Ex Vivo Preservation of Ovine Periosteum Using a Perfusion Bioreactor System.

Periosteum is a highly vascularized membrane lining the surface of bones. It plays essential roles in bone repair following injury and reconstruction following invasive surgeries. To broaden the use of periosteum, including for augmenting in vitro bone engineering and/or in vivo bone repair, we have developed an ex vivo perfusion bioreactor system to maintain the cellular viability and metabolism of surgically resected periosteal flaps. Each specimen was placed in a 3D printed bioreactor connected to a peristaltic pump designed for the optimal flow rates of tissue perfusate. Nutrients and oxygen were perfused via the periosteal arteries to mimic physiological conditions. Biochemical assays and histological staining indicate component cell viability after perfusion for almost 4 weeks. Our work provides the proof-of-concept of ex vivo periosteum perfusion for long-term tissue preservation, paving the way for innovative bone engineering approaches that use autotransplanted periosteum to enhance in vivo bone repair.

Biosynthesized Bandages Carrying Magnesium Oxide Nanoparticles Induce Cortical Bone Formation by Modulating Endogenous Periosteal Cells.

Bone grafting is frequently conducted to treat bone defects caused by trauma and tumor removal, yet with significant medical and socioeconomic burdens. Space-occupying bone substitutes remain challenging in the control of osteointegration, and meanwhile activation of endogenous periosteal cells by using non-space-occupying implants to promote new bone formation becomes another therapeutic strategy. Here, we fabricated a magnesium-based artificial bandage with optimal micropatterns for activating periosteum-associated biomineralization. Collagen was self-assembled on the surface of magnesium oxide nanoparticles embedded electrospun fibrous membranes as a hierarchical bandage structure to facilitate the integration with periosteum in situ. After the implantation on the surface of cortical bone in vivo, magnesium ions were released to generate a pro-osteogenic immune microenvironment by activating the endogenous periosteal macrophages into M2 phenotype and, meanwhile, promote blood vessel formation and neurite outgrowth. In a cortical bone defect model, magnesium-based artificial bandage guided the surrounding newly formed bone tissue to cover the defected area. Taken together, our study suggests that the strategy of stimulating bone formation can be achieved with magnesium delivery to periosteum in situ and the proposed periosteal bandages act as a bioactive media for accelerating bone healing.

Congenital pseudarthrosis of the tibia: Rate of and time to bone union following contralateral vascularized periosteal tibial graft transplantation.

INTRODUCTION: Congenital pseudarthrosis of the tibia (CPT) is one of the most challenging orthopedic disorders. The use of a vascularized tibial periosteal grafts has been recently reported as a powerful tool to obtain bone union. We report its use in CPT. PATIENTS AND METHODS: Retrospective short-term study of 29 children (18 male/11 female, 15 right-sided/14 left-sided) of mean age 45 months (range 11-144 months), operated upon after October 2014. Nonunion site was debrided, and the periosteum of the involved limb was excised. A vascularized tibial periosteal graft (mean length 10.7 cm (range 9-15 cm) with a monitoring skin island (mean length 4.1 cm (range 3-5 cm) and based on the anterior tibial vessels, was obtained from the contralateral tibia. Anterior tibial vessels were always the recipient vessels. Most cases were stabilized with an LCP plate. The rate of and time to bone union were analyzed. Charts only were evaluated through the first 3 months after bone union was achieved. RESULTS: The flap survived and bone union was obtained in all cases, through a periosteal callus, in a mean time of 5.1 weeks (range 3-6 weeks). Mean follow-up was 8.3 months (range 7-19 months). No union failures occurred 3 months after resuming unprotected weight bearing. CONCLUSIONS: Our novel technique produced a consistent, rapid capacity for CPT union, superior to previously-reported techniques. However, it cannot be recommended as a standard method of treatment until consistent, long-term, refracture-free follow-up is documented.

Osteogenic Capacity of the Prefabricated Periosteofascial Flap using Vascular Induction with Skeletonized Pedicle Transfer in Rabbit Calvarium.

