Transverse tibial bone transport for non-healing heel wound: A case report.

INTRODUCTION: Treatment of diabetic foot ulcer is complex and expensive, and frequently results in amputation. Transverse Tibia Transport is a new strategy for diabetic foot ulcers, which is based on the techniques of distraction histogenesis. PRESENTATION OF CASE: We present a 32-year-old male with longstanding insulin-dependent diabetes mellitus and many medical comorbidities with a non-healing heel ulcer of greater than 1 year. Following diagnosis of his diabetic foot ulcer complicated by osteomyelitis, he underwent a series of vascular and local wound interventions unsuccessfully. Transverse tibia transport was successful in healing the ulcer after 4 months. No complications were observed during follow up. DISCUSSION: Distraction histogenesis mechanically stimulates regeneration of soft tissues such as muscles, tendons, and blood vessels by sustained tension. Inducing vascular regeneration at a targeted site has broad potential value for treating various disorders such as atrophic union and osteomyelitis. CONCLUSION: For patients with refractory diabetic foot ulcers, transverse tibia transport may be considered as a treatment option.

Reverse Dynamization Accelerates Regenerate Bone Formation and Remodeling in a Goat Distraction Osteogenesis Model.

UPDATE: This article was updated on December 20, 2023, because of previous errors, which were discovered after the preliminary version of the article was posted online. Figure 4 has been replaced with a figure that presents different p values. Also, on page 1943, the text that had read: "Quantitative microCT confirmed that the total volume of the regenerate in the RD group was much smaller compared with the SF (p = 0.06) and DF (p = 0.007) groups, although it was significantly smaller only compared with the DF group (Fig. 4-A). The total volume of the intact bone (contralateral tibia) was significantly smaller in the RD group compared with the other groups, but the RD group had values closest to those for the intact tibia. Similarly, the RD group had less bone volume compared with the SF and DF groups, and this value was significantly different from the DF group (p = 0.034; Fig. 4-B). Of the 3 groups, the RD group had vBMD that was the closest to that of intact bone. It also had significantly higher vBMD compared with the SF and DF groups (p < 0.0001 for both; Fig. 4-C).The results of torsional testing (Fig. 4-D) confirmed that the regenerate bone formed under conditions of RD was significantly stronger than that formed under SF or DF (p < 0.001 versus SF group, and p = 0.0493 versus DF group)."now reads: "Quantitative microCT confirmed that the total volume of the regenerate in the RD group was significantly smaller compared with the SF and DF groups (p < 0.01 for both groups; Fig. 4-A). The total volume of the intact bone (contralateral tibia) was significantly smaller compared with the SF and DF groups (p < 0.0001 for both). The RD group had values closest to those for the intact tibia, and this difference was not significant (Fig. 4-A). Similarly, the RD group had less bone volume compared with the SF and DF groups, and this value was significantly different from the DF group (p < 0.01; Fig. 4-B). Of the 3 groups, the RD group had vBMD that was the closest to that of intact bone, but the intact bone was significantly different compared with all of the other groups (p < 0.0001 for all groups). The RD group had significantly higher vBMD compared with the SF and DF groups (p = 0.042 and p = 0.046, respectively; Fig. 4-C).The results of torsional testing (Fig. 4-D) confirmed that the regenerate bone formed under conditions of RD was significantly stronger than that formed under SF or DF (p < 0.0001 versus SF group, and p = 0.0493 versus DF group). The intact group was significantly different compared with the SF group (p < 0.0001)."

