed higher stability (higher number of cycles to failure and lower motion such as dorsiflexion/plantarflexion during cyclic loading) than the A3 with additional distal dorsal bend but only one calcaneal locking screw. Both constructs showed sufficient stability compared with earlier data from a similar test model.

CLINICAL RELEVANCE

The data suggest that both implants allow for sufficient primary stability for TTCF in osteoporotic and consequently also in non-osteoporotic bone.

LEVEL OF EVIDENCE

Not applicable, experimental basic science study.

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.

Tibiotalocalcaneal arthrodesis with combined retrograde intramedullary nail and lateral L-plate

Achieving stable fixation when performing tibiotalocalcaneal or tibiocalcaneal arthrodesis can be challenging. Patients undergoing these procedures often have osteopenia, poor bone stock, fragmentation of the bones of the foot and ankle, joint subluxation, or even dislocation. The author describes a technique of tibiotalocalcaneal arthrodesis with intramedullary nail fixation augmented by lateral plating through the transfibular approach. This can provide excellent exposure of the ankle and subtalar joints, morselized bone for grafting, and better construct stability.

Plantar versus dorsomedial locked plating for Lapidus arthrodesis: a biomechanical comparison

BACKGROUND

Lapidus arthrodesis with a plate and a compression screw is an established procedure in hallux valgus surgery. The present study was performed to investigate the potential benefit of a compression screw combined with a plantarly applied angle-stable, anatomically precontoured plate or a dorsomedially applied angle-stable plate.

METHODS

In six pairs of human cadaver specimens, one specimen each was randomized to receive a dorsomedial H-shaped plate, while the other received a plantar plate. Bone mineral density was measured with peripheral quantitative computed tomography. The specimens were loaded quasi-statically, followed by cyclic loading. Finally, they were loaded to failure. In the static tests, stiffness and range of motion (ROM) data were obtained. In the cyclic tests, the constructs' displacement was studied. In the load-to-failure test, stiffness and maximum load to failure were measured.

RESULTS

The two groups did not differ significantly with regard to BMD (p = 0.25). Any significant differences observed were in favor of the plantar constructs, which had greater initial stiffness (p = 0.028) and final stiffness (p = 0.042), a smaller ROM (p = 0.028), and a greater load to failure (p = 0.043). There was no significant difference regarding displacement (p = 0.14).

CONCLUSION

In the static tests, the plantar angle-stable plate construct was superior to the dorsomedial angle-stable plate construct.

CLINICAL RELEVANCE

Plantar plating appears to offer biomechanical benefit. Clinical studies will be required to show whether this translates into earlier resumption of weightbearing and into lower rates of nonunion.

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.

Arthroscopic tibiotalocalcaneal arthrodesis with intramedullary nail with fins: a case series

Arthroscopic arthrodesis of the ankle has several advantages compared with open arthrodesis, including a smaller skin incision, less damage to the soft tissue around the joint, a lower risk of skin necrosis and infection, a lower incidence of postoperative infection and swelling, and better preservation of the contour of the surface of the joint, which maintains a larger contact area between the talus and tibia. We successfully performed arthroscopic arthrodesis of the tibiotalocalcaneal joints with intramedullary nails with fins in 9 ankles of 8 patients. Solid fusion was attained in all cases, except for 1 case of nonunion at the subtalar joint. We also corrected the alignment in 1 patient with a varus deformity. The fixation was strong, even in the case of poor bone quality, such as occurs in rheumatoid arthritis. The intramedullary nails with fins allowed for appropriate compression for bone consolidation without loss of rotational stability. Arthroscopic tibiotalocalcaneal arthrodesis, a less-invasive technique than conventional open surgery, is effective treatment, especially in patients with poor skin conditions secondary to diseases such as rheumatoid arthritis and diabetes mellitus.

Pantalar arthrodesis for post-traumatic arthritis and diabetic neuroarthropathy of the ankle and hindfoot

BACKGROUND

Pantalar arthrodesis is an important salvage option for stabilizing the hindfoot and salvaging the limb following trauma or collapse. This report evaluates the healing rates and complications which occur in diabetics and post-traumatic patients.

MATERIALS AND METHODS

Twenty patients presenting with post-traumatic arthritis of the ankle-hindfoot (twelve) or with Type II or Type IIIA Charcot arthropathy (eight) were managed with a pantalar fusion. Followup averaged 46 months. Patients were evaluated using the Short Form-36 (SF-36), the American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot score, the Short Musculoskeletal Function Assessment (SMFA) and the Visual Analog Pain Scale (VAS).

