BACKGROUND
Bone graft, whether cortical, cancellous, or cortico-cancellous, has many applications in foot and ankle surgery. Most commonly, it is used to fill osseous defects or enhance healing after surgery (1, 2). Bone grafts may be classified as either autograft, allograft, xenograft, or substitute material. Autograft continues to be the preferred choice due of its ability to develop mesenchymal cells into bone- and cartilage-forming cells, build pro- lattice for osteoblasts and other support cells, and induce osteoprogenitor cells into new cells for bone production(1, 3). However, the advantages of autogenous bone graft can sometimes be outweighed by problems, such as donor site pain and morbidity, increased blood loss, and cost of graft harvest (3). Allograft has been shown to be advantageous in its ability to provide structural support for deformity correction of deformities without complications of autogenous bone graft (4-6). However, allograft bone graft materials tend to incorporate at a slower rate, have ability to induce an immune response, and techniques of preservation may affect the mechanical properties (7). Bone graft substitutes incorporate properties of the autogenous and allogenic bone graft, via proprietary methods of merging different compounds into one material (3). This case report demonstrates the effectiveness of OsteoCure™ bone graft wedges in the reconstructive surgery of the foot and ankle.
CASE #1
A 56-year old female with a history of progressive right foot hallux valgus unresponsive to conservative care presents for surgical evaluation. Pre-operative physical exam reveals a painful right 1st MTP joint with dorsiflexion to 25 degrees and plantarflexion of 5 degrees, with hypermobility of the 1st ray. Additionally, there was heavy callous formation present submetatarsals 2 and 3, indicating overload in this area. The patient elected to undergo surgical correction via a Scarf bunionectomy and Cotton osteotomy, in order to correct the hallux valgus and reduce hypermobility the 1st ray. The surgical technique for the cotton osteotomy is described below, with pre-operative, 6-week, and 3-month radiographs shown (Image #1-3, respectively) An intraoperative photograph is shown in Image #4.
A linear incision was made overlying the 1st metatarsal base-cuneiform area of the right foot. The extensor tendon was retracted and utilizing a small bone saw, an osteotomy was made from dorsal to plantar approximately 7 mm behind the articular cartilage. The osteotomy was made approximately 80% through and then completed with a large osteotome. A 5mm/5° OsteoCure™ wedge was placed into the osteotomy and then tamped into position, without placement of fixation. Standard operative protocol for closure of the wound was subsequently followed.
The patient was placed in a non-weightbearing below knee cast for 3 weeks, followed by partial weightbearing in a CAM walker and physical therapy for an additional 3 weeks. Radiographs show maintained alignment and resorption of the graft at the final postoperative period. Patient denied any complications or infections following the procedure.
RESULTS
A 36-year old male presented with progressive pain in his arch of his left foot for some time that has gotten progressively worse in the last 6 months. The patient had failed conservative treatment in the form of orthotics, medrol dose pack, and anti-inflammatory medication. On clinical exam, the patient had a decreased arch height, forefoot abduction, and heel valgus present in the left foot when compared to the right foot. Patient ROM of the ankle joint was limited with a tight Achilles tendon. Patient had pain present along the course of the posterior tibial tendon. Additionally, he displayed weakness on single- and double-heel raise test and plantarflexion/inversion of the left foot. Computerized Gait analysis using E-MED pedobarograph/pressure plate (Novel Gmbh; Munich Germany) revealed left arch is abnormally loading; increased pressure to the left hallux, heel and right metatarsal head 2-4and hallux; left forefoot with minimal load; left heel is loading more than right. An MRI was conducted which showed complete rupture of the posterior tibial tendon 2cm distal to the medial malleolus. the patient elected to undergo surgical correction via a percutaneous tendo Achilles lengthening, Calcaneal Scarf osteotomy , Cobb tendon transfer, , and Cotton osteotomy, . The surgical technique for the Calcaneal Scarf is described below, with pre-operative, 6-week, and 3-month radiographs shown (Image #5-7) An intraoperative photograph is shown in Image #8.
