Magnetically driven antegrade intramedullary lengthening nails for tibial lengthening.

Aims: As an alternative to external fixators, intramedullary lengthening nails (ILNs) can be employed for distraction osteogenesis. While previous studies have demonstrated that typical complications of external devices, such as soft-tissue tethering, and pin site infection can be avoided with ILNs, there is a lack of studies that exclusively investigated tibial distraction osteogenesis with motorized ILNs inserted via an antegrade approach. Methods: A total of 58 patients (median age 17 years (interquartile range (IQR) 15 to 21)) treated by unilateral tibial distraction osteogenesis for a median leg length discrepancy of 41 mm (IQR 34 to 53), and nine patients with disproportionate short stature treated by bilateral simultaneous tibial distraction osteogenesis, with magnetically controlled motorized ILNs inserted via an antegrade approach, were retrospectively analyzed. The median follow-up was 37 months (IQR 30 to 51). Outcome measurements were accuracy, precision, reliability, bone healing, complications, and patient-reported outcome assessed by the Limb Deformity-Scoliosis Research Society Score (LD-SRS-30). Results: A median tibial distraction of 44 mm (IQR 31 to 49) was achieved with a mean distraction index of 0.5 mm/day (standard deviation 0.13) and median consolidation index of 41.2 days/cm (IQR 34 to 51). Accuracy, precision, and reliability were 91%, 92%, and 97%, respectively. New temporary range of motion limitations occurred in 51% of segments (34/67). Distraction-related equinus deformity treated by Achilles tendon lengthening was the most common major complication recorded in 16% of segments (11/67). In 95% of patients (55/58) the distraction goal was achieved with 42% unplanned additional interventions per segment (28/67). The median postoperative LD-SRS-30 score was 4.0 (IQR 3.6 to 4.3). Conclusion: Tibial distraction osteogenesis using motorized ILNs inserted via an antegrade approach appears to be a reliable and precise procedure. Temporary joint stiffness of the knee or ankle should be expected in up to every second patient. A high rate and wide range of complications of variable severity should be anticipated.

Evaluation of simultaneous bilateral femoral distraction osteogenesis with antegrade intramedullary lengthening nails in achondroplasia with rhizomelic short stature: a retrospective study of 15 patients with a minimum follow-up of 2 years.

BACKGROUND AND PURPOSE: Bilateral femoral distraction osteogenesis in patients with achondroplasia is insufficiently reported. We aimed to perform the first study that exclusively analyzed simultaneous bilateral femoral distraction osteogenesis with motorized intramedullary lengthening nails via an antegrade approach in patients with achondroplasia focused on reliability, accuracy, precision, and the evolving complications. PATIENTS AND METHODS: In this retrospective singlecenter study we analyzed patients with achondroplasia who underwent simultaneous bilateral femoral lengthening with antegrade intramedullary lengthening nails between October 2014 and April 2019. 15 patients (30 femoral segments) of median age 14 years (interquartile range [IQR] 12-15) were available for analysis. The median follow-up was 29 months (IQR 27-37) after nail implantation. RESULTS: The median distraction length per segment was 49 mm (IQR 47-51) with a median distraction index of 1.0 mm/day (IQR 0.9-1.0), and a median consolidation index of 20 days/cm (IQR 17-23). Reliability of the lengthening nails was 97% and their calculated accuracy and precision were 96% and 95%, respectively. The most common complication was temporary restriction of knee range of motion during distraction in 10 of 30 of the lengthened segments. 1 patient was treated with 2 unplanned additional surgeries due to premature consolidation. CONCLUSION: The method is reliable and accurate with few complications.

Radiographic reference values of the central knee anatomy in 8-16-year-old children.

BACKGROUND AND PURPOSE: For correction of leg-length discrepancy or angular deformity of the lower limb in skeletally immature patients temporary or permanent (hemi-)epiphysiodesis can be employed. These are reliable treatments with few complications. Recently, radiographic analysis of treatment-related alterations of the central knee anatomy gained interest among pediatric orthopedic surgeons. To date the comparison and adequate interpretation of potential changes of the central knee anatomy is limited due to the lack of defined standardized radiographic references. We aimed to establish new reference values of the central knee anatomy. PATIENTS AND METHODS: A retrospective analysis of calibrated longstanding anteroposterior radiographs of 254 skeletally immature patients with a chronological age ranging from 8 to 16 years was conducted. The following radiographic parameters were assessed: (1) femoral floor angle, (2) tibial roof angle, (3) width at femoral physis, and (4) femoral notch-intercondylar distance. RESULTS: All observed radiographic parameters were normally distributed with a mean age of 12.4 years (standard deviation [SD] 2, 95% confidence interval [CI] 12.2-12.6). Mean femoral floor angle was 142° (SD 6, CI 141.8-142.9), mean tibial roof angle was 144° (SD 5, CI 143.7-144.1), mean width at femoral physis was 73 mm (SD 6, CI 72.8-73.9), and mean femoral notch-intercondylar distance was 8 mm (SD 1, CI 7.5-7.7). The estimated intraclass correlation coefficient values were excellent for all measurements. CONCLUSION: This study provides new radiographic reference values of the central knee anatomy for children between 8 and 16 years and we suggest considering values within the range of 2 SD as the physiological range.