The study investigated the osteogenic capacity of a prefabricated periosteal flap created using only skeletonized pedicle transfer without fascia or muscle for vascular induction in rabbit calvarium. A critical-sized bone defect was made in the parietal bone centered on the sagittal suture, and the demineralized bone matrix was implanted. The periosteofascia over the defect was used as a form of prefabricated periosteofascial flap (PPF group, N=10), conventional periosteofascial flap (CPF group, N=10), and nonvascularized free periosteofascial graft (FPG group, N=6). The prefabricated flap was designed via vascular induction by transferring the central artery and vein of the right auricle onto the periosteofascia for 4 weeks prior to flap elevation. A quantitative comparison of volume restoration and radiodensity in the bone defect and a histological study were performed after 6 weeks of covering the bone defect with periosteofascia. The volume restoration of the bone defect covered with the PPF (43.4%) was not different from that of the CPF (46.2%), but significantly increased compared with that of the FPG (24.6%). The radiodensity of the bone defect covered with the PPF (-186.3 HU) was not different from that of the CPF (-153.6 HU), but significantly increased compared with that of the FPG (-329.8 HU). The results were based on adequate vascular development of the periosteum and were closely related to the osteogenic changes in the implanted demineralized bone matrix (DBM). In conclusion, even in the PPF created by transferring only skeletonized vascular pedicles, the osteogenic capacity of the periosteofascial flap is well maintained.

Repair of long bone defects of large size using a tissue-engineered periosteum in a rabbit model.

Tissue engineering is a promising approach for bone regeneration. In this study, we aimed to investigate whether tissue engineered periosteum (TEP), which was fabricated by combining osteogenically-induced mesenchymal stem cells (MSCs) with porcine small intestinal submucosa (SIS), could restore long bone defects of large size in rabbits. Twenty-four adult New Zealand white rabbits (NZWRs) were used in the experiments. Long bone defects of large size (30 mm-50 mm; average, 40 mm) were established on both sides of NZWRs' radii. The defects were treated with TEP (Group A), allogeneic deproteinized bone (DPB, Group B), TEP combined with DPB (Group C), and pure SIS (Group D). The healing outcome was evaluated by radiography and histological examination at 4, 8, and 12 weeks post-treatment. The radiographical findings showed that bone defects of large size were all repaired in Groups A, B and C within 12 weeks, whereas Group D (pure SIS group) failed to result in defect healing at 4, 8, and 12 weeks. Although there was some new bone regeneration connecting the allografts and bone ends, as observed under radiographical and histological observations, bone defects of large sizes were restored primarily by structurally allografted DPB within 12 weeks. The TEP groups (Groups A and C) showed partial or total bone regeneration upon histological inspection. Based on 12-week histological examinations, significantly more bone was formed in Group A than Group C (P < 0.05), and both groups formed significantly more bone than in Groups B and D. The results indicated that long bone defects of a large size could be restored by TEP or TEP combined with the DPB scaffold, and such materials provide an alternative approach to resolving pathological bone defects in clinical settings.

Septal Perforation Repair Using Bilateral Rotational Flaps With Interposed Mastoid Periosteal Graft.

OBJECTIVES/HYPOTHESIS: To evaluate the outcomes of endonasal repair of septal perforations utilizing opposing bilateral rotational flaps and a periosteum interposition graft. METHODS: Retrospective review of a single surgeon, tertiary referral center experience of patients who underwent septal perforation repair. Patient demographics, etiology of perforation, closure rate, and complication data were obtained. Patients screening positively for cocaine use or anti-neutrophil cytoplasmic antibodies (ANCA) were not offered repair. RESULTS: A total of 104 patients were included, 65 male and 39 female with mean age of 45.4 years. Etiology of perforations included prior surgery in 45, trauma in 15, and unknown in 44, and the average perforation size in each etiologic group were 1.35 cm, 1.25 cm, and 1.30 cm, respectively. The greatest dimension of perforations repaired ranged from 0.5 cm to 1.5 cm. The overall success rate was 87.5% at 6 month follow-up. Successful closure was achieved in 95.6%, 86.7%, and 79.5%, respectively (χ2  = 5.264, P = .0218). CONCLUSION: Our described technique is a reliable endonasal approach with predictable outcomes in septal perforations up to 1.5 cm in size. Having an unknown etiology of septal perforation may be a risk factor for failure. LEVEL OF EVIDENCE: 4 Laryngoscope, 131:1497-1500, 2021.

Extensor Retinaculum Flap and Fibular Periosteum Ligamentoplasty After Failed Surgery for Chronic Lateral Ankle Instability.

