The treatment of leg length discrepancies, bone defects and deformities is highly complex. Distraction osteogenesis (callus distraction) is often used for this purpose. Nowadays, the previously used external fixators have increasingly been replaced by intramedullary, fully implantable motorized systems. These are used in combination with innovative planning methods and minimally invasive surgical techniques. This enables reliable and safe treatment with improved patient comfort. In contrast to external fixation, particularly modern external hexapod systems, intramedullary devices once implanted fix the bone fragments in both axial alignment and rotation. Thus, meticulous analysis and planning as well as exact intraoperative execution, are essential for successful treatment outcomes. This article summarizes the relevant intramedullary techniques and indications as well as the practical implementation, taking the current published evidence into account.

Die Behandlung von Beinlängendifferenzen, Knochendefekten und Deformitäten ist hochkomplex. Oft kommt die Distraktionsosteogenese (Kallusdistraktion) zur Anwendung. Inzwischen sind die vormals zur Kallusdistraktion eingesetzten externen Fixateure zunehmend abgelöst durch intramedulläre, vollimplantierbare, motorisierte Systeme, die mit innovativen Planungs- und schonenden chirurgischen Verfahren kombiniert werden. Dies ermöglicht die zuverlässige und sichere Durchführung der Behandlung mit höherem PatientInnenkomfort. Im Gegensatz zur externen Fixation, im Besonderen zu modernen externen Hexapoden-Systemen, sind die Fragmente nach Einbringung der intramedullären Systeme in Achse und Rotation fixiert. Für den Behandlungserfolg sind daher die sorgfältige Analyse und Planung sowie eine akribische intraoperative Umsetzung unabdinglich. Der Beitrag fasst entsprechende intramedulläre Verfahren und Indikationen sowie die praktische Umsetzung unter Berücksichtigung der aktuellen Datenlage zusammen.

Background: Partial or total avoidance of weight-bearing by a lower limb is regularly needed after trauma and surgery. There are approximately 200 such cases per 100 000 persons per year. Forearm crutches have mainly been used in Germany until now to keep these patients mobile. For those who lack the strength or co- ordination needed to use crutches, a wheelchair may become necessary, or they might find themselves forced to continue weight- bearing on the affected limb, with possible impending adverse consequences and complications. Methods: The supplementary use of a new type of orthopedic scooter by patients who must avoid weight-bearing by a lower limb, wholly or in part, was studied in a multicenter randomized controlled trial involving 88 subjects. The endpoints were improvement in quality of life (EQ5D, SF36) and improved abilities in everyday life (retrospective registration: DRKS00032980). Results: Patients who used orthopedic knee scooters (KS) reported a better overall state of health more frequently than those who used forearm crutches (UC) (SF-36 score: 67 [KS group], 95% CI [61; 73]; 59 [UC group], [53; 64]). They also reported less anxiety and depressed mood, greater mobility, and more independence than the patients who used crutches. In addition, they more frequently reported being able to transport themselves 4 x 500 meters in less than 20 minutes (n = 30 [KS], 63.8% [48.5; 77.3]; n = 6 [UC], 14.6% [5.6, 29.2]). Conclusion: The supplementary use of an orthopedic knee scooter can improve these patients' mobility and independence and prolong the distance over which they can transport themselves. For many patients, this form of treatment may well shorten the time of their total or partial inability to work and thus lower the socioeconomic costs of lower limb injuries and surgery.