Antegrade Intramedullary Femoral Lengthening and Distal Temporary Hemiepiphysiodesis for Combined Correction of Leg Length Discrepancy and Coronal Angular Deformity in Skeletally Immature Patients.

Leg length discrepancies (LLD) are frequently associated with coronal malalignment. Temporary hemiepiphysiodesis (HED) is a well-established procedure for the correction of limb malalignment in skeletally immature patients. For treatment of LLD > 2 cm, lengthening with intramedullary devices gains increasing popularity. However, no studies have investigated the combined application of HED and intramedullary lengthening in skeletally immature patients. This retrospective single-center study evaluated the clinical and radiological outcomes of femoral lengthening with an antegrade intramedullary lengthening nail combined with temporary HED performed in 25 patients (14 females) between 2014 and 2019. Temporary HED through the implantation of flexible staples of the distal femur and/or proximal tibia was either performed prior (n = 11), simultaneously (n = 10) or subsequently (n = 4) to femoral lengthening. The mean follow-up period was 3.7 years (±1.4). The median initial LLD was 39.0 mm (35.0-45.0). Twenty-one patients (84%) presented valgus and four (16%) showed varus malalignment. Leg length equalization was achieved in 13 of the skeletally mature patients (62%). The median LLD of the eight patients with residual LLD > 10 mm at skeletal maturity was 15.5 mm (12.8-21.8). Limb realignment was observed in nine of seventeen skeletally mature patients (53%) in the valgus group, and in one of four patients (25%) in the varus group. Combining antegrade femoral lengthening and temporary HED is a viable option to correct LLD and coronal limb malalignment in skeletally immature patients; however, achieving limb length equalization and realignment may be difficult in cases of severe LLD and angular deformity, in particular.

Guided growth: angular deformity correction through temporary hemiepiphysiodesis with a novel flexible staple (FlexTack).

Temporary hemiepiphysiodesis (HED) is applied to children and adolescents to correct angular deformities (ADs) in long bones through guided growth. Traditional Blount staples or two-hole plates are mainly used for this indication. Despite precise surgical techniques and attentive postoperative follow-up, implant-associated complications are frequently described. To address these pitfalls, a flexible staple was developed to combine the advantages of the established implants. This study provides the first results of guided growth using the new implant and compares these with the established two-hole plates and Blount staples. Between January 2013 and December 2016, 138 patients (22 children, 116 adolescents) with genu valgum or genu varum were treated with 285 flexible staples. The minimum follow-up was 24 months. These results were compared with 98 patients treated with 205 two-hole plates and 92 patients treated with 535 Blount staples. In long-standing anteroposterior radiographs, mechanical axis deviations (MADs) were measured before and during treatment to analyze treatment efficiency. The evaluation of the new flexible staple was performed according to the idea, development, evaluation, assessment, long-term (IDEAL) study framework (Stage 2a). Overall, 79% (109/138) of patients treated with flexible staples achieved sufficient deformity correction. The median treatment duration was 16 months (interquartile range (IQR) 8 to 21). The flexible staples achieved a median MAD correction of 1.2 mm/month/HED site (IQR 0.6 to 2.0) in valgus deformities and 0.6 mm/month/HED site (IQR 0.2 to 1.5) in varus deformities. Wound infections occurred in 1%, haematomas and joint effusions in 4%, and implant-associated complications in 1% of patients treated with flexible staples. Valgus AD were corrected faster using flexible staples than two-hole plates and Blount staples. Furthermore, the median MAD after treatment was lower in varus and valgus AD, fewer implant-associated complications were detected, and reduced implantation times were recorded using flexible staples. The flexible staple seems to be a viable option for guided growth, showing comparable or possibly better results regarding correction speed and reducing implant-associated complications. Further comparative studies are required to substantiate these findings.

A clinical and radiological matched-pair analysis of patients treated with the PRECICE and STRYDE magnetically driven motorized intramedullary lengthening nails.