The concept of reverse dynamization involves modifying the mechanical environment surrounding a fracture to influence the healing response. Initially, less rigid stabilization is performed to allow micromotion, encouraging cartilaginous callus formation. This is followed by a conversion to more rigid fixation to prevent the disruption of neovascularization, thereby accelerating bone healing and remodeling. The effect of reverse dynamization in distraction osteogenesis has not been studied, to our knowledge. The aim of this study was to determine whether reverse dynamization can accelerate the formation and maturation of regenerate bone in a goat distraction osteogenesis model. Midshaft tibial osteotomies were created in 18 goats and stabilized using circular external fixation. After a 5-day latency period, 4 weeks of limb distraction began to obtain a 2-cm gap; this was followed by 8 weeks of regenerate consolidation. The goats were divided into 3 groups: static (rigid) fixation (SF, n = 6); dynamic fixation (DF, n = 6), consisting of continuous micromotion using dynamizers; and reverse dynamization (RD, n = 6), consisting of initial micromotion during the distraction period using dynamizers followed by rigid fixation during the consolidation period. Healing was assessed using radiographs, micro-computed tomography, histological analysis, and mechanical testing. Radiographic evaluation showed earlier regenerate formation in the DF and RD groups compared with the SF group. After the distraction and consolidation periods were completed, the regenerate formed under the conditions of RD had less trabeculation, higher bone mineral density, and smaller total and bone volumes, and were stronger in torsion compared with the SF and DF groups. This appearance is characteristic of advanced remodeling, returning closest to the values of intact bone. The DF group also had evidence of an interzone (radiolucent fibrous zone) at the end of the consolidation period. Application of the reverse dynamization regimen during distraction osteogenesis accelerated formation, maturation, and remodeling of regenerate bone. The findings of this study have important implications in the clinical setting, as reverse dynamization may lead to shorter treatment times and potentially lower prevalence of complications for patients needing distraction osteogenesis.

Narrative review of ring fixator management of recurrent club foot deformity.

Despite the widespread use of the Ponseti method for treatment of clubfeet, there continue to be a significant number of patients who present with a severe, stiff clubfoot as a result of extensive intra-articular soft tissue release or lack of access to care. In such patients, circular external fixators can be utilized for deformity correction with distraction across soft tissues, joints, and osteotomies. Ilizarov or hexapod circular fixators may be utilized according to surgeon preference. Indications for soft tissue release and osteotomies to aid in correction of clubfoot deformity with Ilizarov and hexapod fixators are not standardized and are guided by patient age, joint congruity, soft tissue suppleness, and osseous deformity. Correction time varies according to clubfoot deformity severity. Following deformity correction, external fixators are left in place for several weeks to stabilize the soft tissues and allow for osteotomy healing. Complications range from relatively minor pin tract infections that resolve with oral antibiotics to tarsal tunnel syndrome, osteomyelitis, or disabling arthritis requiring revision procedures. At Scottish Rite Hospital for Children, we prefer to correct severe residual clubfoot deformity with a hexapod external fixator. Acute correction and gradual correction via distraction are considered for each segmental deformity and utilized to efficiently correct deformity while minimizing soft tissue trauma. The purpose of this article is to summarize the relevant literature related to circular external fixator treatment of recurrent clubfoot deformity and outline our approach to the segmental deformities of the foot and ankle in this patient population.

Comparative Stiffness Characteristics of Ilizarov- and Hexapod-type External Frame Constructs.

BACKGROUND: The Ilizarov method and fixator are clinically recognised for the treatment of fractures, limb salvage and deformity correction. There have been extensive studies determining the basic mechanism for fracture healing using this technique. It is generally accepted that circular frames optimise the mechanical environment by reducing shear strain across the fracture while maintaining axial micromotion so as to promote fracture healing. There have been several new hexapod-type frames introduced into the market over the past 20 years with little comparative research into their biomechanical properties and resultant effects on the fracture environment. QUESTIONS/PURPOSES: To investigate the biomechanical behaviours of the TrueLok-Hex (TL-HEX) and Taylor spatial frame (TSF) hexapod-type circular external fixators with comparison to traditional Ilizarov-type (TL-Ilizarov and TSF-Ilizarov) constructs and potential performance in vivo. METHODS: Testing was performed on standardised four-ring TSF and TL-HEX constructs matched by identical frames using Ilizarov threaded rod constructs for each set of components. All frames were tested under physiological levels of axial, bending and torsional loading. Load-deformation properties for each construct under each mode of loading were calculated and analysed statistically using ANOVA. RESULTS: Under axial loading, the Ilizarov construct utilising TL-HEX components demonstrated the greatest rigidity followed by the Ilizarov construct using TSF components. Under bending loads, the difference in rigidity between constructs was similar but less marked. Under torsional loading, both hexapod frames were seen to be significantly more rigid than the Ilizarov constructs. Overall deformation around neutral loading was much higher in the TSF frame due to an observed significant "toe-in" laxity in the strut universal joints. The remaining deformation of both hexapod frames was similar with a higher level of TL-HEX rigidity in axial loading and a higher level of TSF rigidity in bending and torsion. CONCLUSION: In conclusion, both hexapod frame constructs were less rigid under axial loading but more rigid under bending and torsional loads than their comparative Ilizarov constructs. As a result of their Cardan universal joints, the TSF demonstrated greater overall planar strain due to the observed "toe-in" laxity around neutral loading while the TL-HEX, with ball-and-socket universal joints, demonstrated a minimal level of laxity. Beyond the initial deformation due to the preloaded laxity, both hexapod frames responded to loading in a similar manner. There were significant differences in the frames' mechanical behaviour under different loading conditions but further research is required to determine whether these translate in vivo into clinical significance. HOW TO CITE THIS ARTICLE: Fenton C, Henderson D, Samchukov M, et al. Comparative Stiffness Characteristics of Ilizarov- and Hexapod-type External Frame Constructs. Strategies Trauma Limb Reconstr 2021;16(3):138-143.

