Posters

Report of Union and Complication Rates of Bone Allograft used in the Anterior Calcaneal Osteotomy for Pediatric and Adult Flatfoot
Shine John DPM, Brandon Child DPM, Joel Hix DPM
Mike Maskill DPM, Alan R. Catanzariti DPM, FACFAS, Robert W. Mendicino DPM, FACFAS
Division of Foot and Ankle Surgery - Department of Surgery - The Western Pennsylvania Hospital - Pittsburgh, PA

Abstract

The anterior calcaneal osteotomy is a commonly performed and successful procedure for treatment of the symptomatic pediatric and adult flatfoot. A successful outcome is dependent upon appropriate placement, stability, and incorporation of a bone graft. Literature is remiss when reporting the use of allograft in the surgical procedure. Allografts are readily available, require no additional incisions, and have shown comparable union rates when compared to autografts. Despite some fears of disease transmission only a few reported cases are available. These cases were reported in the 1980s when safety protocols were less stringent. Currently they have proven to be relatively safe. For these and other reasons the authors utilize allograft bone when performing an anterior calcaneal osteotomy. This poster reports the union and complication rates on a series of patients who underwent an anterior calcaneal osteotomy with use of allograft.

Materials and Methods

A retrospective review of charts and radiographs was performed on pediatric and adult patients who underwent an anterior calcaneal osteotomy performed with use of an allogenic bone graft. All patients who underwent an anterior calcaneal osteotomy for the correction of a painful flatfoot between January 2003 and July 2007 were included in the study. The criteria evaluated included time to radiographic union and any complications related to the procedure. Ancillary procedures included a gastrocnemius recession, tendo achilles lengthening and flexor digitorum longus tendon transfer. Radiographic evaluation was performed to determine time to bone graft incorporation.

Procedure

	An oblique incision is placed just distal to the sinus tarsi and 1-1.5 cm proximal to the calcaneocuboid joint. This approach usually avoids dorsal cutaneous nerves and will provide access to the lateral wall of the anterior calcaneus. Care should be taken in the preservation of the peroneal tendons and the sural nerve with.
	The osteotomy is performed approximately one cm proximal to the calcaneocuboid joint. An image intensifier can be used to confirm location prior to executing the periosteal incision and osteotomy. The periosteum is incised in a vertical fashion. An elevator is used to dissect enough periosteum from the lateral calcaneus in order to allow room for the sagittal saw. The sagittal saw blade is oriented perpendicular to the lateral surface of the calcaneus and perpendicular to the weight-bearing surface. An osteotome can be used to finish the osteotomy.
	A lamina spreader or mini distractor may be used to manipulate and distract the osteotomy to the desired position.

The authors typically use a freeze-dried or frozen allograft bone for distraction. The graft should be fashioned into a triangular or a trapezoid shape with the base lateral. The graft is then placed into the osteotomy site and tamped into position. The graft size is ranged from 7 - 10 mm in length proximal to distal. Fixation is generally not utilized due to the tight fit of the graft in the site.

Complications

Results

Cases

14 year old female with a painful flexible flatfoot treated with an anterior calcaneal osteotomy and lengthening with patellar allograft. Union is evident at 6 weeks post-op.

52 year old female with stage 2 posterior tibial tendon dysfunction who underwent a lateral column lengthening with freeze dried patellar allograft. Complete union seen at 10 weeks.

54 year old female who was treated with a lateral column lengthening with iliac crest allograft. The pre-operative and post-operative radiographs are shown for comparison.

Nonunion

Nonunion was a complication found in 3 of the adults who had the procedure performed and in none of the pediatric patients. One patient was asymptomatic after being treated non-operatively. One patient required revision of the nonunion with an iliac crest graft. Radiographic signs of union can be difficult to assess by conventional x-ray and may require advanced imaging such as a CT scan.