AIMS: Distraction osteogenesis with intramedullary lengthening devices has undergone rapid development in the past decade with implant enhancement. In this first single-centre matched-pair analysis we focus on the comparison of treatment with the PRECICE and STRYDE intramedullary lengthening devices and aim to clarify any clinical and radiological differences. METHODS: A single-centre 2:1 matched-pair retrospective analysis of 42 patients treated with the STRYDE and 82 patients treated with the PRECICE nail between May 2013 and November 2020 was conducted. Clinical and lengthening parameters were compared while focusing radiological assessment on osseous alterations related to the nail's telescopic junction and locking bolts at four different stages. RESULTS: Osteolysis next to the telescopic junction was observed in 31/48 segments (65%) lengthened with the STRYDE nail before implant removal compared to 1/91 segment (1%) in the PRECICE cohort. In the STRYDE cohort, osteolysis initially increased, but decreased or resolved in almost all lengthened segments (86%) after implant removal. Implant failure was observed in 9/48 STRYDE (19%) and in 8/92 PRECICE nails (9%). Breakage of the distal locking bolts was found in 5/48 STRYDE nails (10%) compared to none in the PRECICE cohort. Treatment-associated pain was generally recorded as mild and found in 30/48 patients (63%) and 39/92 (42%) in the STRYDE and PRECICE cohorts, respectively. Temporary range of motion (ROM) limitations under distraction were registered in 17/48 (35%) segments treated with the STRYDE and 35/92 segments (38%) treated with the PRECICE nail. CONCLUSION: Osteolysis and periosteal reaction, implant breakage, and pain during lengthening and consolidation is more likely in patients treated with the STRYDE nail compared to the PRECICE nail. Temporary ROM limitations during lengthening occurred independent of the applied device. Implant-related osseous alterations seem to remodel after implant removal.Cite this article: Bone Joint J 2023;105-B(1):88-96.

LIMB-Q Kids-German Translation and Cultural Adaptation.

(1) Purpose: Lower limb deformities can have a severe impact on health-related quality of life (HRQL). LIMB-Q Kids is a new patient-reported outcome measure (PROM) aiming to elucidate the experience of 8-18-year-old patients before, during and after treatment, and to measure the different aspects of HRQL. The aim of this study was to translate and culturally adapt LIMB-Q Kids to German. (2) Methods: The International Society for Pharmacoeconomics and Outcomes Research (ISPOR) guidelines were followed. Three forward translations, a backward translation, an expert panel meeting with eight participants, and twenty cognitive debriefing interviews led to the final German version of LIMB-Q Kids. (3) Results: In the forward translations, 4/159 items were difficult to translate, and 2/159 items in the backward translation differed from the original English version. Cognitive debriefing interviews with 20 patients identified 7/159 items that were difficult to comprehend/answer, and 2 of these items were changed. (4) Conclusions: Lower limb deformities can have a great impact on children, and it is important to measure and consider the impact on HRQL. In order to be able to use PROMs in different countries, conceptually equivalent translations and cultural adaptations should be performed in order to ensure comprehensibility. The final German version of LIMB-Q Kids is ready for use in an international field test.

Preliminary results of two novel devices for epiphysiodesis in the reduction of excessive predicted final height in tall stature.

BACKGROUND: In the treatment of tall stature, the reduction of excessive predicted final height can either be achieved by hormonal treatment or surgically by temporary (tED) or permanent (pED) epiphysiodesis. The present study evaluates the preliminary results of two novel devices for tED and pED around the knee to reduce the predicted final height. MATERIALS AND METHODS: A retrospective analysis was performed to evaluate the clinical and radiographic outcome after bilateral epiphysiodesis for the treatment of tall stature. A cohort of 34 patients (16 girls, 18 boys) who underwent either tED or pED between 2015 and 2020 were eligible for analysis based on the electronic patient records and picture archiving and communication system of our orthopaedic teaching hospital. tED was conducted in 11 patients (32%) through bilateral implantation of four RigidTacks™ (Merete, Berlin, Germany) around the knee. Twenty-three patients (68%) received pED, performed with an EpiStop™ trephine (Eberle, Wurmberg, Germany). The mean overall follow-up time was 2.9 years. RESULTS: The mean age at surgery was 12.3 years in girls and 13.2 years in boys. Patients had a mean body height of 175.2 cm in girls and 184.7 cm in boys at surgery. The mean predicted final height was 191.4 cm in girls and 210.4 cm in boys. At the last follow-up, 26 patients (76.5%) had achieved skeletal maturity. The mean height of skeletally mature patients was 187.2 cm in girls and 198.5 cm in boys. A mean reduction of the predicted final height of 5.9 cm in girls and 8.7 cm in boys was achieved, corresponding to a reduction in remaining growth of 46% in girls and 38% in boys. Secondary frontal plane deformities of the knee were detected in 5/11 patients (45.5%) in the tED group and 1/23 treatments (4.3%) in the pED group. CONCLUSIONS: tED and pED have both proven to be efficient at achieving growth inhibition to reduce excessive predicted height. However, tED has been associated with an increased risk of secondary angular deformities of the knee. Furthermore, the risk of implant-related complications and the necessity of a subsequent surgical intervention for implant removal have led our study group to abandon tED when treating tall stature. Long-term results of both procedures are pending.

German Translation and Cross-Cultural Adaptation of the Limb Deformity-Scoliosis Research Society (LD-SRS) Questionnaire.