Reverse Dynamization Accelerates Bone-Healing in a Large-Animal Osteotomy Model.

BACKGROUND: Reverse dynamization is a mechanical manipulation regimen designed to accelerate bone-healing and remodeling. It is based on the hypothesis that a fracture that is initially stabilized less rigidly allows micromotion to encourage initial cartilaginous callus formation. Once substantial callus has formed, the stabilization should then be converted to a rigid configuration to prevent the disruption of neovascularization. The aim of the present study was to investigate whether bone-healing can be accelerated using a regimen of reverse dynamization in a large-animal osteotomy model. METHODS: Transverse 2-mm tibial osteotomies were created in 18 goats, stabilized using circular external fixation, and divided into groups of 6 goats each: static fixation (rigid fixation), dynamic fixation (continuous micromotion using dynamizers), and reverse dynamization (initial micromotion using dynamizers followed by rigid fixation at 3 weeks postoperatively). Healing was assessed with the use of radiographs, micro-computed tomography, and mechanical testing. RESULTS: Radiographic evaluation showed earlier and more robust callus formation in the dynamic fixation and reverse dynamization groups compared with the static fixation group. After 8 weeks of treatment, the reverse dynamization group had reduced callus size, less bone volume, higher bone mineral density, and no evidence of radiolucent lines compared with the static fixation and dynamic fixation groups. This appearance is characteristic of advanced remodeling, returning closest to the values of intact bone. Moreover, the tibiae in the reverse dynamization group were significantly stronger in torsion compared with those in the static fixation and dynamic fixation groups. CONCLUSIONS: These findings confirmed that tibial osteotomies under reverse dynamization healed faster, healed objectively better, and were considerably stronger, all suggesting an accelerated healing and remodeling process. CLINICAL RELEVANCE: This study demonstrates that the concept of reverse dynamization challenges the current understanding regarding the optimal fixation stability necessary to maximize the regenerative capacity of bone-healing. When reverse dynamization is employed in the clinical setting, it may be able to improve the treatment of fractures by reducing the time to union and potentially lowering the risk of delayed union and nonunion.

Staged Reconstruction for Type IV Tibial Deficiency (Distal Tibiofibular Diastasis): A Report of 2 Cases.

CASE: Congenital tibiofibular diastasis is a relatively rare form of limb deficiency, characterized by distal tibial tapering, absent ankle mortise, equinovarus foot deformity, and variable lower leg shortening. Treatment described has ranged from various forms of foot centralization with or without leg lengthening to amputation. We describe 2 cases treated in childhood by staged foot centralization by soft-tissue distraction, distal tibiotalar fusion, tibial lengthening, and subsequent limb length discrepancy equalization. At skeletal maturity, both patients ambulated independently without aid. CONCLUSIONS: Staged reconstruction with foot centralization and distal tibiotalar fusion is an option for carefully selected patients with tibiofibular diastasis who refuse foot ablation.

Real-Time Monitoring with a Controlled Advancement Drill May Decrease Plunge Depth.