BACKGROUND: The anterior talofibular ligament and the calcaneofibular ligament are 2 of the most frequently injured structures in sports, being damaged in 30% to 45% of all sports injuries. Most reconstructive procedures are successful but can deteriorate with time and can lead to low-grade radiographic degeneration. METHODS: We operated on 26 consecutive patients from 2001 to 2008 who had failed previous surgical procedures for the lateral ligamentous complex of the ankle, with an average of 104 (range, 75-140) months. RESULTS: The overall functional rating was excellent in 14 ankles, good in 10, fair in 1, and poor in 1. Twenty-four patients (92.3%) were satisfied with the procedure and 15 (57.7%) were able to return to their preinjury level of activity. Local complications were detected in 2 patients who presented with skin necrosis; 1 patient developed severe reflex sympathetic dystrophy. CONCLUSION: Revision surgery for the management of failure after surgical treatment of chronic lateral ankle instability is under debate, and the literature is devoid of clinical studies with long-term follow-up. The technique described offers a high rate of long-term excellent and good results, with a low rate of complications and a good rate of return to preinjury level. LEVEL OF EVIDENCE: Level IV, retrospective case series.

Prospective Long-term Follow-up of Autologous Chondrocyte Implantation With Periosteum Versus Matrix-Associated Autologous Chondrocyte Implantation: A Randomized Clinical Trial.

BACKGROUND: Matrix-associated autologous chondrocyte implantation (MACI) is a further development of the original autologous chondrocyte implantation periosteal flap technique (ACI-P) for the treatment of articular cartilage defects. PURPOSE: We aimed to establish whether MACI or ACI-P provides superior long-term outcomes in terms of patient satisfaction, clinical assessment, and magnetic resonance imaging (MRI) evaluation. STUDY DESIGN: Randomized controlled trial; Level of evidence, 2. METHODS: A total of 21 patients with cartilage defects at the femoral condyle were randomized to MACI (n = 11) or ACI-P (n = 10) between the years 2004 and 2006. Patients were assessed for subjective International Knee Documentation Committee (IKDC) score, Lysholm and Gillquist score, Tegner Activity Score, and 36-Item Short Form Health Survey (SF-36) preoperatively (T0), at 1 and 2 years postoperatively (T1, T2), and at the final follow-up 8 to 11 years after surgery (T3). Onset of osteoarthritis was determined using the Kellgren-Lawrence score and Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score, and delayed gadolinium-enhanced MRI of cartilage was used to evaluate the cartilage. Adverse events were recorded to assess safety. RESULTS: There were 16 patients (MACI, n = 9; ACI-P, n = 7) who were reassessed on average 9.6 years after surgery (76% follow-up rate). The Lysholm and Gillquist score improved in both groups after surgery and remained elevated but reached statistical significance only in ACI-P at T1 and T2. IKDC scores increased significantly at all postoperative evaluation time points in ACI-P. In MACI, IKDC scores showed a significant increase at T1 and T3 when compared with T0. In the majority of the patients (10/16; MACI, 5/9; ACI-P, 5/7) a complete defect filling was present at the final follow-up as shown by the MOCART score, and 1 patient in the ACI-P group displayed hypertrophy of the repair tissue, which represents 6% of the whole study group and 14.3% of the ACI-P group. Besides higher SF-36 vitality scores in ACI-P at T3, no significant differences were seen in clinical scores and MRI scores between the 2 methods at any time point. Revision rate was 33.3% in MACI and 28.6% in ACI-P at the last follow-up. CONCLUSION: Our long-term results suggest that first- and third-generation ACI methods are equally effective treatments for isolated full-thickness cartilage defects of the knee. With the number of participants available, no significant difference was noted between MACI and ACI-P at any time point. Interpretation of our data has to be performed with caution due to the small sample size, which was further limited by a loss to follow-up of 24%.

Free vascularized medial femoral condyle corticoperiosteal flap with non-vascularized iliac crest graft for the treatment of recalcitrant clavicle non-union.