BACKGROUND: Patient-reported outcome measures are gaining increasing importance in clinical research and quality control. Clinical impairment through limb deformities can appear in various forms. This study aimed at translating and culturally adaptating the Limb Deformity-Scoliosis Research Society (LD-SRS) patient-reported outcome measure (PROM) into German by following the scientific rigor of the cross-cultural adaptation process as well as ensuring the reliability of the translated version. The LD-SRS is applicable in children and adults. METHODS: The translation was performed in accordance with the creators of the LD-SRS following the Professional Society for Health Economics and Outcomes Research (ISPOR) guidelines for translation and cultural adaptation. Two forward translations were performed, and after a consensus meeting, a professional translator translated the PROM back to English. The creators reviewed the back translation of the preliminary German version. Thirty patients with upper and lower limb deformities participated in cognitive debriefing interviews. The version was proofread and, finally, the test-retest reliability was estimated. RESULTS: The mean age was 19 years (range 6-61). Twenty-six patients (87%) completed the retest after 6 days (range 3-26). The internal consistency was estimated with a Cronbach's alpha of 0.96 (range 0.94-0.97), and the intraclass correlation was 0.92 (range 0.89-0.94), indicating an excellent reliability. The scores were normally distributed. Thereafter, the German version was proofread and finalized. CONCLUSIONS: The German translation and cross-cultural adaptation of the LD-SRS score resulted in a high reliability and internal consistency. The German LD-SRS score is readily usable and may be applied in future studies of German-speaking limb deformity patients.

MUTARS® Humero pro Femur replacement: A novel reconstructive procedure after malignant bone tumor resection of the femur in young children.

Limb-preserving surgery in young children suffering malignant bone tumor of the femur is challenging due to the specific anatomical conditions. Extendable tumor endoprostheses are often oversized, while custom-made endoprostheses do not provide the intraoperatively required variability regarding reconstruction length. Allo- and autograft replacements, on the other hand, show high complication and revision rates. We report a novel reconstructive procedure after resection of malignant bone tumors of the femur in young children, and present our preliminary results of this technique.

Callus distraction for brachymetatarsia - A comparison between an internal device and the external fixator.

BACKGROUND: Symptomatic patients with severe brachymetatarsia are commonly treated with callus distraction using external mini-fixator (EF) or internal device (ID). This study points out advantages and limitations of both methods comparing clinical and radiographical parameters. METHODS: Retrospective analysis of 21 metatarsal bones in twelve patients. Twelve metatarsals were treated with ID (Genos Mini), nine with EF (MiniRail). RESULTS: Mean lengthening distance was 17.3 mm using EF and 11.7 mm using ID (p = 0.016). Adverse results were observed in 89% of metatarsals treated with EF and in 33% treated with ID (p = 0.011). Postoperative surgical intervention was required in 33% using EF compared to 0% using ID (p = 0.031). Mean total German Foot Function Index (FFI-T) improved from 49 to 33 using EF and from 47 to 22 using ID (p < 0.001). CONCLUSION: CD is a reliable surgical treatment for BMT. Surgeons should be aware of implant-related advantages and complications when counseling patients about treatment options.

What Are the Risks and Functional Outcomes Associated With Bilateral Humeral Lengthening Using a Monolateral External Fixator in Patients With Achondroplasia?