The superior edge and inferior aspect of the calcaneus were identified. Utilizing an osteotomy guide, a Z-type osteotomy was made in the calcaneus, The posterior vertical limb was directed at a 45 degree angle from lateral to medial approximately 1.5 cm anterior to the posterior superior tuberosity which extended 15 mm. The transverse cut was directed anterior and plantar ward to an area 3 cm proximal to the calcaneal cuboid joint. A distal vertical osteotomy directed at a 45 degree angle was made from the junction of the horizontal osteotomy to the plantar aspect of the calcaneus at this level. An osteotome is used to complete all three cuts through the lateral wall. The calcaneus was translated 10mm laterally. A smooth laminar spreader was opened at the posterior vertical limb in order to elongated the calcaneus. The distal portion of the vertical osteotomy measured 11 mm in length, and a 10mm/10° OsteoCure™ wedge was placed in the defect. The laminar spreader was then removed from the superior aspect and a similar bone graft was inserted superiorly under compression and tamped into place. An 8.0mm cannulated screw was used to fixate the osteotomy under fluoroscopy. The protruding medial wall was tamped and compressed in place.
The patient was placed in a non-weightbearing below knee cast for 5 weeks, followed by partial weightbearing in a CAM walker and physical therapy for an additional 10 weeks. Radiographs, which were taken along the postoperative course, showed alignment of the osteotomies remained while the bone graft underwent full resorption of the graft at 4 months postoperatively. Patient denied any complications or infections following the procedure.
DISCUSSION AND CONCLUSION
Bone graft is often used to augment the course of healing in reconstructive surgery of the foot and ankle. While autogenous bone graft is the most commonly used, it tends to have a high rate of complications associated with its use and there is a limited quantity available for harvest. Allografts are useful, but have a slower incorporation rate, risk of infection and delayed union. Tissue-engineered bone graft substitutes have been developed that possess both autogenous and allograft properties, without any of their associated complications. OsteoCure™ bone graft substitute consists of polyglycolic acid (PGA) fibers, pores, surfactant, calcium sulfate, and polylactide-co-glycolide. Poylactide-co-glycolide has shown to be effective in adhesion of osteoblasts cells, calcium sulfate encourages bone growth. (8, 9), and PGA provides strength to the graft material. In conclusion, Osteocure™ is a safe and effective bone graft alternative in foot and ankle reconstruction.
BIBLIOGRAPHY
1. Mahan KT: “Bone Grafting,� in Comprehensive Textbook of Foot Surgery, 2nd Ed, Vol 2, ed by ED McGlamry, AS Banks, MS Downey, p 1232, Williams & Wilkins, Baltimore, 1992.
2. Donley BG, Richardson EG: Bone grafting in foot surgery, Foot Ankle Int. 1996 Apr 17(4): 242
3. Sammarco VJ, Chang L: Modern issues in bone graft substitutes and advances in bone tissue technology. Foot Ankle Clin N Am 2002 7: 19-41
4. Catanzariti A, Karlock L: The application of allograft bone in foot and ankle surgery. J Foot Ankle Surg. 1996; 35: 440-51.
5. Myerson MS, Neufield SK, Uribe J: Fresh-frozen structural allografts in foot and ankle. J Bone Joint Surg Am 2005; 87: 113-120.
6. Myerson MS, Schon LC, McGuigan FX, Oznur A. Result of arthrodesis of the hallux metatarsophalangeal joint using bone graft for restoration of length. Foot Ankle Int. 2000; 21:297-306
7. Khan SN, Cammisa FP Jr, Sandhu HS, Diwan AD, Girardi FP, Lane JM The biology of bone grafting J Am Acad Orthop Surg. 2005 Jan-Feb; 13(1):77-86.
8. Boone DW Complications of iliac crest graft and bone grafting alternatives in foot and ankle surgery. Foot Ankle Clin N Am 2003; 8:1-14.
T9. oro DR, Betti V, Spampinato S. Biocompatibility and integrin-mediated adhesion of human osteoblasts to poly (DL-lactide-co-glycolide) copolymers. Eur J Pharm Sci. 2004 Feb; 21(2-3):161-9
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