Preservation of the foot in a five-year-old child with bilateral congenital deficiency of the tibia

Congenital tibial deficiency is a rare anomaly causing shortening and varus deformity of the lower extremity. Recent limb lengthening and foot repositioning techniques enable functional results with preservation of the foot. We present a five-year-old boy with bilateral congenital tibial deficiency of type 2 according to the Jones classification, who was treated with tibia-fibular fusion without Syme amputation. His ambulation depended on crawling. Radiographic examination showed a normally developed fibula with thickening in the distal portion, and only proximal tibia with absence of the distal part. He also had bilateral stiff equinovarus deformity. In a series of operations, he underwent bilateral tibia-fibular fusion and fibular osteotomy, subtalar arthrodesis and metatarsal osteotomy in the right foot, and subtalar arthrodesis in the left foot. At the end of a six-year treatment and follow-up, walking was achieved despite some degree of limping.     

Split tibialis posterior tendon transfer with concomitant distal tibial derotational osteotomy in children with cerebral palsy

Fifteen lower extremities with a spastic equinovarus foot deformity associated with internal tibial torsion were identified. Each lower extremity underwent a split tibialis posterior tendon transfer combined with a distal tibial derotational osteotomy. The medical record of each patient was reviewed retrospectively. We paid particular attention to clinic visits, gait analyses, and surgical procedures performed. These patients were followed up for an average of 4 years and 5 months after surgery. Twenty-seven percent had an excellent result, 13% developed a rigid equinovarus deformity, and 40% developed a severe planovalgus deformity. Eight of the 15 lower extremities required further corrective surgery because their resultant deformities limited their ambulation, was painful, or both. The combination of a split tibialis posterior tendon transfer with a distal tibial derotational osteotomy increases the difficulty of balancing the muscle forces across the spastic equinovarus foot, increasing the likelihood that overcorrection and a planovalgus deformity will develop.     

Reconstructive osteotomy of fibular malunion: review of the literature

The treatment of ankle fractures has a primary goal of restoring the full function of the injured extremity. Malunion of the fibula is the most common and most difficult ankle malunion to reconstruct. The most frequent malunions of the fibula are shortening and malrotation resulting in widening of the ankle mortise and talar instability, which may lead to posttraumatic osteoarthritis. The objective of this article is to review the literature concerning the results of osteotomies for correcting fibular malunions and to formulate recommendations for clinical practice. Based on available literature, corrective osteotomies for fibular malunion have good or excellent results in more than 75% of the patients. Reconstructive fibular osteotomy has been recommended to avoid or postpone sequela of posttraumatic degeneration, an ankle arthrodesis or supramalleolar osteotomy. The development of degenerative changes is not fully predictable; therefore, it is advisable to reconstruct a fibular malunion soon after the diagnosis is made and in presence of a good ankle function. Recommendations were made for future research because of the low level of evidence of available literature on reconstructive osteotomies of fibular malunions.     

Chipping corrective osteotomy for reconstruction of malunion with angular deformity of the lower extremity: Technical tips and preliminary clinical results

IntroductionSignificant functional disturbance, deformity, and malalignment may occasionally develop after healing of a fracture, especially one involving the lower extremities. This study sought to provide preliminary evidence of the effectiveness of chipping corrective osteotomy (CCO), which does not require autologous bone grafting, for treating malunion with lower extremity angular deformity.MethodsWe retrospectively reviewed clinical and radiologic results of 6 male patients (median age 48.5 years) treated with CCO for femoral and tibial malunion (4 femurs, 4 tibias) with angular deformity in the coronal plane. In performing CCO, we applied a temporary external fixator to correct the deformity; definitive fixation was performed using a locking plate. Time to consolidation after the surgery was recorded. The Mikulicz line was evaluated before surgery and at final follow-up in each patient to confirm a change in alignment of the affected lower extremity. We measured the score taken as the ratio of the distance between the medial tibial joint surface and the Mikulicz line to the width of the tibial plateau.ResultsMedian follow-up duration was 34 months. Bone healing was achieved by a median of 3.5 months postoperatively. Correction of the mechanical axis in the affected lower extremity was achieved in all 6 patients. Median score by the length from the tibial medial joint surface to the Mikulicz line to the tibial plateau width was 7.7% preoperatively and 25.7% at final follow-up.DiscussionThese preliminary findings suggest that CCO is potentially useful for treating malunion with lower extremity angular deformity.ConclusionFurther evaluation in a larger series is needed to clarify the usefulness of CCO in correction of angular malunion.     