BACKGROUND: Many patients with achondroplasia experience functional impairments because of rhizomelic upper extremities (proximal limb shortening). Bilateral humeral lengthening may overcome these functional limitations, but it is associated with several risks, such as radial nerve palsy and insufficient bone regeneration. Only a few studies have reported on patient satisfaction and functional outcome after humeral lengthening in patients with achondroplasia. Furthermore, the reported numbers of adverse events associated with lengthening procedures using external fixators vary widely. QUESTIONS/PURPOSES: (1) Does bilateral humeral lengthening with a monolateral external fixator in patients with achondroplasia reliably improve patient function and autonomy, and what proportion of patients achieved at least 8 cm of humeral lengthening? (2) What adverse events occur after bilateral humeral lengthening with monolateral external fixators? METHODS: Between 2011 and 2019, 44 patients underwent humeral lengthening at our institution. Humeral lengthening was performed in patients with severe shortening of the upper extremities and functional impairments. In humeri in which intramedullary devices were not applicable, lengthening was performed with monolateral external fixators in 40 patients. Eight patients were excluded because they underwent unilateral lengthening for etiologies other than achondroplasia, and another four patients did not fulfill the minimum study follow-up period of 2 years, leaving 28 patients with bilateral humeral lengthening to treat achondroplasia available for analysis in this retrospective study. The patients had a median (interquartile range) age of 8 years (8 to 10), and 50% (14 of 28) were girls. The median follow-up time was 6 years (4 to 8). The median humeral lengthening was 9 cm (9 to 10) with a median elongation of 73% (67% to 78%) from an initial median length of 12 cm (11 to 13). To determine whether this treatment reliably improved patient function and autonomy, surgeons retrospectively evaluated patient charts. An unvalidated retrospective patient-reported outcome measure questionnaire consisting of nine items (with answers of "yes" or "no" or a 5-point Likert scale) was administered to assess the patient's functional improvement in activities of daily living, physical appearance, and overall satisfaction, such that 45 points was the highest possible score. The radiographic outcome was assessed on calibrated radiographs of the humerus. To ascertain the proportion of adverse events, study surgeons performed a chart review and telephone interviews. Major complications were defined as events that resulted in unplanned revision surgery, nerve injury (either temporary or permanent), refracture of the bone regenerate, or permanent functional sequelae. Minor complications were characterized as events that resolved without further surgical interventions. RESULTS: On our unvalidated assessment of patient function and independence, all patients reported improvement at their most recent follow-up compared with scores obtained before treatment (median [IQR] 24 [16 to 28] before surgery versus 44 [42 to 45] at latest follow-up, difference of medians 20 points, p < 0.001). A total of 89% (25 of 28) of patients achieved the desired 8 cm of lengthening in both arms. A total of 50% (14 of 28) of our patients experienced a major complication. Specifically, 39% (11 of 28) had an unplanned reoperation, 39% (11 of 28) had a radial nerve palsy, 18% (5 of 28) had a refracture of the regenerate, and 4% (1 of 28) concluded treatment with a severe limb length discrepancy. In addition, 82% (23 of 28) of our patients experienced minor complications that resolved without further surgery and did not involve radial nerve symptoms. Radial nerve palsy was observed immediately postoperatively in eight of 13 segments, and 1 to 7 days postoperatively in five of 13 segments. The treatment goal was not achieved because of radial nerve palsy in 5% (3 of 56) of lengthened segments, which occurred in 7% (2 of 28) of patients. Full functional recovery of the radial nerve was observed in all patients after a median (IQR) of 3 months (2 to 5). Refractures of bone regenerates were observed in 11% (6 of 56) of humeri in 18% (5 of 28) of patients. Of those refractures, 1 of 6 patients was treated nonsurgically with a hanging cast, while 5 of 6 patients underwent revision surgery with intramedullary rodding. CONCLUSION: Most patients with achondroplasia who underwent humeral lengthening achieved the treatment goal without permanent sequelae; nonetheless, complications of treatment were common, and the road to recovery was long and often complicated, with many patients experiencing problems that were either painful (such as refracture) or bothersome (such as temporary radial nerve palsy). However, using a subjective scale, patients seemed improved after treatment; nevertheless, robust outcomes tools are not available for this condition, and so we must interpret that finding with caution. Considering our discoveries, bilateral humeral lengthening with a monolateral external fixator should only be considered in patients with severe functional impairments because of rhizomelic shortening of the upper extremities. If feasible, internal lengthening devices might be preferable, as these are generally associated with higher patient comfort and decreased complication rates compared with external fixators. LEVEL OF EVIDENCE: Level IV, therapeutic study.

What Are the Potential Benefits and Risks of Using Magnetically Driven Antegrade Intramedullary Lengthening Nails for Femoral Lengthening to Treat Leg Length Discrepancy?

BACKGROUND: Limb lengthening with magnetically driven intramedullary lengthening nails is a fast-developing field and represents an alternative to external fixators. Although previous studies have assessed the application of magnetically driven intramedullary lengthening nails, these studies have been heterogenous regarding the nailing approach, the bone treated, and the implant type; they also have analyzed relatively small patient groups at short follow-up durations. QUESTIONS/PURPOSES: (1) Is femoral lengthening with magnetically driven antegrade intramedullary lengthening nails accurate and precise? (2) What are the most common complications of treatment? (3) What factors are associated with unplanned additional surgery? METHODS: We retrospectively analyzed the longitudinally maintained database of our orthopaedic teaching hospital to identify all patients who underwent surgery for leg length discrepancy (LLD) between October 2014 and April 2019. In total, we surgically treated 323 patients for LLD of 2 cm or more. Of those 55% (177 of 323) were treated with distraction osteogenesis with magnetically driven intramedullary lengthening nails, 18% (59 of 323) with external fixation, and 27% (87 of 323) with epiphysiodesis around the knee. Based on that, 29% (93 of 323) of patients underwent unilateral femoral distraction osteogenesis with magnetically driven antegrade femoral lengthening nails and were eligible for analysis. No patient was excluded, and 3% (3 of 93) were lost before the minimum study follow-up of 2 years, leaving 97% (90 of 93) for analysis. Patients with a distal femoral deformity were treated via a retrograde femoral approach (10% [33 of 323]) or with external fixators (3% [10 of 323]) and were not included in this study. Distraction osteogenesis with magnetically driven intramedullary lengthening nails was not considered for patients with deep tissue infection, those with bone dimensions considered to be too small in relation to the available implants, and for patients younger than 8 years. This study included 90 patients (44 females, 43 left femora) treated for a median (interquartile range) preoperative LLD of 39 mm (32 to 52) at a median age of 15 years (14 to 17). The same limb lengthening system was applied in all patients. The median (IQR) follow-up was 35 months (24 to 78). Data were acquired through a chart review performed by someone not involved in the surgical care of the included patients. Data acquisition was supervised and curated by two of the involved surgeons. Accuracy was calculated as 100 - [(achieved distraction in mm - planned distraction in mm) / (planned distraction in mm) x 100] and precision as 100 - (relative standard deviation of accuracy). Treatment-associated complications were summarized descriptively and characterized as complications resulting in unplanned additional surgery or those not resulting in unplanned surgery. To analyze the risk of unplanned additional surgery by entity, we calculated odds ratios (ORs) comparing the incidence of unplanned additional surgery in the different entity cohorts with the idiopathic LLD cohort as a reference. By calculating ORs, we analyzed the risk for unplanned additional surgery depending on sex, age, surgery time, and previous lengthening. Due to the lack of long-term evidence about motorized lengthening nails remaining in situ and concerns about potential implant-related adverse effects, removal was routinely scheduled 1 year after consolidation. For implant removal, 92% (83 of 90) of patients underwent planned additional surgery, which was not recorded as an adverse event of the treatment. Ninety-seven percent (87 of 90) of patients completed lengthening with the implant remaining in situ until the end of distraction. The median (IQR) distraction length was 37 mm (30 to 45) with a median distraction index of 0.9 mm/day (0.7 to 1.0) and median consolidation index of 31 days/cm (25 to 42). RESULTS: The calculated accuracy and precision were 94% and 90%, respectively. In total, 76% (68 of 90) of our patients experienced complications, which resulted in 20% (18 of 90) of patients undergoing unplanned additional surgery. The most common complication overall was adjustment of the distraction rate in 27% (24 of 90) of patients (faster: 16% [14 of 90]; slower: 11% [10 of 90]) and temporary restriction of knee motion, which occurred in 20% (18 of 90) of our patients and resolved in all patients who experienced it. The most serious complications were bacterial osteomyelitis and knee subluxation, which occurred in 3% (3 of 90) and 1% (1 of 90) of our patients, respectively. With the numbers available, we found only one factor associated with an increased likelihood of unplanned additional surgery: Patients with postinfectious LLD had higher odds of unplanned additional surgery than patients with idiopathic LLD (7% [1 of 15] versus 50% [3 of 6], OR 14.0 [95% CI 1.06 to 185.49]; p = 0.02). However, we caution readers this finding is fragile, and the confidence interval suggests that the effect size estimate is likely to be imprecise. CONCLUSION: Femoral distraction osteogenesis with magnetically driven antegrade intramedullary lengthening nails appears to be an accurate and reliable treatment for femoral lengthening. However, depending on the etiology, a high risk of unplanned additional surgery should be anticipated, and a high proportion of patients will experience temporary joint stiffness. We recommend close orthopaedic follow-up and physiotherapy during treatment. This treatment of LLD can be considered alongside other nails, external fixators, and epiphysiodesis. Multicenter studies comparing this with other approaches are needed. LEVEL OF EVIDENCE: Level IV, therapeutic study.