Background: The gold standard for evaluating leg alignment is a long leg standing radio-graph (LSR). The research states that a correct LSR should have a patella that is centered and facing forward as well as a fibula head superimposition (FHS) with a tibia that is 1/3 larger than the fibula. The purpose of this study was to determine levels of quality for LSR by quantifying and correlating the patella position and fibular head superimposition. Method: 741 lower limbs were included using two distinct measurement techniques, we calculated the patella position's (PD) departure from the center of the knee joint (M1 and M2). To measure the inter-rater dependability in assessing PD and FHS, intraclass cor-relation coefficients were determined. The Bland-Altman approach was used to compare M1 with M2's performance. We created three quality groups based on the average quantity of PD. Results: The mean PD was 3.5 mm for M1 and 4.1 mm for M2, respectively. Three quality categories were created: group A for PD <= 5 mm, group B for PD 5-10 mm, and group C for PD of >= 10 mm. Group A takes up 70.9% of the LSR. Interestingly, group A's FHS was 21.3% than the typical value of 1/3. Conclusions: The patella's center should be centered within a 5 mm range and the fibular head should be 1/5 covered from the tibia. This study is the first to define quantitative met-rics based on LSR analysis. Level of Evidence: Level IV (diagnostic retrospective case series).(c) 2023 Published by Elsevier B.V.

Bei komplexen Deformitäten ist eine genaue präoperative Planung in allen Ebenen wesentliche Voraussetzung vor der eigentlichen Operation und kann Komplikationen und Folgeeingriffe verhindern. Wie auch die Operationstechniken selbst, verändern sich die Planungsmethoden weiter, sodass mittlerweile neben der 2‑D-Darstellung die 3‑D-Planung immer mehr in den Fokus rückt. Diese baut auf den Prinzipien der 2‑D-Planung auf, liefert aber wesentlich mehr Informationen z. B. auch für die patellofemorale Anatomie. Die Produktion patientenspezifischer Instrumente (PSI) oder die Anwendung der Robotik ähnlich wie in der Knieprothetik sind neue Möglichkeiten, die sich aus der 3‑D-Planung ergeben.

Die Kallusdistraktion (KD) ist eine Technik, die erfolgreich zur Behandlung von Beinlängendifferenzen und zur Rekonstruktion langstreckiger Knochendefekte angewandt werden kann. Im Zuge einer graduellen Distraktion der Knochenfragmente um ca. 1 mm/Tag kommt es zur Hypervaskularisierung und zum verstärkten Knochenheilungspotenzial (Wachstumsstimulus). Bisher kommt die KD fast ausschließlich longitudinal zur Anwendung, um neues, biologisch aktives Knochengewebe zu generieren. Chronische Wunden, Ulzera und Osteitiden gerade im Fußbereich stellen für den behandelnden Chirurgen immer wieder eine Herausforderung dar, da die Therapieformen langwierig, unsicher im Ausgang und mit möglichem Verlust der Extremität vergesellschaftet sind. Die transverse Kallusdistraktion (tKD) nutzt translational den Wachstumsstimulus der KD zur Behandlung von distal gelegenen, chronischen Wunden und führt dadurch zu einer Beschleunigung der Wundheilung. Am Ende der 5‑wöchigen Behandlung findet sich das weit proximal der chronischen Wunde gelegene, transvers distrahierte, Fragment wieder an seinem ursprünglichen Ort. Der biologische Stimulus wirkt lange nach – länger als die tKD selbst. Weitere Untersuchungen zu den Wirkmechanismen und Behandlungsergebnissen der tKD sind erforderlich. Sollten sich die bisherigen Ergebnisse bestätigen, kann die tKD zum „game changer“ werden und den Extremitätenerhalt bei einem großen Anteil bisher amputationswürdiger Befunde ermöglichen.

To firstly examine the pain levels during distraction osteogenesis (DO) with lengthening nails (LN) in a large sample. A total of 168 cases underwent DO of the tibia or femur with five different models of LN. Under a standardized medical regime, daily pain levels were noted as nominal rating scale (NRS) score (0–10) during the distraction phase. NRS scores and several potential influence factors (LN model, bone, approach, side, age, gender) were evaluated. The mean distraction length was 39.1 ± 14.4 mm. The average NRS score decreased from postoperative day 1 with 2.84 nonlinearly by 1.03 points (36.3