Distal tibial osteotomies for the treatment of foot and ankle disorders.

Distal tibial osteotomy is an effective treatment for a variety of pediatric and adult foot and ankle disorders. Exposure osteotomies provide access to the tibiotalar joint for such problems as talar body fractures and osteochondral lesions of the talus. The channel osteotomy provides improved access to posterior talar dome lesions, especially for the use of osteochondral autograft. Although technically demanding, the supramalleolar osteotomy can benefit many patients, including patients with residual clubfoot deformity, primary and secondary osteoarthritis, malunion, and physeal arrest.     

Results of tibial rotational osteotomy without concomitant fibular osteotomy in children with cerebral palsy

A retrospective review was performed of 46 consecutive ambulatory children with cerebral palsy and tibial torsion who underwent 72 distal tibial derotational osteotomies without concomitant fibular osteotomy. The average amount of derotation measured at surgery was 21 +/- 5 degrees. The average change in thigh-foot angle at follow-up was 21 +/- 9 degrees. There were eight perioperative complications (11%): three delayed unions, three superficial wound dehiscences, one case of osteomyelitis, and one superficial pin tract infection. There were no incidences of malunion or nonunion. Preoperative and postoperative three-dimensional gait analysis data were used to determine the effect of distal tibial osteotomy on foot progression angle in seven subjects (11 limbs). Foot progression improved significantly. This study shows that distal tibial osteotomy alone (without concomitant fibular osteotomy) is an effective and safe procedure for correcting and maintaining correction of tibial torsion in patients with cerebral palsy.     

踝关节骨折畸形愈合的重建手术

目的 总结踝关节骨折畸形愈合重建术的临床疗效.方法 2006年1月至2009年1O月,共收治23例踝关节陈旧性骨折畸形愈合患者.男14例,女9例;平均年龄45岁(21～69岁).初次受伤至最终重建术平均间隔18个月(12～36个月),其中11例患者曾接受切开复位内固定术.术前常规行X线及CT检查,对畸形进行个体化评估:所有患者均有不同程度的腓骨短缩或旋转,合并内、外翻畸形者4例,下胫腓联合间隙增宽者5例.对所有腓骨短缩或旋转的患者行腓骨延长截骨术,内外翻畸形则行开放或闭合楔形截骨,而下胫腓增宽者则须行下胫腓功能性融合.术后定期行影像学随访评估骨愈合情况,记录并发症发生情况,并采用美国骨科足踝外科协会(American Orthopedic Foot Ankle Society,AOFAS)踝关节与后足功能评分来评估治疗效果.结果 共21例患者获随访,平均随访36个月(12～58个月).所有随访患者均无感染、内固定失败、骨不连、畸形复发等发生.影像学随访显示于术后平均12周(10～14周)骨愈合,且力线恢复良好.AOFAS踝关节与后足功能评分从术前平均28分(15～39分)改善为术后1年平均82分(70～94分).2例患者因严重创伤性关节炎分别于术后18个月和术后2年行踝关节融合术.结论 对于踝关节骨折畸形愈合的患者,通过早期重建手术恢复腓骨长度和旋转及踝穴的匹配,踝关节功能可获得极大的改善,也可延缓创伤性关节炎的发展.

Abstract：

Objective To summarize the clinical outcomes of reconstruction of malunited ankle fractures.Methods From January 2006 to October 2009,23 malunited ankle fractures were treated in our department.All deformities were evaluated individually based on pre-operatively X-ray and CT scan.Varying degrees of fibular shortening or rotational deformity were found in all patients,with 4 cases of varus or valgus deformity,and 5 of a widen syndesmosis.Then different reconstructive techniques were chosen according to the type of malunion:a lengthening fibular osteotomy was performed in patients with fibular shortening or rotational deformity;an opening or closing wedge osteotomy was chosen correspondingly in patients with varus or valgus deformity;functional fusion of syndesmosis was performed in cases of widen syndesmosis.The postoperative follow-up included standard radiography to evaluate bone union;relative complications were also recorded and functional outcome were assessed with American Orthopedic Foot Ankle Society (AOFAS)ankle-hindfoot scores.Results Twenty-one patients were followed up with an average period of 36 months (12-58 months).There were no complications of infection,implant failure,nonunion or malunion.Solid union with a favorable alignment was obtained at an average of 12 weeks (10-14 weeks).The mean pre-operative AOFAS ankle-hindfoot score was 28 (15-39).While the score increased to 82 (70-94) one year after operations.But 2 patients underwent ankle arthrodesis correspondingly 18 months and 24 months post-operatively due to severely post-traumatic arthritis.Conclusion An early realignment reconstruction of the length and rotation of fibula and the congruity of ankle mortise may improve the ankle function and slow down the development of post-traumatic arthritis for patients who suffered from malunited ankle fractures.     