BACKGROUND: Although drill use is fundamental to orthopaedic surgery, the risk of plunging past the far cortex and potentially damaging the surrounding soft tissues remains unavoidable with conventional drilling methods. A dual motor drill may decrease that risk by providing controlled drill-bit advancement and real-time monitoring of depth and energy expenditure. We hypothesized that using the dual motor drill would decrease plunge depth regardless of the user's level of experience. METHODS: Sixty-six subjects of varying operative experience (20 attending orthopaedic surgeons, 20 orthopaedic surgery residents, and 26 senior medical students) drilled 3 holes with a conventional drill and 3 holes with a dual motor drill in a bicortical Sawbones block set in ballistic gel. The depth of drill penetration into the ballistic gel was measured for each hole using a digital caliper. RESULTS: Overall, subjects plunged less with the dual motor drill (0.9 mm) than with the conventional drill (4.2 mm) (p < 0.001). This finding was consistent within each group: attending surgeons (0.9 compared with 3.2 mm; p = 0.02), residents (1.0 compared with 3.0 mm; p < 0.001), and students (0.7 compared with 6.0 mm; p < 0.001). Plunge depths were also stratified into 3 categories: 0 to <2 mm, 2 to 5 mm, and >5 mm. Using the dual motor drill, subjects were more likely to plunge <2 mm (97% plunged, on average, 0 to <2 mm and 3% plunged, on average, 2 to 5 mm), whereas subjects were more likely to plunge deeper with the conventional drill (27% plunged, on average, 0 to <2 mm, 45% plunged, on average, 2 to 5 mm, and 27% plunged, on average, >5 mm). Notably, no subject plunged ≥2 mm on the third attempt with the dual motor drill. Attending surgeons (p = 0.02) and residents (p = 0.01) plunged less than students with the conventional drill. There was no significant difference between attending surgeons and residents with the conventional drill (p = 0.96). There was no significant difference in plunge depth between groups using the dual motor drill. CONCLUSIONS: The dual motor drill significantly decreased plunge depth for both surgically experienced and inexperienced subjects. Although inexperienced subjects performed worse with the conventional drill than those with experience, there was no difference in their performance with the dual motor drill. CLINICAL RELEVANCE: Use of a controlled advancement drill may decrease the chance of plunge-related neurovascular injury during in vivo drilling.

Treatment Strategies and Frame Configurations in the Management of Foot and Ankle Deformities.

To provide standardized nomenclature for various hexapod frame configurations for foot and ankle deformity correction, a unique classification of the hexapod external fixators was proposed. This classification is based on number of correction levels, secured anatomic blocks, and direction of the strut attachment. It allows the combination of all different foot and ankle frame assemblies into a few standard hexapod configurations, irrespective of which external fixator is used.

Biomechanical Considerations in Foot and Ankle Circular External Fixation: Maintenance of Wire Tension.

Initial tensioning of the forefoot wires to 130 kg followed by simultaneous tensioning of the calcaneal wires to 90 kg and using the rigid double-row foot plate closed anteriorly via threaded rods produce maximum preservation of the initial wire tension during foot circular external fixation.

The Nature of Foot Ray Deficiency in Congenital Fibular Deficiency.

BACKGROUND: Absent lateral osseous structures in congenital fibular deficiency, including the distal femur and fibula, have led some authors to refer to the nature of foot ray deficiency as "lateral" as well. Others have suggested that the ray deficiency is in the central portion of the midfoot and forefoot.We sought to determine whether cuboid preservation and/or cuneiform deficiency in the feet of patients with congenital fibular deficiency implied that the ray deficiency is central rather than lateral in patients with congenital fibular deficiency. METHODS: We identified all patients with a clinical morphologic diagnosis of congenital fibular deficiency at our institution over a 15-year period. We reviewed the records and radiographs of patients who had radiographs of the feet to allow determination of the number of metatarsals, the presence or absence of a cuboid or calcaneocuboid fusion, the number of cuneiforms present (if possible), and any other osseous abnormalities of the foot. We excluded patients with 5-rayed feet, those who had not had radiographs of the feet, or whose radiographs were not adequate to allow accurate assessment of these radiographic features. We defined the characteristic "lateral (fifth) ray present" if there was a well-developed cuboid or calcaneocuboid coalition with which the lateral-most preserved metatarsal articulated. RESULTS: Twenty-six patients with 28 affected feet met radiographic criteria for inclusion in the study. All affected feet had a well-developed cuboid or calcaneocuboid coalition. The lateral-most ray of 25 patients with 26 affected feet articulated with the cuboid or calcaneocuboid coalition. One patient with bilateral fibular deficiency had bilateral partially deficient cuboids, and the lateral-most metatarsal articulated with the medial remnant of the deformed cuboids. Twenty-one of 28 feet with visible cuneiforms had 2 or 1 cuneiform. CONCLUSIONS: Although the embryology and pathogenesis of congenital fibular deficiency remain unknown, based on the radiographic features of the feet in this study, congenital fibular deficiency should not be viewed as a global "lateral lower-limb deficiency" nor the foot ray deficiency as "lateral." LEVEL OF EVIDENCE: Level IV-prognostic study.