Objective: While long standing radiographs (LSR) represent the gold standard for preoperative alignment assessment and planning of lower limb deformity corrections, there is no consensus about the intraoperative alignment assesments (IAC) due to various limitations of the common methods. The present study introduces a radiolucent X-ray grid with integrated radiopaque lines explicitly designed for fluoroscopic IAC and evaluates its reliability in comparsion to the LSR. Methods: Patients with posttaumatic and congenital lower limb deformity surgery and preoperative LSR as well as fluoroscopic IAC utilizing the X-ray grid were retrospectively included to the study. The me-chanical axis deviation (MAD) in percentage of the maximum tibial width from the medial to the lateral in comparison between the image pairs was set as primary outcome parameter. Multiple rater and measurements determined intra- and interobserver reliabilit of both imaging methods. In addition, the effects of age, gender, body mass index (BMI), etiology, joint line convergence angle (JLCA), and extent varus or valgus deformity were analysed. Results: A total of 84 patients were finally included. The mean absolute difference of MAD between the two techniques was 7.2 +/- 0.8%. MAD between the LSR and IAC correlated at a high level (R = 0.96, p < 0.001). The agreement decreased with increasing extent of deformity (p < 0.01) and with higher devia-tion of JLCA between LSR and IAC (p < 0.01). Intra-and interobserver concordance correlation coefficient (CCC) for MAD measurements were 0.99 for both imaging techniques. Conclusion: Fluoroscopy combined with the X-ray grid method is a valid tool for intraoperative assess-ment of lower limb alignment in deformity correction surgery, and the correlation between LSR and IAC is better than in other similar techniques described in the literature. However, in case of severe coronal alignment deformity and highly divergent JLCA, the agreement between both imaging techniques decreases significantly. (C) 2022 Published by Elsevier Ltd.

Purpose: In distraction osteogenesis (DO) of long bones, new bone tissue is distracted to lengthen limbs or reconstruct bone defects. However, mechanical boundary conditions in human application such as arising forces are mainly based on limited empirical data. Our aim was the numerical determination of the callus distraction force (CDF) and the total distraction force (TDF) during DO in the tibia of adults to advance the understanding of callus tissue behavior and optimize DO procedures.Method: We implemented a mathematical model based on an animal experiment to enable the calculation of forces arising while distracting callus tissue, excluding the influence of surrounding soft tissue (muscles, skin etc.). The CDF progression for the distraction period was calculated using the implemented model and varying distraction parameters (initial gap, area, step size, time interval, length). Further, we estimated the CDF based on reported forces in humans and compared the results to our model predictions. In addition, we calculated the TDF based on our CDF predictions in combination with reported resisting forces due to soft tissue presence in human cadavers. Finally, we compared the progressions to in vivo TDF measurements for validation.Results: Due to relaxation, a peak and resting CDF is observable for each distraction step. Our biomechanical results show a non-linear degressive increase of the resting and peak CDF at the beginning and a steady nonlinear increase thereafter. The calculated resting and peak CDF in the tibial metaphysis ranged from 0.00075 to 0.0089 N and 0.22-2.6 N at the beginning as well as 20-25 N and 70-75 N at the end of distraction. The comparison to in vivo data showed the plausibility of our predictions and resulted in a 10-33% and 10-23% share of resting CDF in the total resting force for bone transport and elongation, respectively. Further, the percentage of peak CDF in total peak force was found to be 29-58% and 27-55% for bone transport and elongation, respectively. Moreover, our TDF predictions were valid based on the comparison to in vivo forces and resulted in a degressive increase from 6 to 125 N for the peak TDF and from 5 to 76 N for the resting TDF.Conclusion: Our approach enables the estimation of forces arising due to the distraction of callus tissue in humans and results in plausible force progressions as well as absolute force values for the callus distraction force during DO. In combination with measurements of resisting forces due to the presence of soft tissue, the total distraction force in DO may also be evaluated. We thus propose the application of this method to approximate the behavior of mechanical callus properties during DO in humans as an alternative to in vivo measurements.