Checkrein deformity due to extensor hallucis longus hypotrophy treated with extensor digitorum longus tendon transfer

Checkrein deformity is a relatively rare condition caused by hypotrophy or adhesion of a tendon after a lower leg injury. The occurrence of this condition due to the dysfunction of the extensor hallucis longus (EHL) is extremely rare. Only a few related case reports have been published, and Z-lengthening of the EHL tendon was performed for almost all patients.We report a case of checkrein deformity due to EHL hypotrophy. The patient was involved in a traffic accident 7 years ago. He sustained left tibial and fibular closed diaphyseal fractures and underwent minimally invasive plate osteosynthesis. He continued to have left great toe symptoms characterized by dorsiflexion of the great toe during ankle plantarflexion. The EHL had become an insufficient power source because of considerable hypotrophy. Therefore, a tendon transfer using the extensor digitorum longus to the second toe was performed as a primary treatment.     

Complications and outcomes of the transfibular approach for posterolateral fractures of the tibial plateau

ObjectiveEvaluate complication rates and functional outcomes of fibular neck osteotomy for posterolateral tibial plateau fractures.DesignRetrospective case series.SettingUniversity hospital.PatientsFrom January 2013 to October 2014, 11 patients underwent transfibular approach for posterolateral fractures of the tibial plateau and were enrolled in the study. All patients who underwent transfibular approach were invited the return to the hospital for another clinical and imaging evaluation.InterventionTransfibular approach (fibular neck osteotomy) with open reduction and internal fixation for posterolateral fractures of the tibial plateau.Main outcome measurementsComplications exclusively related to the transfibular approach: peroneal nerve palsy; knee instability; loss of reduction; nonunion and malunion of fibular osteotomy; and functional outcomes related to knee function.ResultsTwo patients failed to follow-up and were excluded from the study. Of the 9 patients included in the study, no patients demonstrated evidence of a peroneal nerve palsy. One patient presented loss of fracture reduction and fixation of the fibular neck osteotomy, requiring revision screw fixation. There were no malunions of the fibular osteotomy. None of the patients demonstrated clinically detectable posterolateral instability of the knee following surgery. American Knee Society Score was good in 7 patients (77.8%), fair in 1 (11.1%), and poor in 1 (11.1%). American Knee Society Score/Function showed 80 points average (60–100, S.D:11).ConclusionThe transfibular approach for posterolateral fractures is safe and useful for visualizing posterolateral articular injury. The surgeon must gently protect the peroneal nerve during the entire procedure and fix the osteotomy with long screws to prevent loss of reduction.Level of evidenceTherapeutic level IV.     

Fibular nonunion and equinovarus deformity secondary to posterior tibial tendon incarceration in the syndesmosis: a case report after a bimalleolar fracture-dislocation.

A 39-year-old woman sustained a grade II open bimalleolar fracture-dislocation of the left ankle. Six months after an ORIF of these fractures was performed, she presented with a nonunion of the distal fibula fracture and with a fixed hindfoot equinovarus and forefoot adduction deformity. At surgery for repair of the fibular nonunion, the posterior tibial tendon (PTT) was found to be entrapped in the posterior tibiotalar joint, with a portion of the tendon interposed between the tibia and the fibula in the area of the posterior syndesmosis. After extrication of the PTT, the hindfoot varus and forefoot adduction deformity were corrected. To our knowledge, this is the first case report in the English literature of a missed PTT syndesmotic entrapment that resulted in a fibular nonunion and in a fixed foot deformity after an open bimalleolar ankle fracture dislocation.     