The Management of Soft Tissue and Bone Loss in Type IIIB and IIIC Pediatric Open Tibia Fractures.

PURPOSE: Type III B and C open tibia fractures in children pose a challenge to the orthopaedic surgeon. Limb salvage is the initial goal for the majority of patients, but managing soft-tissue defects and bone loss can be a challenge. The purpose of this study was to evaluate the use of circular external fixation in the management of these injuries. METHODS: In this retrospective review, we examined children with type IIIB and IIIC open tibial fractures treated with circular external fixation and soft-tissue coverage between 1990 and 2010. Chart review included: mechanism and severity of injury, degree of bone and soft-tissue loss, technique and duration of external fixation, additional procedures, clinical and radiographic outcomes, and complications. RESULTS: Eight patients were identified whose average age at the time of injury was 10.4 years (range, 3.8 to 15.3 y). There were 7 type IIIB and 1 type IIIC fractures. All patients received free or rotational soft-tissue flaps. Average bone loss was 5.4 cm (range, 0 to 12 cm). Three techniques of circular external fixation were used, including: (1) static stabilization to allow for soft-tissue coverage and fracture healing, (2) acute shortening with plan for later limb lengthening, and (3) stabilization of the extremity for soft-tissue coverage and intended bone transport. Seven of 8 limbs were salvaged. Of those 7, all were followed to skeletal maturity and ambulating without assistive devices at final follow-up. Three patients had a clinically relevant leg-length discrepancy (≥2 cm). Four of 8 patients required secondary or contralateral procedures. CONCLUSIONS: Pediatric type IIIB and IIIC tibia fractures are limb-threatening injuries that require dynamic thinking and management as the bone and soft-tissue injuries evolve. We have proposed a general algorithm to guide the treatment of these severe injuries. In our experience, circular external fixation, in conjunction with this algorithm, provides the appropriate stability and environment for managing soft tissue and bone loss and can facilitate limb salvage. LEVEL OF EVIDENCE: Level IV.

Lengthening in Congenital Femoral Deficiency: A Comparison of Circular External Fixation and a Motorized Intramedullary Nail.

BACKGROUND: Circular external fixation for limb-lengthening is associated with frequent and numerous complications. Intramedullary lengthening devices represent a potential advance in limb-lengthening. The purpose of this study was to compare the outcomes of femoral lengthening in pediatric patients treated by either circular external fixation or a motorized intramedullary nail. METHODS: All patients with a diagnosis of congenital femoral deficiency who had undergone femoral lengthening with either circular external fixation or a motorized intramedullary nail were identified. The motorized intramedullary nail (FITBONE) was used with approval of the U.S. Food and Drug Administration on an individual compassionate-use basis. RESULTS: Fourteen skeletally mature patients underwent fourteen femoral lengthening sessions using circular external fixation, and thirteen patients underwent fifteen lengthening sessions using the motorized nail. The amount lengthened was similar, with a mean of 4.8 cm (range, 1.0 to 7.4 cm) in the circular fixation group and 4.4 cm (range, 1.5 to 7.0 cm) in the motorized nail group. Complications occurred in all lengthening sessions in all fourteen patients managed with the circular external fixation and in 73% of fifteen lengthening sessions in the thirteen patients managed with the motorized nail. The circular external fixation group averaged 2.36 complications per lengthening session compared with 1.2 per session in the motorized nail group. Twenty-nine percent of the circular fixation group failed to achieve a lengthening goal of at least 4 cm compared with 27% of the motorized nail group who failed to reach the goal. Eight patients had undergone eleven femoral lengthening sessions with circular external fixation prior to undergoing ten lengthening sessions by motorized nail. These patients had a comparable rate of complications with both types of lengthening, but the total number of complications averaged 2.6 per lengthening session with circular external fixation compared with 1.6 per lengthening session with the motorized nail. CONCLUSIONS: A decreased number of complications was noted with use of a motorized intramedullary nail compared with circular external fixation in pediatric patients undergoing femoral lengthening for congenital femoral deficiency. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Clinical Implications of Psychosocial Factors on Pediatric External Fixation Treatment and Recommendations.