Distraction osteogenesis (DO) is a technique that can be successfully used to treat leg length discrepancies and to reconstruct long defects of bone. By gradual distraction of the bone fragments by approximately 1 mm per day, hypervascularization and an increased bone healing potential (growth stimulus) occur. So far, DO has almost exclusively been used longitudinally to generate new biologically active bone. Chronic wounds, ulcers and osteitis, especially in the region of the foot, are always a challenge for the treating surgeon, since treatment is tedious, the outcome uncertain and associated with possible loss of the extremity. Transverse distraction osteogenesis (tDO) now uses the growth stimulus of the DO translationally to treat distally located, chronic wounds and thus leads to accelerated wound healing. At the end of the 5-week treatment, the transversely distracted fragment, located far proximal to the chronic wound, is back in its original location. The biological stimulus has a long-lasting effect, longer than the tDO itself. Further investigations into the mechanisms of action and treatment outcomes of tDO are required. If the previous results are confirmed, tDO may become a game changer and enable the limb salvage for a large proportion of findings that previously required amputation.

Die 33-jährige Patientin hatte im Alter von 8 Jahren eine rechtsseitige distale Femurfraktur erlitten. Die Patientin gibt an, rechtsseitig ein X-Bein und eine Beinlängendifferenz von 3cm zu haben. Einen Längenausgleich durch Einlagen oder Schuhausgleich trage sie nicht. Sie klagt über belastungsabhängige, diffuse Hüftund Kniegelenkschmerzen, rechtsseitigen lateralen retropatellaren Schmerz und gelegentliche Beschwerden in der unteren LWS. In der Vergangenheit sei es selten, zuletzt vor 2 Jahren, zu einer kurzen, schmerzhaften Blockade bei Beugung des rechten Kniegelenks gekommen. Die Patientin sei im Übrigen gesund; sie nehme wegen der geschilderten Beschwerden Ibuprofen nach Bedarf ein. ? Prüfungsfragen – Welche Fragen stellen Sie bei der Anamneseerhebung, und welche klinischen Untersuchungen führen Sie durch? – Welche weiterführende Diagnostik halten Sie für notwendig/ sinnvoll? Nennen Sie wichtige Parameter zur Analyse der Beingeometrie. – Nennen Sie Risikofaktoren für die patellofemorale Instabilität – Welche davon könnten bei der Patientin zutreffen? – Welche Behandlungsoption(en) schlagen Sie der Patientin vor? – Was ist bei der Operationsplanung zu bedenken? – Worüber müssen Sie neben den allgemeinen Operationsrisiken aufklären?

Background: In distraction osteogenesis (DO) of long bones, new bone tissue is formed and distracted to lengthen limbs or reconstruct bone defects. However, certain anthropometric quantities relevant for biomechanical modelling of DO are unknown, such as areas where new bone tissue is formed. We developed a novel method to facilitate the determination of these distraction areas (DA), which we applied in the tibia and fibula of adults for longitudinal and transverse DO to advance knowledge of anatomical boundary conditions. Methods: CT data sets of 21 adult human tibiae and 24 fibulae were selected for investigation. Volumetric models were created utilizing image segmentation. The DA for longitudinal DO was determined in a CAD environment using the total bone cross section in the proximal, central and distal diaphysis of the tibia and fibula. Additionally, the medullary canal area was determined in the fibula. Furthermore, we measured the total DA and medullary canal DA for transverse distraction using a longitudinally split fibula with an osteotomy length of 8, 12, 16 and 20 cm. The osteotomy plane was oriented in medial and anteromedial direction. Finally, Spearman analyses were conducted to assess the correlation between bone length and DA. Results: For longitudinal DO, the mean total DAs were 878, 535 and 482 mm(2) in the tibia and 132, 153, 124 mm(2) in the fibula for the proximal, central and distal diaphysis, respectively. Regarding transverse distraction, the mean total DAs for a medial and anteromedial osteotomy plane orientation were 962, 1423, 1868 and 2306 mm(2) as well as 925, 1387, 1844, 2279 mm(2) for an osteotomy length of 8, 12, 16 and 20 cm, respectively. Weak, positive, and non-significant correlations were observed when correlating bone length and DA in the tibia and fibula. Conclusions: Quantification of DAs and hence distracted callus tissue in DO advances anatomical knowledge and improves biomechanical modelling by adding a parameter which cannot be approximated based on bone length. (C) 2020 Elsevier GmbH. All rights reserved.