Applications of ring fixators in complex foot and ankle trauma

There is a growing base of literature that supports the use of external ring fixators in the treatment of complex foot and ankle fractures. Clinical studies that determine definitively the optimal treatment for particular injuries are absent. Small wire ring fixators have a growing role in allowing the stabilization of complex skeletal injuries with a minimum of iatrogenic soft tissue injury. Ring fixators should be considered in the algorithm of treatment of complex lower extremity fractures with associated significant soft tissue injury. One of the cornerstones of trauma management is the preservation of reconstructive options after injury. As interest in ankle arthroplasty increases and experience broadens, such options may be available to patients who sustain severe tibial plafond or talus fractures. It is imperative that hindfoot alignment and height be maintained and infection avoided so that reconstructive osteotomy, arthrodesis, and arthroplasty remain as options for patients who sustain severe trauma.     

应用单边外固定支架矫正胫骨近端内翻畸形

目的 探讨应用单边外固定支架矫正胫骨近端内翻畸形的疗效.方法 2004年7月至2010年8月应用单边外固定支架治疗5例胫骨近端内翻畸形患者,男2例,女3例;年龄18～42岁,平均32岁.胫骨平台骨折与胫骨近端骨折畸形愈合各2例,胫骨近端截骨延长后出现牵开骨痂的畸形愈合1例.术中对腓骨进行截骨,在胫骨安装外固定支架,并在胫骨近端进行截骨.术后7～10 d通过外固定支架逐渐牵开并纠正成角畸形.结果 所有患者术后获5～11个月(平均8.4个月)随访.1例患者牵开处不愈合,经植骨治疗后愈合;其余4例均愈合,愈合时间为3～6个月,平均4.8个月,带架时间为4～8个月,平均6.8个月.所有腓骨截骨端均愈合,针道除并发轻微反应外无严重并发症,手术与矫正过程中未出现神经损伤等并发症.机械轴偏向矫正后较健侧平均外移8 mm(1～13mm).胫骨近端内侧角矫正后平均为90°(87°～92°).矫正后患侧肢体和健侧差异为-6～1 mm,胫骨和健侧长度差异为-2～3 mm.结论 单边外固定支架能够成功矫正胫骨近端内翻畸形愈合,与传统的外翻截骨内同定相比,它具有创伤小、无需植骨及截骨方法简单的优点,逐渐矫正能获得更准确的力线,同时可矫正肢体短缩、避免再次手术.

Abstract：

Objective To review gradual correction of proximal tibial varus malunion with a unilateral external fixator for osteogenetic distraction. Methods From July 2004 to August 2010, we treated 5 cases of proximal tibial varus malunion with a unilateral external fixator. They were 2 men and 3 women,with an average age of 32 years (from 18 to 42 years). Two cases were malunion after tibial plateau fracture,2 after proximal tibial fracture, and one after osteogenetic distraction. After fibular osteotomy, a tibial unilateral external fixator was installed before proximal tibial osteotomy. Varus was corrected for 7 to 10 days after surgery by gradual distraction till the same alignment was obtained as the contralateral side. The external fixator was not removed until consolidation and full weight bearing. Results The follow-ups ranged from 5 to 11 months (average, 8. 4 months). Four cases got united after 3 to 6 months (average, 4. 8 months).Time for external fixator ranged from 4 to 8 months (average, 6. 8 months) . One case obtained bone union after bone grafting. All fibulas healed after osteotomy. No other complications were present except mild pin-tract problems. Compared with the contralateral side, the corrected malalignment deviation was laterally displaced by 8 mm on average (from 1 to 13 mm), the corrected medial proximal tibial angle was 90° on average (from 87° to 92°), the limb length discrepancy was -6 to 1 mm, and the tibial length discrepancy was - 2 to 3 mm. Conclusions Proximal tibial varus malunion can be corrected gradually and effectively by a unilateral external fixator. Its advantages over valgus osteotomy and internal fixation are less invasion due to simple transverse osteotomy, accurate correction not only of angulation but also of length discrepancy, and no need of bone grafting or implant removal.     

