Subtalar joint distraction arthrodesis utilizing titanium truss technology for posttraumatic calcaneal fracture arthritis





Definition




  • •

    Posttraumatic subtalar joint distraction arthrodesis utilizing porous titanium wedge spacers in order to restore talar tilt and renew ankle joint range of motion as well as fuse the subtalar joint to treat pain.



Anatomy




  • •

    The subtalar joint is a complex triplanar joint consisting of the inferior surface of the talus and the superior surface of the calcaneus.


  • •

    There are three articulations between the two tarsal bones that make up the joint—the anterior, middle, and posterior facets.


  • •

    Normal positioning of the joint would be considered a rectus vertical position with no signs of either varus or valgus tilt. Traditional literature states the normal position would include a complete neutral position with allowable deformity to up to 5 degrees of hindfoot valgus.


  • •

    Calcaneal fractures generally lead to deformity and malposition of the subtalar joint. Deformity seen with calcaneal fractures is a result of both primary and secondary fracture lines.


  • •

    In general, the calcaneus is shortened and flattened with varus malalignment after severe calcaneal fractures. This is demonstrated radiographically by a decrease in Bohler’s angle, an increase in Gissane’s angle, and a horizontal position of the talus with a decreased talar declination angle on lateral radiographs.


  • •

    This varus position of the subtalar joint also leads to impingement of the talar neck to the tibia with ankle joint dorsiflexion secondary to varus position of the talus, including minimal-to-negative talar declination angle ( Fig. 13.1 ). , ,




    • Fig. 13.1


    Preoperative radiographs showing varus deformity secondary to intraarticular calcaneal fracture. (A) Lateral foot radiograph. (B) Calcaneal axial radiograph.


  • •

    Unless these deformities are corrected, they will ultimately lead to posttraumatic arthritis of the subtalar joint, anterior ankle impingement, and structural equinus.



Pathogenesis




  • •

    Varus malalignment of the subtalar joint may be secondary to:



    • •

      Genetic hindfoot varus deformity


    • •

      Acquired hindfoot varus deformity


    • •

      Intra-articular, depression calcaneal fractures/trauma


    • •

      Malunion of previous subtalar joint arthrodesis.



  • •

    Genetic varus deformity is generally secondary to a group of inherited disorders that cause peroneal nerve injury. These generally fall into a category of disorders under the term Charcot-Marie-Tooth (CMT) disease. Although there are other disorders, CMT is generally the most common.


  • •

    Acquired hindfoot varus deformity develops via one of two routes. Injury of the superficial peroneal nerve or injury to the peroneal tendons. This imbalance within the foot generally leads to overpowering of the tibialis posterior tendon, which leads to hindfoot varus.


  • •

    As stated above, intraarticular depression calcaneal fractures generally lead to varus malalignment of the hindfoot.


  • •

    Primary subtalar joint arthrodesis, if not carefully evaluated, may lead to varus malunion and hindfoot deformity, leading to similar difficulties.



Patient history and physical findings




  • •

    Localized/diffuse pain throughout the subtalar joint and anterior ankle joint.


  • •

    Limited and painful range of motion of the subtalar joint.


  • •

    Pain with a hard stop with ankle dorsiflexion (structural equinus).


  • •

    Pain and weakness of the peroneal tendons.


  • •

    Lateral ankle instability with possible laxity and pain with anterior drawer and inversion stress test.


  • •

    Hindfoot varus position in a neutral stance. Deformity may be reducible or not. Generally, a Coleman block test shows a hindfoot origin of deformity.


  • •

    Difficulty with weight-bearing activities including walking.


  • •

    Neurovascular compromise with peroneal nerve testing (common and superficial peroneal nerves).



Imaging and other diagnostic testing




  • •

    Radiographs:



    • •

      On lateral view, a nontraumatic patient will show a bullet hole sinus tarsi sign, increased calcaneal inclination greater than 25 degrees, an increased talar-1st metatarsal angle greater than 5 degrees, and Hibb’s angle greater than 45 degrees.


    • •

      Lateral view in traumatic patients will identify the above along with a decrease in Bohler’s angle (less than 30 degrees and an increase in critical angle of Gissane greater than 130 degrees).


    • •

      Most important for this procedure is whether the talus position has a decreased to negative talar declination angle less than 25 degrees and a tibiotalar angle greater than 105 degrees.


    • •

      Calcaneal axial views are also recommended in order to identify the amount of varus deformity of the subtalar joint. Normal values should be neutral to no more than 5° of valgus. This will prepare the surgeon as to how much varus needs to be addressed during the joint-preparation portion of the procedure.


    • •

      With standard radiographs evaluation for ankle varus should be performed and evaluation for metatarsus adductus should also be evaluated.



  • •

    Advanced imaging (MRI):



    • •

      MRI is useful for evaluating the soft tissue injury, which can occur with varus deformity of the hindfoot or which can act as the initial injury to progress to varus deformity ( Fig. 13.2 ).