Growth arrest: leg length correction through temporary epiphysiodesis with a novel rigid staple (RigidTack).

AIMS: Temporary epiphysiodesis (ED) is commonly applied in children and adolescents to treat leg length discrepancies (LLDs) and tall stature. Traditional Blount staples or modern two-hole plates are used in clinical practice. However, they require accurate planning, precise surgical techniques, and attentive follow-up to achieve the desired outcome without complications. This study reports the results of ED using a novel rigid staple (RigidTack) incorporating safety, as well as technical and procedural success according to the idea, development, evaluation, assessment, long-term (IDEAL) study framework. METHODS: A cohort of 56 patients, including 45 unilateral EDs for LLD and 11 bilateral EDs for tall stature, were prospectively analyzed. ED was performed with 222 rigid staples with a mean follow-up of 24.4 months (8 to 49). Patients with a predicted LLD of ≥ 2 cm at skeletal maturity were included. Mean age at surgery was 12.1 years (8 to 14). Correction and complication rates including implant-associated problems, and secondary deformities as well as perioperative parameters, were recorded (IDEAL stage 2a). These results were compared to historical cohorts treated for correction of LLD with two-hole plates or Blount staples. RESULTS: The mean LLD was reduced from 25.2 mm (15 to 45) before surgery to 9.3 mm (6 to 25) at skeletal maturity. Implant-associated complications occurred in 4/56 treatments (7%), and secondary frontal plane deformities were detected in 5/45 legs (11%) of the LLD cohort. Including tall stature patients, the rate increased to 12/67 legs (18%). Sagittal plane deformities were observed during 1/45 LLD treatments (2%). Compared to two-hole plates and Blount staples, similar correction rates were observed in all devices. Lower rates of frontal and sagittal plane deformities were observed using rigid staples. CONCLUSION: Treatment of LLD using novel rigid staples appears a feasible and promising strategy. Secondary frontal and sagittal plane deformities remain a potential complication, although the rate seems to be lower in patients treated with rigid staples. Further comparative studies are needed to investigate this issue. Cite this article: Bone Joint J 2021;103-B(8):1428-1437.

Focal osteolysis and corrosion at the junction of Precice Stryde intramedullary lengthening device : preliminary clinical, radiological, and metallurgic analysis of 57 lengthened segments.