Zusammenfassung Hintergrund Bei Tibia-Osteotomien (TO) mit Marknagelfixierung kann eine minimal-invasive, prophylaktische Fasziotomie (PF) der Extensorenloge zur Prävention eines postoperativen akuten Kompartmentsyndroms (KS) erfolgen. Bislang sind keine Studien über die Effekte von TO oder PF auf spezifische Funktionen der Extensoren bekannt. Ziel der Arbeit Die Untersuchung der Funktion nach PF und TO an Patient*innen ohne präoperative funktionelle Einschränkung. Material und Methoden In 41 Fällen (28 Frauen, 13 Männer) erfolgte durchschnittlich 6,1 Jahre nach elektiver TO mit PF und Marknagelfixierung eine Befragung zur klinischen Funktion. In 23 Fällen wurden die isometrische Kraft und der „range of motion“ (ROM) der Dorsalextension (DE) des oberen Sprunggelenks (OSG) gemessen. Die Kraft wurde als Test auf klinische Relevanz mit der 10 %-Normperzentile verglichen, sowie zur Gegenseite. Ergebnisse In durchschnittlich 86 % der Fälle wurde von keinen oder geringen funktionellen Einschränkungen der Extensoren berichtetet. Die mittlere Kraft zeigte keine signifikante Abweichung von der geschlechterspezifischen 10 %-Normperzentile, aber war im Seitenvergleich auf der operierten Seite mit 16,0 ± 6,5 kgf signifikant geringer als auf der Gegenseite mit 17,5 ± 6,3 kgf (p < 0,01). Die subjektive Einschränkung der DE im OSG korrelierte deutlich negativ mit der ROM (rs = −0,46, p < 0,05). Diskussion Die Ergebnisse lassen auf eine geringe Häufigkeit subjektiv relevanter funktioneller Einschränkungen der Extensoren schließen. Die vorgefundene Kraftminderung war nicht klinisch relevant. Subjektive Einschränkungen scheinen vorrangig durch Abnahme des ROM verursacht zu sein.

Background: Three-dimensional (3D) imaging and analysis offer new possibilities in preoperative diagnostics and surgical planning. Simultaneous 3D analysis of the joint angles and the patellofemoral anatomy allow for a realistic assessment of bony pathologies in patients with patellofemoral complaints. This study aims to develop a standardized and validated assessment of the 3D patellofemoral morphology and to establish reference ranges. Methods: Thirteen patellofemoral anatomic landmarks were defined on 3D bone models of the lower limbs based on computer tomography data and evaluated regarding inter-and intra-observer variability. Further, 60 3D models of the lower limbs of young subjects without any previous knee operation/injury were assessed and rescaled reference values for relevant patellofemoral indices were obtained. Results: The mean inter-and intra-observer deviation of all landmarks was below 2.3 mm. The interobserver intraclass correlation coefficient (ICC) was between 0.8 and 1.0 and the intra-observer ICC between 0.68 and 0.99 for all patellofemoral parameters. The calculated reference ranges are: Insall-Salvati index 1.0-1.4; patella tilt 6-18 degrees; patella shift-4 to 3 mm; patella facet angle 118-131 degrees; sulcus angle 141-156 degrees; trochlear depth 3-6 mm; tibial-tuberosity to trochlear groove distance (TT-TG) 2D 14-21 mm; TT-TG 3D 11-18 mm; lateral trochlear inclination 13-23 degrees; trochlear facet angle 43-65 degrees. Conclusion: The demonstrated 3D analysis of the patellofemoral anatomy can be performed with high inter-and intra-observer correlation. Applying the obtained reference ranges and using existing 3D assessment tools for lower limb alignment, a preoperative 3D analysis and planning for complex knee procedures now is possible. (c) 2021 Elsevier B.V. All rights reserved.