      • Fig. 13.2


      Preoperative MRI showing peroneal tendon pathology with subluxation, and subtalar joint degeneration. (A) Axial T1 MRI view. (B) Coronal T1 MRI view.


    • •

      Structures to evaluate carefully would include the peroneal tendons and retinaculum, the anterior talofibular ligaments, the calcaneal fibular ligament, and the posterior talofibular ligament.


    • •

      Other structures to evaluate would be the subtalar and ankle joint for signs of degeneration, avascular necrosis, and inflammation.


    • •

      Although fusion of the subtalar joint does limit varus and valgus rotation of the hindfoot, repair of the soft tissues should always be considered for long-term protection of the ankle joint.



  • •

    Other testing:



    • •

      Electromyography and nerve conduction–velocity studies should be considered for patients with neurological compromise concerns.


    • •

      Noninvasive vascular studies should be considered for patients with a poor vascular exam and patients with a smoking history.


    • •

      Genetic testing should be considered for patients with genetically caused cavus foot concerns.


    • •

      Vitamin D testing should be done to optimize patient healing before, during, and after the procedure. Patients with low vitamin D levels are generally supplemented with vitamin D 50,000 IU per week or 5000 IU per day throughout preoperative and postoperative periods.


    • •

      Cotinine/nicotine testing.




Nonoperative management




  • •

    Ankle foot orthosis (AFO) bracing including Richie, Arizona, and custom posterior leaf AFO.


  • •

    Orthotic treatment for mild deformity with minimal ankle symptoms. May consider a University of California Berkeley Laboratories (UCBL) device for more hindfoot deformity control.


  • •

    Immobilization.


  • •

    Rest, ice, compression, elevation (RICE) therapy and nonsteroidal antiinflammatory drugs.


  • •

    Oral steroid packs or subtalar and ankle joint steroid injections.



Traditional surgical management: Concerns and disadvantages




  • •

    The use of structural autografts and allograft wedges for subtalar joint distraction arthrodesis has traditionally been used for this specific procedure.


  • •

    Structural autografts from the iliac crest have been the gold standard for reestablishing talar declination in subtalar joint distraction arthrodesis.


  • •

    Unfortunately, autografts are associated with an up to 41% risk of donor site morbidity, large hematomas in 9.6% of patients, and wound dehiscence at the donor site in 2.7% of patients.


  • •

    Autografts have also been associated with elongated hospital stay, limited quantity and size options, and poor-quality grafts in patients with poor protoplasm.


  • •

    In order to combat donor site complications, allografts, particularly frozen femoral head allografts, have also been discussed at length within the literature as an acceptable alternative to using autografts for subtalar joint distraction arthrodesis.


  • •

    Although allograft use does limit the donor site morbidity seen with autograft use, both have been associated with graft collapse and a relatively high nonunion rate over the long term. This is secondary to the structural graft’s inability to withstand the excessive forces from axial loading. ,


  • •

    Allograft use also carries the risk of disease transmission; however, the incidence of this occurring is exceptionally low.


  • •

    In situ fusion has also been used as an option. Unfortunately for these patients, this generally leads to significant ankle pathology over time.



Titanium truss design specifications and considerations




  • •

    An alternative to structural bone grafts is the use of structural titanium trusses. These implants inherently prevent the donor site morbidity associated with autografts, as well as the collapse and failure seen with structural bone grafts in general.


  • •

    Titanium has shown to be osteoconductive, with minimal bioactivity of concern for an allergic response.


  • •

    The porous nature of the graft also allows the surgeon to make the osteoconductive titanium also become osteogenic and osteoinductive with the addition of orthobiologics within the porous structures.


  • •

    The authors generally use a wedge-shaped truss design that allows for an increased talar declination position with fixation.


  • •

    The authors use a company with multiple truss widths and heights, which come standard along with multiple sizers in order to identify the most optimal implant for each patient.


  • •

    Although custom-designed implants can be used with the creation of holes for fixation, the authors have found an excellent construct that allows for cost savings and adequate fixation and compression at the fusion sites.


  • •

    Truss size and shape is decided with the use of joint distraction along with fluoroscopy evaluation.


  • •

    Titanium trusses, cages, and trabecular porous wedges have been discussed throughout the literature as successful means to bridge bony deficits. Reports in the orthopedic literature have shown successful use with bridging large bony defects for hip and knee arthroplasties, spinal fusions, cranioplasty plates, and pacemaker electrodes.


  • •

    The use of titanium trusses within foot and ankle surgery is relatively new, with the earliest literature ranging from 2004 by Bouchard et al. to recent studies by Coriaty et al. and So et al. in 2018. All of the studies have shown excellent bony ingrowth with long-term stability. ,



Surgical management with a titanium truss for subtalar joint distraction arthrodesis



Tags:
Jul 15, 2023 | Posted by in ORTHOPEDIC | Comments Off on Subtalar joint distraction arthrodesis utilizing titanium truss technology for posttraumatic calcaneal fracture arthritis

Full access? Get Clinical Tree
Get Clinical Tree app for offline access