Clavicle non-union is a challenging problem. Open reduction with internal fixation and autologous bone grafting is usually the first line treatment. In case of failure, the medial femoral condyle corticoperiosteal flap in association with a non-vascularized bone graft is one of the therapeutic options, which is well adapted to the clavicle anatomical characteristics. We performed a retrospective study of all patients treated with this technique in our department. Between 2014 and 2017, five patients with recalcitrant post traumatic clavicle non-unions received this surgical treatment. The average nonunion time period was 50.2 month (range 10 to 108 months), and the mean defect length was 3.4 cm (between 2 and 5 cm), defects were all located in the medial third of the clavicle Three patients achieved full consolidation with an average time of consolidation of 8,7 months (range 6 to12 months). Patients with radiological consolidation had better functional improvement and pain reduction with an average DASH score improved from 53,6 before surgery to 19,6 after consolidation (at the last follow up visit). There was one donor site complications (hematoma). The medial femoral condyle corticoperiosteal flap with non-vascularized iliac crest graft is a good option for the management of recalcitrant clavicle non-union, especially when the bone defect is small.

Effects of low-intensity pulsed ultrasound exposure on rats tibia periosteum.

The periosteum is a rich source of osteoprogenitor cells and periosteal grafts can be used as an alternative method to replace bone grafts. The low-intensity pulsed ultrasound (LIPUS) has often been used as a noninvasive method to stimulate osteogenesis and reduce the fracture healing time. The aim of this study was to evaluate the effects of the ultrasound exposure on the rat tibia periosteum. Group I (7 animals) received LIPUS therapy on the left tibia for 7 days and group II (7 animals) on the left tibia for 14 days. After euthanasia, the tibias were processed. Number of periosteal cells and vessels and thickness of the periosteum were analyzed. The number of periosteal cells was higher in stimulated periosteum compared to controls at 7 and 14 days, but the number of vessels and the thickness only were higher in the group stimulated at 14 days. Furthermore, the ultrasound treatment for 14 days was more effective than 7 days. The ultrasound stimulation of the periosteum prior to grafting procedure can be advantageous, since it increases periosteal activity, and LIPUS may be an alternative method for stimulating the periosteum when the use of periosteal grafts in bone repair is needed.

The medial femoral condyle free corticoperiosteal flap versus traditional bone graft for treatment of nonunions of long bones: a retrospective comparative cohort study.

Fracture healing is a complex process and many factors change the local biology of the fracture and reduce the physiologic repair process. Since 1991 the free vascularised corticoperiosteal graft has been proposed to treat nonunions. In this study we compare the healing rate and the healing time of the free vascularised corticoperiosteal graft harvested from medial femoral condyle versus the traditional cancellous bone graft from the iliac crest combined with other biologic or pharmacologic factors. We performed a retrospective cohort study. The main measures of outcomes were the rate of bone union and the mean healing time from surgery. The authors performed 10 free vascularised corticoperiosteal grafts in the cohort A and 10 patients received traditional cancellous bone graft plus other biologic or pharmacologic treatment in the same period in the cohort B. The mean follow up in cohort A was 18.6 months with a healing rate of 100% (10/10). In cohort B the mean follow up was 22.5 month with a healing rate of 90%. The mean time to obtain union (healing time) in the group that was treated with the free flap procedure was significantly shorter, 3.2 months versus a mean time of 8.8 months in the other group. Some studies describe a high healing rate of recalcitrant nonunions with treatments different from vascularized bone flaps: it is difficult to compare the results of vascularized bone transfers with the results of other case series. Our groups are very homogeneous even if it is difficult to define correct inclusion criteria because there is still no agreement about what is defined a recalcitrant or difficult nonunion, and the number of trials of previous surgery before to perform a vascularized free flap. Even if our study cohort is small, we have demonstrated that the MFCCF generally seems to give a better healing chance with a shorter healing time compared to other treatments.

Lower eyelid reconstruction with pericranium graft and Mustarde flap. / Reconstrucción de párpado inferior mediante injerto de pericráneo y colgajo de Mustardé.

We report the case of a 68-year-old man with a left lower eyelid basal cell carcinoma with squamous differentiation. Resection was performed under frozen section technique and the defect (inner canthus, two thirds of the lower eyelid and 2.5cm of the cheek) reconstructed 2 days after surgery in a single surgical operation: posterior lamella with pericranial graft and anterior lamella with Mustarde flap. After one year of follow-up, the patient has an adequate appearance, good eyelid support and position, vascularized tissue like the native eyelid and no tumor recurrence.