Editorial Commentary: An Inverted V-Shaped High Tibial Osteotomy Combining a Lateral Closing Wedge and Medial Opening Wedge May Have Advantages

High tibial osteotomy (HTO) is enjoying somewhat of a resurgence as a treatment for medial compartment arthritis with a varus deformity. An inverted V-shaped high tibial osteotomy (IVHTO), which is essentially a combined lateral closing-wedge high tibial osteotomy (CWHTO) and medial opening-wedge high tibial osteotomy (OWHTO), has some theoretical benefits over more conventional techniques. This also has been termed a combined HTO or a hemi-wedge osteotomy. After valgus correction is performed, the osteotomy is fixed with the bone wedge resected from the lateral side being inserted into the medial side. There may be a clinical advantage of an IVHTO over a CWHTO, and retrospective evidence has shown some postoperative radiologic differences between the techniques, but there are some inconsistencies between the studies. Proponents have argued that an IVHTO can correct a severe varus deformity more easily than a CWHTO, and that an IVHTO will not change the posterior tibial slope, the patellar height, or the length of the lower limb because the hinge point is located at the centre of rotation of angulation of the lower limb deformity. However, there may be disadvantages of this technique, including the technical difficulty of performing a precise inverted V-shaped osteotomy and the need to perform a fibular osteotomy, with the associated risk of peroneal nerve injury. Prospective clinical and radiological studies are needed, particularly comparing an IVHTO with an OWHTO, to help decide where the hinge of an HTO should be placed: lateral, medial, or central. My view is that the argument for adopting the IVHTO technique over other techniques is not yet persuasive, particularly as the IVHTO is more technically demanding than an OWHTO, my current preferred technique.     

Fibular bowing due to tibial shortening in isolated fracture of the tibia: failure of late segmental fibulectomy to relieve ankle pain

Fracture of the tibia with an intact fibula is prone to delayed and nonunion or varus malunion and, as a complication of the latter, late arthrosis of the ankle joint. A less well-known type of malunion is tibial shortening with fibular bowing due to relative fibular lengthening. We present such a case with chronic ankle pain. Late segmental fibulectomy failed to improve the symptoms. We recommend primary segmental fibulectomy in all isolated fractures of the tibial shaft in adults and adolescents, in order to forestall the early and late complications.     

Fibular bowing due to tibial shortening in isolated fracture of the tibia: Failure of late segmental fibulectomy to relieve ankle pain

Summary Fracture of the tibia with an intact fibula is prone to delayed and nonunion or varus malunion and, as a complication of the latter, late arthrosis of the ankle joint. A less well-known type of malunion is tibial shortening with fibular bowing due to relative fibular lengthening. We present such a case with chronic ankle pain. Late segmental fibulectomy failed to improve the symptoms. We recommend primary segmental fibulectomy in all isolated fractures of the tibial shaft in adults and adolescents, in order to forestall the early and late complications.     

3D打印截骨导板辅助治疗胫骨骨折畸形愈合

目的探讨3D打印截骨导板在胫骨骨折畸形愈合截骨矫治术中的应用效果。方法回顾性分析2010年1月至2018年1月期间郑州大学第一附属医院骨科收治的30例胫骨骨折畸形愈合患者资料。根据治疗方法不同将患者分为2组:15例患者行3D打印截骨导板辅助截骨术治疗(3D打印组),男9例,女6例;年龄(46.3±8.2)岁;骨折畸形愈合位于胫骨中上段11例,胫骨下段4例;左侧6例,右侧9例;内翻畸形8例,外翻畸形7例;术前骨折畸形角度24.3°±5.5°。15例患者使用传统手术方法治疗(传统手术组),男10例,女5例;年龄(47.1±6.0)岁;骨折位于中上段12例,下段3例;左侧5例,右侧10例;内翻畸形7例,外翻畸形8例;术前骨折畸形愈合角度平均22.5°±5.4°。记录并比较两组患者术前一般资料、手术时间、术中出血量及术后下肢力线恢复情况。结果3D打印组和传统手术组胫骨骨折畸形愈合术前一般资料比较差异均无统计学意义(P>0.05),具有可比性。3D打印组和传统手术组患者术后平均随访12、10个月。3D打印组手术时间较传统手术组明显缩短[(102.2±13.0)vs.(137.9±10.5)min],术中出血量较传统手术组明显减少[(77.3±39.7)vs.(163.3±35.2)mL],术后3D打印组畸形角度较传统手术组显著减小[(1.9°±0.4°)vs.(3.2°±0.9°)],以上项目两组间比较差异均有统计学意义(P<0.05)。末次随访时两组均未见内固定物松动,截骨处均实现愈合,未再次出现畸形,下肢力线恢复良好。结论3D打印截骨导板技术在辅助胫骨骨折畸形愈合的截骨治疗中能精准截骨,减少手术时间及术中出血量,有效纠正下肢力线,术后近期疗效良好,是胫骨骨折畸形愈合有效的辅助技术。     