BACKGROUND: Pediatric limb reconstruction using circular external fixation is a prolonged treatment that interrupts patients' daily function. Patient personality characteristics and expectations may interfere with planned treatment, making complicated medical procedures more challenging. The aims of this study are to identify factors impacting treatment outcome and recommendations for preoperative evaluation and planning. QUESTIONS/PURPOSES: (1) Are there group differences between patients with and without a preexisting mental health condition(s) in terms of unplanned reoperations? (2) Does the number of surgical procedures before current external fixator placement correlate with the number of unplanned readmissions, unplanned reoperations, and days spent in circular external fixation? (3) Are there group differences between single- compared with two-parent households in terms of inpatient narcotic doses, length of inpatient stay, number of unplanned readmissions, length of readmission(s), and/or unplanned outpatient clinic visits? (4) Does patient age at the time of surgery have an impact on treatment duration, postoperative complications, and treatment outcome? METHODS: This is a retrospective chart review of pediatric patients who underwent limb reconstruction between 2008 and 2012. Patients with limb length discrepancy > 4 cm or severe angular deformity and who agreed to intervention were treated with circular external fixation. Sixty-seven patients were included; 16 patients were excluded. Statistical analyses included Pearson r correlation and t-test. RESULTS: Patients who reported preexisting mental health diagnosis (13%) had more unplanned reoperations than patients who did not (no mental health diagnosis; 87%) (mental health diagnosis 3.4 ± 10.3 versus no mental health diagnosis 0.2 ± 0.5 reoperation[s], p = 0.022). Number of previous surgical procedures correlated with number of unplanned reoperations (r = 0.448, p < 0.001), number of unplanned readmissions (r = 0.375, p < 0.001), and number of days in an apparatus (r = 0.275, p = 0.018). Compared with patients from two-parent households, patients from single-parent households received a greater number of inpatient narcotic doses (single-parent 129 ± 118 versus two-parent 73 ± 109 doses, p = 0.039), longer length of inpatient stay (single-parent 73 ± 63 versus two-parent 40 ± 65 days, p = 0.036), more unplanned readmissions (single-parent 0.4 ± 0.1 versus two-parent 0.2 ± 0.2 readmission, p = 0.024), longer hospitalization when readmitted (single-parent 5 ± 11 versus two-parent 1 ± 3 day(s), p = 0.025), and fewer unplanned outpatient visits (single-parent 0.2 ± 0.8 versus two-parent 0.9 ± 1.1 visit, p = 0.005). Apparatus applications with successful outcome had higher average age than those with poor outcome (successful outcome 16 ± 3 versus poor outcome 13 ± 4 years old, p = 0.011). Age at time of apparatus application correlated with number of prescribed antibiotics (r = 0.245, p = 0.036) and number of days in an apparatus (r = 0.233, p = 0.047). CONCLUSIONS: As a result of the inherent challenges of limb reconstruction, surgical candidates should be preoperatively assessed and mitigating psychosocial factors managed to maximize successful treatment outcome. LEVEL OF EVIDENCE: Level IV, therapeutic study.

Deformity correction in pediatric skeletal dysplasia: treatment challenges and solutions.

We reviewed our experience with limb-deformity correction in 54 children with skeletal dysplasias. Our goal was to outline common treatment strategies developed in our hospital to overcome the challenges associated with the management of these conditions. Utilization of computer-assisted preoperative planning, intraoperative monitoring of peripheral nerve function, individualized bone segment stabilization using a modular circular external fixation system, and a flexible distraction protocol improved the precision of angular deformity correction in our practice, simplified external fixator assembly, diminished postoperative frame modifications, enhanced the stability of fixation, and reduced the rate of complications.