RESULTS

There were no amputations in either group. Casting averaged 14.9 weeks, full weightbearing was achieved at 25.1 weeks and time to union averaged 44.1 weeks. Average age was 56.3 yrs. and BMI averaged 34.2. Fourteen patients (70%) had their surgery performed in multiple stages. Acceptable outcomes were noted for all patients for the SF-36, AOFAS and SMFA scores. VAS scores averaged 2.2. There were ten complications (50%); four patients (two in each group) required additional surgery.

CONCLUSIONS

Pantalar arthrodesis is a reasonable salvage option for patients with severe post traumatic arthropathy and neuropathic arthropathy. Patients should be informed of the increased risks as well as the long periods of postoperative immobilization and nonweightbearing. We believe a pantalar arthrodesis can produce acceptable outcomes regardless of the cause of disability, with a staged or single approach, and whether the surgery is performed with plates and screws or an intramedullary device.

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.

Comparison of initial compression of the medial, lateral, and posterior screws in an ankle fusion construct

BACKGROUND

One of the requirements for successful ankle arthrodesis is adequate compression by the fixation across the fusion surfaces. A common screw construct for ankle fusion is three crossed screws from proximal-to-distal. Because the screws are inserted nearly orthogonal to each other, it is possible minimal additional compression is obtainable once the first screw is inserted. The aim of this study was to determine which of the three screws gave the greatest initial compression and theoretically should be inserted first.

MATERIALS AND METHODS

Seventeen cadaver limbs were dissected to expose the anterior and posterior aspects of the tibiotalar joint. Three Fuji film templates were created for each ankle joint with a hole to accommodate a 7.0-mm cannulated screw. Each film was tested with a single medial, lateral, or posterior screw. The Fuji films were then analyzed for contact area, percent contact area, and pressure.

RESULTS

There was no difference in the total contact area, percent contact area, or pressure generated between the three screws. The mean contact area for all screws was 11% of the joint surface. All three screws had greater contact area and percent contact area over the anterior half of the ankle joint.

CONCLUSION

The medial, lateral, and posterior screws were equivalent with respect to contact area, percent contact area, and pressure generated across the tibiotalar joint. All three screws had greater contact area over the anterior half of the joint. Only 11% of the tibiotalar joint surface came in contact following the insertion of a single partially threaded screw.

CLINICAL RELEVANCE

In a neutrally aligned ankle arthrodesis the order of screw insertion does not affect the amount of compression ultimately achieved at the fusion site.

Evaluation of a fiber reinforced drillable bone cement for screw augmentation in a sheep model--mechanical testing

We evaluated the mechanical properties of a novel fiber reinforced calcium phosphate at time zero and after 12 weeks in vivo using a sheep long bone osteotomy model. Time zero data were obtained and compared by pullout testing of 4.5 mm bone screws from bone proper and overdrilled defects of 4.5 and 8 mm diameter. Defects were augmented with: polymethylmethacrylate (PMMA), calcium phosphate, and fiber reinforced calcium phosphate using cadaveric sheep tibiae. Twelve-week data were obtained from explanted tibiae of sheep that underwent unilateral tibial osteotomy surgery repaired with a locking compression plate. The most distal hole was overdrilled to 4.5 or 8 mm diameter, filled with fiber reinforced cement, drilled, tapped and a 4.5 mm screw was placed. Screw holding strength at t= 0 was significantly higher for reinforced when compared to nonreinforced cement, but not different from bone or PMMA in 4.5 mm defects. There was no difference in pullout strength for the 8 mm defect data. After 12 weeks fiber reinforced pullout strength increased by 45% and 8.9% for 4.5 and 8 mm defects, respectively, when compared to t= 0 testing. Fiber reinforced calcium phosphate bone cement can be drilled and tapped to support orthopedic hardware for trauma applications.

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.

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

BACKGROUND

Methods of achieving tibiotalocalcaneal arthrodesis include intramedullary nailing, crossed lag screws, blade plates, and external fixation. While reports in the orthopaedic literature have compared the biomechanical properties of some of these fixation techniques, to our knowledge none has evaluated multiplanar external fixation. The purpose of this study was to compare the biomechanical properties of intramedullary nail fixation and external ring fixation for tibiotalocalcaneal arthrodesis.