Floppy eyelid syndrome "plasty" procedure: Employment of a periosteal transposition flap for surgery of floppy eyelid syndrome.

IMPORTANCE: Floppy eyelid syndrome "plasty" (FESplasty) is a surgical technique that addresses underlying superior tarsal plate and lateral canthal instability in floppy eyelid syndrome (FES) and aims to restore normal anatomical and physiological function to the upper eyelid. BACKGROUND: To describe the use of FESplasty in the surgical management of FES, and to report outcomes in an initial patient cohort. DESIGN: Retrospective study. PARTICIPANTS: Seven patients (nine eyelids) with FES undergoing FESplasty. METHODS: A single surgeon (G.W.) performed all procedures. FESplasty utilizes a periosteal flap based at the inferolateral orbital rim, and applied to the anterior surface of the upper tarsal plate. It is combined with a titrated shortening procedure of the upper eyelid. Patient demographics, comorbidities and ocular symptoms and signs were recorded preoperatively. Pre- and postoperative upper eyelid distractibility were graded and documented. MAIN OUTCOME MEASURES: Postoperative improvement in upper eyelid distractibility and symptomatology, operative complications and FES recurrence. RESULTS: FES symptoms and upper eyelid laxity improved at last follow-up (average 24 weeks) in all patients, with no FES recurrences after a maximum follow-up of 36 weeks. One patient, in whom FESplasty exacerbated his pre-existing aponeurotic ptosis, required definitive ptosis surgery subsequently. There was one case of postoperative wound infection. Obstructive sleep apnoea was present in four of the seven patients. The remaining three patients were awaiting assessment. CONCLUSIONS AND RELEVANCE: FESplasty is likely to confer long-term effective stabilization of the lateral canthal tendon, lateral commissure and superior tarsal plate. Anatomical and functional results appeared to have been successfully achieved.

Use of Mastoid Periosteum Graft in Primary and Revision Rhinoplasty.

BACKGROUND: The authors initiated the use of a mastoid periosteum graft to augment or camouflage the dorsum and radix. This report describes the techniques and treatment outcomes of mastoid periosteum grafts in primary and revision rhinoplasty. MATERIALS AND METHODS: Medical records of 62 patients who underwent rhinoplasty with mastoid periosteum were reviewed retrospectively. Of these, 21 patients who participated in follow-up for more than 6 months were analyzed through a comparison of pre- and postoperative photographs. Aesthetic results were scored on a scale of 0 to 4 (0 = poor, 1 = fair, 2 = moderate, 3 = good, 4 = excellent) with photographic evaluation by two independent surgeons. RESULTS: A mastoid periosteum graft was used in 32 primary and 30 revision cases. The graft was used to augment the radix (28 cases), dorsum (15 cases), and both radix and dorsum (19 cases). Cartilage underlay was combined with mastoid periosteum grafts in 38 patients (61.3%, 17 in radix graft, 8 in dorsal graft, and 13 in both). The aesthetic outcome score assessed in 21 patients was 2.8 on average (3.2 in primary and 2.4 in revision cases). Cartilage combined cases showed better aesthetic outcome than free graft cases (3.1 vs. 2.5, respectively). Three cases of partial graft resorption were found, but there were no major complications. CONCLUSIONS: Mastoid periosteum grafting is a safe and effective method to augment the radix or dorsum in primary and revision rhinoplasty. Long-term partial resorption cannot be completely excluded, which necessitates further study. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

The Full-Thickness Palatal Graft Technique: Description of an Original Surgical Technique and 15 Case Reports.

Gingival thickness plays a pivotal role in both the etiology and treatment of gingival recessions. When treating gingival recessions by different periodontal plastic surgery techniques, a relationship has been reported between the thickness of the tissue used to cover the exposed root surface and the recession reduction. This case series illustrates a technique making use of a very thick graft, which consists of the entire thickness of the palate in its central part, from the periosteum to the epithelium, to obtain complete root coverage with high predictability. At 12 months, the treatment resulted in 100.22% ± 6.95% root coverage, and 14 of the 15 treated teeth (93.3%) were completely covered.

Clinical and radiographical ten years long-term outcome of microfracture vs. autologous chondrocyte implantation: a matched-pair analysis.