Discussion

Lateral column lengthening is a common procedure used for the correction of flexible juvenile and adult acquired flatfoot. Lateral column lengthening provides triplanar correction of hindfoot valgus and dorsolateral peritalar subluxation1,2,3. Opening wedge anterior calcaneal osteotomies were initially described for the treatment of flexible pediatric pes planovalgus and has now been well documented for use in reconstruction of the adult acquired flatfoot4. Tricortical bone graft is ideal for this procedure to obtain structural stability. Autogenous bone from the iliac crest is a common site to harvest this graft and is widely used. However, the use of allograft bone with this procedure has fewer reports. Mosca et al. utilized tricortical iliac crest allograft in 24 of 31 patients with no complications reported5. Dolan et al. prospectively compared iliac crest autograft to allograft for correction of the adult acquired flatfoot and found union rates to be equal between the two groups6. Myerson et al. reported successful union in 11 feet with an average time to union of 10 weeks when allograft bone was utilized7. The benefits of using allograft include less morbidity, less operative time and cost. Disease transmission has been of some concern with the use of allograft but the documented risk of transmission is very low.

Several complications have been reported related to the Evans procedure such as calcanealcuboid arthrosis, dorsal displacement of the anterior fragment, sural neuritis and stress fracture of the 5th metatarsal8. Complications specific to the graft include displacement, structural failure, nonunion or delayed union.

The average time to graft incorporation in our study was 10 weeks for adults and 9 weeks for pediatric patients. The pediatric patients had a 100% union rate. The adult populations had a 94% union rate. There were 2 patients that did not have complete graft incorporation at the time of final follow-up. One patient was asymptomatic with a CT scan showed partial bridging across the graft site. The other patient required revision with iliac crest autograft. Other complications included calcaneocuboid capsulitis, sinus tarsitis, sural neuritis and lateral column pain. The patient with sural neuritis required a sural neurectomy. All other symptoms were minor and resolved with conservative treatment. There were no other minor complications in the pediatric patients undergoing this procedure.

Our findings of union were comparable to those of prior studies. Our findings suggest that lateral column lengthening with allograft can be performed with a low number of complications and a successful union rate. The adult patient population had a higher number of minor complications. Most of these complications were related to symptoms of the lateral column which resolved with conservative means and did not relate directly to the use of allogenic bone graft.

The use of allograft for an opening wedge anterior calcaneal osteotomy is a safe procedure in the adult and pediatric population. We conclude from our results that there are fewer complications in pediatric patients and a time to union which is comparable to adults. To our knowledge there are no other published studies which compared outcomes, union rates and complications between adult and pediatric patients when utilizing allogenic bone grafts.

References

1. Anderson, AF; Fowler, SB: Anterior calcaneal osteotomy for symptomatic juvenile pes planus. Foot Ankle 4:274-283, 1984.
2. Evans, D: Calcaneo-valgus deformity. J. Bone Joint Surg. 57-B:270-278, 1975.
3. Sangeorzan, BJ; Mosca V; Hansen S. Effect of calcaneal lengthening on relationships among the hindfoot, midfoot, and forefoot. Foot Ankle 14:136-141.
4. Pomeroy, GC; Manoli, A: A new operative approach for flatfoot secondary to posterior tibial tendon insufficiency: a preliminary report. Foot Ankle Int. 18:206-212, 1997.
5. Mosca, VS: Calcaneal lengthening for valgus deformity of the hindfoot. Results in children who had severe, symptomatic flatfoot and skewfoot. J. Bone Joint Surg. 77-A:500-512, 1995.
6. Dolan, CM; Henning, JA; Anderson, JG; Bohay, Donald; Kornmesser, Marc. Randomized prospective study comparing tri-cortical iliac crest autograft to allograft in lateral column lengthening component for operative correction of adult acquired flatfoot deformity. Foot Ankle Int 28:8-12, 2007.
7. Myerson, MS; Neufeld, SK; Uribe, J: Fresh Frozen structural allografts in the foot and ankle. J. Bone J Surg. 87-A:113-120, 2005.
8. Davitt, JS; Morgan JM: Stress fracture of the 5th metatarsal after Evan's calcaneal osteotomy: a report of two cases. Foot Ankle Int 19:710-712, 1998.

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