Evaluation of complications of treatment of severe Blount's disease by circular external fixation using a novel classification scheme.

Corrective osteotomy for recalcitrant varus deformity secondary to adolescent and infantile Blount's disease can be challenging because of a combination of severity of deformity, complexity of deformity, and frequent association with patient obesity. We present here the outcome of treatment by osteotomy and gradual deformity correction by circular external fixation in 31 patients with either infantile or adolescent Blount's disease. We used a unique classification scheme to quantify and qualify complications in this patient group: category I, complications not requiring an alteration in the treatment plan, not involving unplanned return to surgery, and not influencing outcome; category II, complications requiring an alteration in the treatment plan, including unplanned returns to surgery, but that did not influence outcome; category IIIA, complications that resulted in a failure to achieve treatment goals; and category IIIB, complications that resulted in a failure to achieve treatment goals and the development of a new pathology or worsening of patient condition. All but one patient in this group incurred at least one complication. However, despite the complex nature of this patient population, 88% achieved satisfactory correction without developing category IIIA or IIIB complications. Careful selection of patients and vigilant postoperative management can result in excellent outcomes with circular external fixation and gradual correction in this challenging patient population.

Treatment of femoral lengthening-related knee stiffness with a novel quadricepsplasty.

BACKGROUND: Knee stiffness is common after femoral lengthening. Certain patients require a quadricepsplasty when therapy does not improve flexion. A small subset of such patients may also have obligate patellar dislocation with knee flexion due to contracture of the extensor mechanism. We describe our surgical approach for both clinical situations and our outcomes in a pediatric population. METHODS: Six patients, 2 with obligate patellar dislocation, were reviewed (9% of our femoral lengthening population). Indications for surgery included persistent symptomatic restriction of flexion after at least 3 months of therapy or obligate lateral patellar dislocation with knee flexion. Knee range of motion and clinical strength were assessed. Four patients were available for gait analysis and concentric quadriceps strength testing by isokinetic dynamometer. Patient satisfaction was surveyed by questionnaire. RESULTS: All patients had full flexion before lengthening. The mean length gained (by circular external fixation and/or intramedullary motorized nail) was 10.7 cm. The mean age at the time of quadricepsplasty was 16 years. The average active flexion preoperatively was only 48 degrees. Two patients with obligate patellar dislocation and relatively good knee flexion inflated the average preoperative knee flexion. Although both had knee flexion to 100 degrees, the patella dislocated with flexion beyond 30 degrees. At follow-up (mean, 6.2 y) active flexion averaged 120 degrees (P<0.004). All patients had 5/5 clinical strength and no significant quadriceps lag. No patients had patellar instability postoperatively. Isokinetic dynamometer revealed an average weakness of 63% compared with the nonoperative quadriceps. Gait analysis indicated patients had near-normal gait patterns. All patients were satisfied and would pursue the same treatment. CONCLUSIONS: Our quadricepsplasty can significantly increase knee flexion and treat obligate patellar dislocation in the setting of extension contracture after femoral lengthening when nonoperative measures fail. LEVEL OF EVIDENCE: Level IV.

Citric acid-derived in situ crosslinkable biodegradable polymers for cell delivery.

Herein, we report a first citric acid (CA)-derived in situ crosslinkable biodegradable polymer, poly(ethylene glycol) maleate citrate (PEGMC). The synthesis of PEGMC could be carried out via a one-pot polycondensation reaction without using organic solvents or catalysts. PEGMC could be in situ crosslinked into elastomeric PPEGMC hydrogels. The performance of hydrogels in terms of swelling, degradation, and mechanical properties were highly dependent on the molar ratio of monomers, crosslinker concentration, and crosslinking mechanism used in the synthesis process. Cyclic conditioning tests showed that PPEGMC hydrogels could be compressed up to 75% strain without permanent deformation and with negligible hysteresis. Water-soluble PEGMC demonstrated excellent cytocompatibilty in vitro. The degradation products of PPEGMC also showed minimal cytotoxicity in vitro. Animal studies in rats clearly demonstrated the excellent injectability of PEGMC and degradability of the in situ-formed PPEGMC. PPEGMC elicited minimal inflammation in the early stages post-injection and was completely degraded within 30 days in rats. In conclusion, the development of CA-derived injectable biodegradable PEGMC presents numerous opportunities for material innovation and offers excellent candidate materials for in situ tissue engineering and drug delivery applications.