MATERIALS AND METHODS

Tibiotalocalcaneal arthrodesis was performed on ten matched pairs of fresh-frozen human cadaveric legs. A ring fixator stabilized the arthrodesis in one leg from each pair and a 10 mm x 150 mm nail inserted retrograde across the subtalar and ankle joint stabilized the arthrodesis in the contralateral leg. The bending stiffness of the resulting constructs was quantified in plantarflexion, dorsiflexion, inversion, and eversion, and torsional stiffness was measured in internal and external rotation.

RESULTS

No difference in bending stiffness between the two constructs was identifiable in any of the four bending directions (p > 0.05). Torsional stiffness was approximately two-fold greater in both internal and external rotation in specimens with the ring fixator arthrodesis than in those with the intramedullary nail (p = 0.002).

CONCLUSION

The ring fixator provides a stiffer construct than a 10 mm x 150 mm intramedullary nail in torsion, but no difference in bending stiffness was demonstrable. Both techniques can provide satisfactory fixation; however, the ring fixator may better minimize rotational joint motion.

CLINICAL RELEVANCE

This study provides a basis for selecting an arthrodesis method that offers optimized fixation.

Rigidity comparison of locking plate and intramedullary fixation for tibiotalocalcaneal arthrodesis

BACKGROUND

Obtaining adequate fixation during tibiotalocalcaneal (TTC) arthrodesis may be challenging. Various fixation constructs have been tested biomechanically, but the use of a locking plate has not been reported. We hypothesized that the locking plate with a TTC augmentation screw would provide structural rigidity comparable to that of the intramedullary (IM) nail with a TTC augmentation screw during dorsiflexion testing.

MATERIALS AND METHODS

Six matched pairs of fresh frozen cadavers underwent TTC arthrodesis. Specimens in each pair were randomized to receive a locking plate or an intramedullary nail. Each specimen had an additional TTC augmentation screw through the calcaneus, talus, and medial tibia. All samples underwent dorsiflexion testing with determination of structural rigidity at the first cycle (initial rigidity) and last cycle (final rigidity) and the torque required to achieve a failure of 10 degrees of dorsiflexion. Statistical analysis was performed using a paired t-test to determine whether any differences were significant (p < 0.05).

RESULTS

The locking plate construct showed higher final rigidity (mean +/- standard error of the mean) (27.7 +/- 2.6 N-m/degree versus 17.6 +/- 2.1 N-m/degree, p = 0.01) than the IM nail construct. There were no other differences measured.

CONCLUSION

Rigidity with the the IM nail was inferior to that with locking plate fixation for TTC arthrodesis in one of the four parameters tested.

CLINICAL RELEVANCE

Screw augmented IM nail fixation and augmented locking plate fixation may offer similar rigidity clinically for TTC arthrodesis.

Blade plate compared with locking plate for tibiotalocalcaneal arthrodesis: a cadaver study

BACKGROUND

We hypothesized that a locking plate would be stronger than a blade plate for tibiotalocalcaneal arthrodesis under dorsiflexion and torsional loading.

MATERIALS AND METHODS

Nine pairs of matched cadaveric lower extremities were used. BMD was obtained for each specimen. Each received a retrograde augmentation screw and a stainless steel LC-angled blade plate (Synthes, Paoli, PA) or a stainless steel LCP proximal humerus locking plate (Synthes, Paoli, PA). Specimens were cyclically loaded in dorsiflexion to simulate 6 weeks of partial weightbearing and then monotonically loaded to failure. Specimens were removed from the load frame and remounted to simulate fusion. The specimen received an axial load of 720 N and was externally rotated proximal to the construct at 5 degrees/sec to fracture. Data were compared with a Student's t-test. Pearson correlation analysis was used to determine whether bone mineral density was significantly related to measured parameters. Significance was set at p < or = 0.05.

RESULTS

The locking plate group had higher initial stiffness, higher dorsiflexion and torsional load to failure, and lower construct deformation than the blade plate group. Bone mineral density was positively correlated with dorsiflexion failure load and torsional failure load in the locking plate construct.

CONCLUSION

Fixation with the locking plate was superior to that with the blade plate.

CLINICAL RELEVANCE

Use of a locking plate may be an effective fixation technique in tibiotalocalcaneal arthrodesis, especially in complex hindfoot reconstructions with bone loss or deformity.