AIMS: This study aims to enhance understanding of clinical and radiological consequences and involved mechanisms that led to corrosion of the Precice Stryde (Stryde) intramedullary lengthening nail in the post market surveillance era of the device. Between 2018 and 2021 more than 2,000 Stryde nails have been implanted worldwide. However, the outcome of treatment with the Stryde system is insufficiently reported. METHODS: This is a retrospective single-centre study analyzing outcome of 57 consecutive lengthening procedures performed with the Stryde nail at the authors' institution from February 2019 until November 2020. Macro- and microscopic metallographic analysis of four retrieved nails was conducted. To investigate observed corrosion at telescoping junction, scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDX) were performed. RESULTS: Adjacent to the nail's telescoping junction, osteolytic changes were observed in bi-planar radiographs of 20/57 segments (35%) after a mean of 9.5 months (95% confidence interval 7.2 to 11.9) after surgery. A total of 8/20 patients with osseous alterations (40%) reported rest and ambulation pain of the lengthened segment during consolidation. So far, 24 Stryde nails were retrieved and in 20 (83%) macroscopic corrosion was observed at the nail's telescoping junction. Before implant removal 11/20 radiographs (55%) of lengthened segments with these 20 nails revealed osteolysis. Implant retrieval analysis by means of SEM showed pitting and crevice corrosion. EDX detected chromium as the main metallic element of corrosion. CONCLUSION: Patients are exposed to the risk of implant-related osteolysis of unclear short- and long-term clinical consequences. The authors advocate in favour of an early implant removal after osseous consolidation. Cite this article: Bone Joint Res 2021;10(7):425-436.

Staged reconstruction of unilateral neglected hip dislocation through total hip arthroplasty and subsequent intramedullary femoral lengthening.

BACKGROUND AND PURPOSE: Total hip arthroplasty (THA) is a successful approach to treat unilateral symptomatic neglected hip dislocation (NHD). However, the extensive leg length discrepancy (LLD) can hereby only be partially corrected. In case of residual LLD of more than 2 cm, subsequent femoral lengthening can be considered. PATIENTS/MATERIAL/METHODS: Retrospective analysis of clinical data and radiographs of five patients (age 38.1 (28-51) years) with unilateral NHD who underwent THA with (n = 3) or without (n = 2) subtrochanteric shortening osteotomy (SSO) and secondary intramedullary femoral lengthening through a retrograde magnetically-driven lengthening nail (follow-up 18.4 (15-27) months). RESULTS: LLD was 51.0 (45-60) mm before and 37.0 (30-45) mm after THA. Delayed bone union at one SSO site healed after revision with autologous bone grafting and plate fixation. Subsequent lengthening led to leg length equalisation in all patients. Complete consolidation was documented in all lengthened segments. CONCLUSION: Staged reconstruction via THA and secondary femoral lengthening can successfully be used to reconstruct the hip joint and equalise LLD. The specific anatomical conditions have to be taken into consideration when planning treatment, and patients ought to be closely monitored.

Subtalar Arthroereisis for Flexible Flatfoot in Children-Clinical, Radiographic and Pedobarographic Outcome Comparing Three Different Methods.

Subtalar arthroereises (STA) is a minimally invasive and reversible surgery to correct symptomatic flexible flatfoot (FFF) in children. Various techniques were described either applying expandable sinus tarsi implants or lateral calcaneus stop screws. Studies comparing the outcome of STA with different devices are rare. This retrospective single-center cohort study analyzes the results of STA using three different implants. 113 STA were performed in 73 consecutive patients (28 females). Mean age at surgery was 10.8 years (range 5-16). Mean follow-up was 29.0 months (range 1-111). In 21 feet the non-absorbable Kalix® endorthesis and in 56 feet the absorbable Giannini endorthesis were applied. Subtalar extraarticular screw arthroereises (SESA) was conducted in 36 feet. Clinical, radiographic and pedobarographic parameters were analyzed. No intraoperative complications were observed. All three procedures achieved comparable improvements of the clinical, radiographic and pedobarographic parameters. The mean foot function index (FFI) improved from 36.4 (range 12-63) to 22.8 (range 2-55). The mean preoperative calcaneal inclination angle and the lateral talocalcaneal angle improved from 9.5° (range 0-22) and 42.3° (range 21-62) to 12.8° (range 0-26) and 37.6° (range 15-56), respectively. Pedobarographically determined values of the arch index, the medial midfoot contact area and the medial forefoot peak pressure decreased. In contrast to SESA (1/36, 3%), a higher incidence of implant-related complications was observed using Kalix® (6/21, 29%) and Giannini (10/56, 8%) sinus tarsi implants. Peroneal muscle contractures only occurred in the SESA group (4/36, 11%). Premature removal due to treatment-related complications was necessary in 6/21 Kalix® implants (29%), 4/56 Giannini implants (7%) and 4/36 SESA implants (11%). Implant choice for treatment of painful FFF in children with STA seems to play a subordinate role. Clinical, radiographic and pedobarographic outcomes are comparable between the applied implants. Surgeons and patients should be aware of the different spectrum of implant-related complications. Treatment can be reliably monitored by radiation-free pedobarography providing dynamic information about the deformity.

Temporary Proximal Tibial Epiphysiodesis for Correction of Leg Length Discrepancy in Children-Should Proximal Fibular Epiphysiodesis Be Performed Concomitantly?