The role of variable muscle adaptation to limb lengthening in the development of joint contractures: an experimental study in the goat.

Muscle stiffness and joint contractures are currently regarded as the most common complications of limb lengthening. To better understand the mechanisms of joint contractures, architectural changes of all involved muscles were analyzed in 9 goats after 20% tibial lengthening with standard distraction protocol.All 13 muscles of the goat's tibia were found to be organized into an anterior compartment with 2 longitudinal and 4 pennate muscles and a posterior compartment with 1 longitudinal and 6 pennate muscles. Longitudinal muscles showed better compliance to distraction than pinnate muscles. Although muscle-to-bone lengthening ratio ranged widely (0-1.2), most of the muscles and especially those located in the posterior compartment showed much less lengthening than the bone. Muscular portions of the muscles lengthened more substantially (average, 17%) than their associated tendons (average, 7%). Muscle fiber length changes varied greatly between muscles (range, 0%-88%). Normalization of muscle fiber length revealed considerable elongation of anterior muscles fibers (25%) that was associated with an addition of new sarcomeres in series. Fiber length increase of all posterior muscles but one occurred by stretching of existing sarcomeres, with little addition or even dissolution of sarcomeres in series. This correlated with muscle mass changes showing significant muscle atrophy in the posterior compartment and better mass preservation in the anterior compartment.The study revealed striking difference in response to limb lengthening between individual muscles and muscles from antagonistic compartments in particular. Poor sarcomerogenesis in the posterior muscles leading to their insufficient length increase seems to play major role in the development of joint contractures.

Changes in pennate muscle architecture after gradual tibial lengthening in goats.

The purpose of this investigation was to examine the changes in unipennate muscle architecture after distraction osteogenesis. Nine adult goats underwent 20% tibial lengthening in one of the hind limbs. Immediately after distraction, lengthened and contralateral (untreated) tibialis caudalis (TC) muscles were harvested. Lengths of the muscle belly, muscle fiber (FL), sarcomere (SL), tendon (TL), and superficial aponeurosis, as well as muscle mass, pennation angle (PA), and physiological cross-sectional area (PCSA), were compared between the treated and contralateral sides. Lengthened TC muscle demonstrated 20.8% increase in belly length, 4.39% increase in TL, and 36.7% increase in FL, while PA decreased by 37.2% (P = 008). Muscle length increase was mainly due to lengthening of muscle belly, which resulted both from FL increase and 15.3% length increase in the aponeurosis component of muscle belly, without significant effect of the PA decrease. The FL increase was due to SL increase, not to sarcomere neogenesis, while mass and PCSA did not change. We concluded that although muscle architecture can be adversely affected by distraction because of deficient sarcomere neogenesis, PCSA can remain unchanged, giving false impression of preserved function. Change in PA plays only minimal role in muscle adaptation to distraction.

Semi-automated intra-operative fluoroscopy guidance for osteotomy and external-fixator.

This paper outlines a semi-automated intra-operative fluoroscopy guidance and monitoring approach for osteotomy and external-fixator application in orthopedic surgery. Intra-operative Guidance module is one component of the "LegPerfect Suite" developed for assisting the surgical correction of lower extremity angular deformity. The Intra-operative Guidance module utilizes information from the preoperative surgical planning module as a guideline to overlay (register) its bone outline semi-automatically with the bone edge from the real-time fluoroscopic C-Arm X-Ray image in the operating room. In the registration process, scaling factor is obtained automatically through matching a fiducial template in the fluoroscopic image and a marker in the module. A triangle metal plate, placed on the operating table is used as fiducial template. The area of template image within the viewing area of the fluoroscopy machine is obtained by the image processing techniques such as edge detection and Hough transformation to extract the template from other objects in the fluoroscopy image. The area of fiducial template from fluoroscopic image is then compared with the area of the marker from the planning so as to obtain the scaling factor. After the scaling factor is obtained, the user can use simple operations by mouse to shift and rotate the preoperative planning to overlay the bone outline from planning with the bone edge from fluoroscopy image. In this way osteotomy levels and external fixator positioning on the limb can guided by the computerized preoperative plan.