Introduction
Subtalar arthroereisis is commonly used to limit excessive pronatory motion of the subtalar joint. The term arthroereisis can be described as the limitation of motion in an excessively mobile joint (1-3). Functionally a subtalar joint arthroereisis prevents excessive pronation by stabilizing the calcaneus under the talus (2,4-6). It has been utilized for tibialis posterior dysfunction (TPD) as well as juvenile flexible flatfoot. The implant is thought to act as an "internal orthotic" (7) placing the hindfoot in proper alignment. It is hoped that over time, the implant will allow for adaptation of the soft-tissue structures, thus, diminishing the deforming forces that created the deformity. Our institution has been utilizing an isolated subtalar arthroereisis procedure for the treatment of stage I tibialis posterior dysfunction (8). .
MATERIALS AND METHODS
Between August 2003 and June 2004, seven feet on seven patients had a subtalar arthroereisis performed as an outpatient procedure for stage I TPD. Four patients were treated with the use of a Kalix implant (Newdeal SA, Lyon, France) and three patients had an absorbable implant (poly-L-lactic acid Bio-Tenodesis screw, Arthrex - Naples, FL). Diagnosis was made on the basis of clinical and radiographic evaluation. All patients had Magnetic Resonance Imaging (MRI) performed prior to any surgical management revealing significant fluid surrounding the posterior tibial tendon(Figure 2).
All patients had an Emed (Novel, Berlin, Germany) footprint analysis pre-operatively (Figure 4) revealing increased pressure distribution in the medial aspect of the midfoot. All patients had clinically reducible deformities and were non-responsive to conservative treatment. The procedure is performed under intravenous anesthesia and infiltrative local anesthetic (0.5% bupivicaine plain). A 1cm incision is made over the lateral aspect of the sinus tarsi along relaxed skin tension lines. The deep fascia is then incised and penetrated with the use of a Kelly hemostat. The hemostat is advanced through the sinus tarsi from lateral to medial as far as possible.
The hemostat is removed and an arthroereisis sizer is placed into the sinus tarsi. It is advanced lateral to medial until adequate correction is achieved (Figure 1). This is determined by everting the foot until restriction excessive pronation is accomplished. The sizer measurement at this point determines the implant size to be used. The appropriate sized implant is then placed on the insertion device and it is then used to insert the screw into the sinus tarsi. The procedure is now performed under mini c-arm fluoroscopy control. The implant is inserted firmly to a point where the tip of the insertion device meets the lateral margin of the talar neck on an AP view. The insertion device is then removed, deep fascia repaired, and wound closed in a subcuticular fashion with absorbable suture. Patients were then placed in a cam walker with partial weight bearing allowed.
IMAGES AND TABLES
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RESULTS
Six left feet and one right foot with stage I TPD were surgically corrected with the use of an isolated subtalar joint arthroereisis technique. The patient age range was 21-80 years of age with a mean age of 54. All seven patients were female. All patient's complaints of severe pain were absent post-operatively. MRI obtained 16 weeks postoperatively revealed a decrease in fluid surrounding the posterior tibial tendon (Figure 3). A 6 month postoperative Emed revealed a more appropriate pressure distribution (Figure 5). No signs of cyst formation due to the implant were noted on any radiographic views or magnetic resonance imaging post-operatively. There were no local or systemic reactions noted to the implant. Two implants required removal due to pain at the level of the sinus tarsi post-operatively; one Kalix implant three months post-operatively and one absorbable implant at four months postoperatively. All patients had radiographic increased talar coverage percentage, decreased talar declination angle, increased calcaneal inclination angle and decreased cuboid abduction angle post-operatively versus pre-operative radiographic evaluation.
Conclusion
Subtalar joint arthroereisis is a viable option for treatment for early stage tibialis posterior dysfunction. It has been documented over time to be a useful and simple procedure for the correction of the flexible flatfoot in children and acquired flatfoot deformity in adults. The procedure provides decreased inflammation and support of the posterior tibial tendon in a corrected position during the repair period to allow for adaptation of the foot (2,4,7). The advantages of the technique include ease of technique, minimal morbidity, and progressive correction of the deformity.
References
1. Roye DP, Raimondo RA. Surgical treatment of the child's and adolescent's flexible flatfoot. Clin Podiatr Med Surg 2000;17:515-530
2. Maxwell J, Nakra A, Ashley C. Use of the Maxwell-Brancheau arthroereisis implant for the correction of posterior tibial tendon dysfunction. Tech Orthop 2000;15:183-196.
3. LiLievre J. Current concepts and correction in the valgus foot. Clin Orthop 1970;70:43-55.
4. Viladot R, Pons M, Alvarez F, et al. Subtalar arthroereisis for posterior tibial tendon dysfunction: a preliminary report. Foot Ankle 24:600-60, 2003;24:600-606.
5. Maxwell JR, Carro A, Sun C. Use of the Maxwell-Brancheau arthroereisis implant for the correction of posterior tibial tendon dysfunction. Clin Podiatr Med Surg 1999;16:479-489.
6. Subotnick SI. The subtalar joint lateral extra-articular arthroereisis: A follow-up report. J Am Podiatr Assoc 1977;67:157-171.
7. Zaret DI, Myerson MS. Arthroerisis of the subtalar joint. Foot Ankle Clin N Am 2003;8:605-617.
8. Johnson KA, Strom DE. Tibialis posterior tendon dysfunction. Clin Orthop1989;239:197-206.
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