gms | German Medical Science

Objectives: Subluxation and dislocation of adjacent joints are among the most feared adverse events of lower limb lengthening. Lengthening procedures undertaken in limbs suffering preexisting joint instability due to congenital limb deficiencies are believed to be at particular risk. However, few studies have yet investigated incidence and outcome of joint dislocations and subluxations occurring during distraction osteogenesis performed with different lengthening devices [1], [2].

Methods: Retrospective analysis of lengthening procedures of the lower limb performed between 2011–2023. Distraction osteogenesis was either conducted with an external fixator (Limb Reconstruction System™(Orthofix, Lewisville, TX, USA) in the femur; Taylor Spatial Frame (Smith&Nephew, London, UK)in the tibia) or with an intramedullary lengthening device (PRECICE^®Limb Lengthening System (NuVasive, San Diego, CA, USA)). Intramedullary lengthening devices were either inserted through an ante- or retrograde approach.

Results and conclusion: A total of 907 lengthening procedures were conducted in 533 patients (Table 1 [Tab. 1]). 175 lengthenings were simultaneously performed at the respective bilateral segments. 144 patients had 2-5 subsequent lengthening procedures (2: n=107; 3: n=25; 4: n=10; 5: n=2). Joint subluxations or dislocations occurred in 30/907 (3.3%) lengthenings in 27 patients, and were most commonly observed in femoral lengthening with an external fixator (Table 1 [Tab. 1]). The mean follow-up of this patient group was 4.3 years (1.0–12.3). The median age at surgery was 7.5 years (±11.3). 2 patients received bilateral treatment for stature lengthening, whilst 25/27 patients were treated for leg length discrepancy (LLD). Congenital femoral deficiency (10/27; 37%) and fibular hemimelia (4/27; 15%) where the predominant underlying conditions for LLD. The median preexisting LLD was 46 mm (±18.4).

There were 6/29 (21%) dislocations of the knee, 15/29 (52%) subluxations of the knee, 2/29 (7%) dislocations of the hip, 3/29 (10%) subluxations of the hip, 3/29 (10%) isolated patellar dislocations, and 1/29 (3%) talocalcaneal dislocation. In two patients, subluxation of both the knee and hip joint occurred during femoral lengthening with an external fixator. Revision surgery was required in 27/30 cases (90%), performed at a median of 119 days (±130) after the initial surgery.

Femoral lengthening procedures with an external fixator undertaken in limbs with lateral longitudinal deficiency appear to bear a great risk of knee joint subluxation and dislocation. In this patient group, distraction osteogenesis should be performed with utmost caution.