Ilizarov's technology is an internationally recognized clinical treatment method for limb orthopedics, but there are many complications related to external fixation. With the development and progress of the times, the remote-control intramedullary lengthening nails had risen to prominence on the international stage as the second generation of orthomelic technology based on Ilizarov's technology. Since the first remote-control intramedullary lengthening nail appeared in the 1980s, after more than 40 years of development, there are currently more than 3 types of extension mechanisms in remote-control intramedullary lengthening nails and a mature and stable clinical treatment model has been formed during the past long-term clinical treatment and experiments, such as the End-Point-First (EPF) program proposed by Professor Peter H. Thaller in Germany. Compared with Ilizarov's technology, the remote-control intramedullary lengthening nail has obvious advantages in convenience, comfort, risk of infection, soft tissue injury, postoperative pain, and controllability of limb lengthening. This article mainly introduces the development and clinical treatment concept of remote-control intramedullary lengthening nail and the latest clinical treatment status of limb lengthening therapy abroad, hoping to provide new cognition and ideas for the further development of limb orthopedics in China.

Abstract Background Intramedullary limb lengthening has become an accepted concept in reconstructive surgery, but as yet comparative clinical studies are missing. We compared the complications and effectiveness of two types of intramedullary limb lengthening devices (ISKD®; Fitbone®). Materials and methods In a retrospective series of 278 consecutive patients with internal limb lengthening, we found 17 matching pairs in terms of predefined matching parameters (group I with ISKD® and group II with Fitbone®). The surgeries were all performed with the same technique and managed with equivalent pre- and postoperative treatment protocols. The performance of the implants was evaluated using the distraction index and the weight-bearing index. Complications were rated according to Paley's classification for external lengthening. Results The distraction index in group I (ISKD®) was 0.99 mm/day (range 0.55–1.67) and in the group II (Fitbone®) 0.55 mm/day (range 0.14–0.92) (p value = 0.001). The mean weight-bearing index differed between group I and group II from 32.0 day/cm (range 16.4–64.0) to 51.6 day/cm (25.8–95.0) (p value = 0.001). There were 17 recorded incidents in group I and 19 in group II during lengthening. Conclusion Specific technical handicaps of the two systems, such as the so-called runaway of the ISKD® and backtracking of the Fitbone® nails seem to result in different distraction index and weight-bearing index. Further comparative studies might induce technical progress in intramedullary limb lengthening. How to cite this article Thaller PH, Frankenberg F, Degen N, et al. Complications and Effectiveness of Intramedullary Limb Lengthening: A Matched Pair Analysis of Two Different Lengthening Nails. Strategies Trauma Limb Reconstr 2020;15(1):7–12.

Fragestellung: Pollerschrauben (transmedulläre Stützschrauben), dienen der Reposition von dislozierten Frakturen, Achskorrekturen und der Erhöhung der Primärstabilität bei intramedullären Implantatsystemen. Pollerschrauben werden dabei meist mittels Freihand-Methode und Röntgenwandler eingebracht, wodurch die Platzierung der Pollerschrauben deutlich von der gewollten Position abweichen kann. Wissenschaftlich wurde dabei der Einfluss auf die Erhöhung der Primärstabilität bestätigt, jedoch die Qualität der Applikation der Pollerschrauben auf die Erhöhung der Stabilität nicht umfassend untersucht.