The need for concomitant proximal fibular epiphysiodesis (PFE) when correcting leg length discrepancy (LLD) with temporary proximal tibial epiphysiodesis (PTE) in children is controversially discussed. This single center, retrospective cohort study analyzes proximal fibular growth in patients treated by PTE with and without concomitant PFE. Radiographic measurements were conducted before implantation and at implant removal. The position of the fibular head in relation to the tibia was assessed with recently established radiographic reference values. All patients (n = 58, 19 females) received PTE to treat LLD at a mean age of 12.2 years (range 7 to 15). In 27/58 (47%) concomitant PFE was performed. Mean follow-up was 36.2 months (range 14.2 to 78.0). The position of the proximal fibula at implant removal was within physiological range in 21/26 patients (81%) with PFE and in 21/30 patients (70%) without PFE. Proximal fibular overgrowth newly developed in 2/26 patients (8%) treated with PFE and in 5/30 patients (17%) treated without PFE (p = 0.431). Peroneal nerve injury or discomfort due to proximal fibular overlength was not reported. The position of the proximal fibula should be critically assessed preoperatively under consideration of reference values before PTE. In consequence of this study, the authors do not routinely perform PFE concomitantly with PTE for correction of moderate LLD in children if the proximal fibula is localized within physiological radiographic margins determined by the established reference values.

Comparison of histomorphometric and radiographic effects of growth guidance with tension-band devices (eight-Plate and FlexTack) in a pig model.

Background and purpose - Temporary hemiepiphysiodesis for growth modulation in skeletally immature patients is a long-known technique. Recently the use of tension-band devices has become popular. This study compares 2 tension-band implants (eight-Plate and FlexTack) regarding their effects on the growth plate.Animals and methods - 12 pigs in 2 equally sized groups (A and B) were investigated. The right proximal medial tibia was treated with either eight-Plate or FlexTack. The left tibia of the same pig was treated with the opposite implant. After 9 weeks all implants were removed. Animals in group B were then hosted for another 5 weeks. Histomorphometric analysis of the growth plate was carried out after 9 and 14 weeks, respectively. Radiographs were taken at implantation, removal, and after 14 weeks.Results - Both tension-band devices achieved a statistically significant and clinically relevant growth inhibition, whereas the effect appeared to be more distinct after the use of FlexTack. Implant-related complications or physeal damage was not observed. After implant removal, rebound phenomenon was radiologically observed in all cases. The growth plates treated with eight-Plate showed a paradox reversal of the zonal distributions, with an increase of the proliferative zones at the previously arrested medial aspect of the physis and a decrease laterally.Interpretation - Both eight-Plate and FlexTack proved to be appropriate devices for growth-guiding treatment. The radiographic evaluation showed a change in angular axes after treatment with each implant, while the correction appeared to be faster with FlexTack. The paradox cartilaginous reaction observed after removal of the eight-Plate might be a histopathological correlate for rebound phenomenon.

Chondroblastoma: Is intralesional curettage with the use of adjuvants a sufficient way of therapy?

BACKGROUND: Chondroblastoma is a rare benign cartilaginous bone tumor that represents 1-2% of all primary bone tumors. It is characterized by aggressive growth, possible recurrence after surgical treatment and, in rare cases, metastasis. Surgical management is the primary treatment and includes intralesional curettage with or without adjuvants. Local recurrence rates vary between less than 10% up to more than 30%. METHODS: In this retrospective study between 2009 and 2020 we analysed 38 cases of chondroblastoma with a mean follow-up of 27.9 months who underwent a surgical treatment in our institution. Epidemiological data, radiographic and histological examinations, different surgical techniques, complications and local recurrence were evaluated to comment on the question if curettage with or without adjuvants is a sufficient way of therapy. RESULTS: The study includes 25 male (65.8%) and 13 female (34.2%) patients with a mean age of 17.2 (11-51) years. The most common location of manifestation was the proximal epiphyseal humerus (34.2%), followed by the proximal tibia (26.3%) and the distal femur (15.8%). Joint involvement occurred in 28 patients (73.7%). In all cases intralesional curettage was performed; in 25 cases (65.8%) the resulting cavity was filled with bone substitute, in 7.9% (3 cases) with bone cement and in 10.5% (4 cases) with autogenous bone graft. Adjuvant hydrogen peroxide was used in 64.9% of the cases. The overall recurrence rate was 39.5% (15 cases). The following subgroup analysis showed a recurrence rate of 100% (4/4 cases) after curettage and defect reconstruction with autogenous bone. In the case of intralesional curettage and filling of the cavity with bone substitute but without use of adjuvant the recurrence rate was 50% (4/8 cases). A low recurrence rate of 11.8% (2 cases) was observed in the case of intralesional curettage, using hydrogen peroxide as adjuvant (17 cases) and bone substitute for defect reconstruction. CONCLUSIONS: Chondroblastoma represents a rare pathology. Therapeutically an aggressive intralesional curettage with use of hydrogen peroxide as adjuvant and filling up the defect with bone substitute leads to low recurrence rates.