PURPOSE: To compare the clinical and radiographical long-term outcome of microfracture (MFX) and first-generation periosteum-covered autologous chondrocyte implantation (ACI-P). METHODS: All subjects (n = 86) who had been treated with knee joint ACI-P or microfracture (n = 76) with a post-operative follow-up of at least ten years were selected. Clinical pre- and post-operative outcomes were analyzed by numeric analog scale (NAS) for pain, Lysholm, Tegner, IKDC, and KOOS score. Radiographical evaluation was visualized by magnetic resonance imaging (MRI). Assessment of the regenerate quality was performed by the magnetic resonance observation of cartilage repair tissue (MOCART) and modified knee osteoarthritis scoring system (mKOSS). Relaxation time (RT) of T2 maps enabled a microstructural cartilage analysis. RESULTS: MFX and ACI of 44 patients (24 females, 20 males; mean age 38.9 ± 12.1 years) resulted in a good long-term outcome with low pain scores and significant improved clinical scores. The final Lysholm and functional NAS scores were significantly higher in the MFX group (Lysholm: MFX 82 ± 15 vs. ACI-P 71 ± 18 p = 0.027; NAS function: MFX 8.1 ± 3.5 vs. ACI-P 6.0 ± 2.5; p = 0.003). The MOCART score did not show any qualitative differences. KOSS analysis demonstrated that cartilage repair of small defects resulted in a significant better outcome. T2-relaxation times were without difference between groups at the region of the regenerate tissue. CONCLUSION: This study did not demonstrate coherent statistical differences between both cartilage repair procedures. MFX might be superior in the treatment of small cartilage defects.

Vascularized Thumb Metacarpal Periosteal Flap for Scaphoid Nonunion in Adolescents: A Prospective Cohort Study of 12 Patients.

PURPOSE: To evaluate clinical and radiological outcomes after surgical treatment of scaphoid nonunion in adolescents with a vascularized thumb metacarpal periosteal pedicled flap (VTMPF). METHODS: Twelve patients younger than 18 years with scaphoid nonunion, who underwent a VTMPF procedure without bone grafting, were included for this prospective cohort study, at a mean follow-up of 10.2 months. Patients were operated on by 3 different hand surgeons at 3 hand surgery institutions. All patients received a VTMPF, but with different scaphoid internal fixation modalities, in 10 cases using 1 or 2 retrograde 2-mm headless compression screws and in 2 cases without internal fixation. RESULTS: In 11 boys and 1 girl, the mean age was 15.6 years. There were 1 type D1 nonunions (Herbert classification), 6 type D2, 2 type D3, and 2 type D4. Six patients had previously undergone an unsuccessful surgical attempt to treat their nonunion. The mean anterior bone defect was 3.5 mm in length. The patients experienced no postoperative complications. Successful consolidation was achieved in all cases, with 79% cross-sectional trabecular bridging at 12 weeks. Pain subsided after surgery and patients experienced improvements in both their Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH) and Modified Mayo Wrist Score (MMWS) results. Overall, 34% and 40% gains in strength and wrist motion, relative to the contralateral normal side, were observed. CONCLUSIONS: In this study, the use of VTMPF for scaphoid nonunion in children and adolescents is associated with generally good outcomes. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

The Role of Allograft Bone in Foot and Ankle Arthrodesis and High-Risk Fracture Management.

Allogenic bone graft has long been accepted as a standard of care in the surgical arthrodesis of the foot and ankle and treatment of certain high-risk, comminuted fracture types that have greater potential for delayed union or nonunion. It has been shown in multiple studies to be equivalent to autograft in regard to union rates without the morbidity associated with bone graft harvest. We present a retrospective study on the efficacy of an allogenic cancellous/periosteal cellular bone matrix with mesenchymal stem cells and angiogenic growth factors. The study includes a cohort of 41 procedures and 40 patients who underwent foot and ankle arthrodesis, fracture fixation, or a simultaneous combination of both. Radiographic consolidation of the fracture/fusion site was reviewed at regular intervals (first postoperative visit at 1 week and 4, 8, and 12 weeks and at regular intervals until healing was confirmed). Age, workmen's compensation insurance, diabetes, and nicotine use were evaluated as potential risk factors. Our retrospective study indicated that allograft bone has the potential to positively affect union rates in foot and ankle arthrodesis and certain high-risk fracture types that have potential for delayed union/nonunion. Levels of Evidence: Level IV.