Surgical correction of bowlegs in achondroplasia

A retrospective review of 39 surgical procedures to correct bowlegs in achondroplasia was performed. Three operative procedures had been used sequentially over 27 years. Sixteen tibiae were treated by proximal closing wedge tibial osteotomy, proximal fibular epiphysiodesis and casts. Twelve tibiae were treated by opening wedge osteotomies using external fixation with no fibular shortening. Eleven tibiae were treated by the Ilizarov technique with 3-cm tibial lengthening, deformity correction, and distal translation of the proximal fibula. The Ilizarov technique is the most satisfactory method for correction of proximal bowlegs in early childhood. Distal tibial osteotomy and fibular shortening is recommended for correction of distal bow legs in older children.     

Reconstruction of a Complex Foot Injury With Free Remodeled Fibular Osteocutaneous Flap: A Case Report and Literature Review

Management of complex foot injuries, which involve open fractures and severe trauma to soft tissues, represent a challenge to orthopedic clinicians. In the present case report, we treated a complex foot injury with a remodeled fibular osteocutaneous free flap to reconstruct the anterior and lateral areas of the foot. The flap survived completely. At the 9-month follow-up examination, bony union of the graft bone was identified by radiographic examination. The reconstructed foot could bear body weight, and the patient could maintain a bipedal gait without discomfort. The remodeled fibular osteocutaneous free flap provides an option for functional reconstruction of foot defects.     

Physeal arrest about the knee associated with non-physeal fractures in the lower extremity

The cases of seven patients who had a physeal arrest about the knee in association with nonphyseal fractures in the lower extremity were reviewed. The patients were between ten and twelve and one-half years old at the time of injury, and the physeal arrest involved either the posterolateral part of the distal femoral physis or the anterior part of the proximal tibial physis. There was no evidence of iatrogenic trauma to the physis. Recognition of the physeal injury was delayed for an average of one year and ten months until a gross angular deformity appeared. Adolescents who have fractures of the lower extremities that do not appear to involve a physeal plate should nevertheless be evaluated and followed for possible physeal injury about the knee that can be detected only after additional growth has taken place.     

Optimal location for fibular osteotomy to provide maximal compression to the tibia in the management of delayed union and hypertrophic non-union of the tibia

BackgroundTibial shaft fractures are the commonest long bone fracture, with early weight-bearing improving the rate of bony union. However, an intact fibula can act as a strut that splints the tibial segments and holds them apart. A fibular osteotomy, in which a 2.5 cm length of fibula is removed, has been used to treat delayed and hypertrophic non-union by increasing axial tibial loading. However, there is no consensus on the optimal site for the partial fibulectomy.MethodsNine leg specimens were obtained from formalin-embalmed cadavers. Transverse mid-shaft tibial fractures were created using an oscillating saw. A rig was designed to compress the legs with an adjustable axial load and measure the force within the fracture site in order to ascertain load transmission through the tibia over a range of weights. After 2.5cm-long fibulectomies were performed at one of three levels on each specimen, load transmission through the tibia was re-assessed. A beam structure model of the intact leg was designed to explain the findings.ResultsWith an intact fibula, mean tibial loading at 34 kg was 15.52 ± 3.26 kg, increasing to 17.42 ± 4.13 kg after fibular osteotomy. This increase was only significant where the osteotomy was performed proximal to or at the level of the tibial fracture. Modelling midshaft tibial loading using the Euler-Bernoulli beam theory showed that 80.5% of the original force was transmitted through the tibia with an intact fibula, rising to 81.1% after a distal fibulectomy, and 100% with a proximal fibulectomy.ConclusionThis study describes a novel method of measuring axial tibial forces. We demonstrated that a fibular osteotomy increases axial tibial loading regardless of location, with the greatest increase after proximal fibular osteotomy. A contributing factor for this can be explained by a simple beam model. We therefore recommend a proximal fibular osteotomy when it is performed in the treatment of delayed and non-union of tibial midshaft fractures.