THE BIOMECHANICAL ANALYSIS OF PELVIC OSTEOTOMIES APPLIED FOR DDH TREATMENT IN PEDIATRIC PATIENTS

OBJECTIVE

The aim: This article aimed to evaluate biomechanical changes during the most commonly used pelvic osteotomies (Salter, Dega, Pemberton) for DDH treatment in pediatric patients.

PATIENTS AND METHODS

Materials and methods: Virtual pelvic models of 2- and 6-years old patients were created, material properties were assigned, pelvic osteotomies were simulated and biomechanical changes were evaluated using finite element analysis (FEA).

RESULTS

Results: It was revealed that the patient's age impacts pelvic bones and cartilage density (in younger patients the pelvic elements are more pliable - p<0.05). Stress distribution after each of the abovementioned pelvic osteotomy was assessed in 2- and 6-year-old patients' pelvic models. The new term "restriction point" was introduced, which means a place where restriction of acetabular deformity correction occurs.

CONCLUSION

Conclusions: It was found that there are no purely reshaping and reorientation pelvic osteotomies as previously believed; the pelvic ring acts as a unit in carrying out the applied load. Biomechanical overload of triradiate cartilage during Salter osteotomy in 2-year-old patients and in 2- and 6-year-old patients during Pemberton osteotomy was revealed; overload of the posterior cortical layer in the greater sciatic notch in 2-years old patient during Dega osteotomy was revealed.

Salter pelvic osteotomy for the treatment of Developmental Dysplasia of the Hip: assessment of postoperative results and risk factors

BACKGROUND

If non-surgical treatment of Developmental Dysplasia of the Hip (DDH) fails or if DDH is late-detected, surgery is necessary. Salter pelvic osteotomy (SPO) is an effective surgical option for such cases.

OBJECTIVES

To study the results after SPO; to evaluate risk factors; to reveal radiological parameters that may correlate with results.

METHODS

Results analysis in 17 patients (22 hips). Risk factors included those that do not depend on the surgeon (patient's age, value of the acetabular index (AI) preoperatively, DDH Tonnis grade) and those that depend on the surgeon (amount of AI correction). To radiological parameters which may correlate with the amount of AI correction we referred distance "d" and the lateral rotation angle.

RESULTS

SPO allows performing AI correction in ranges 24.1 ± 6.5°. Excellent and good clinical results were obtained in 95.5% of patients; excellent and good radiological results in 86.4% of patients. Risk factors that do not depend on the surgeon were older patient's age and higher preoperative AI values (p <0.05). The risk factor that depends on the surgeon was the amount of AI correction (p <0.05). The distance "d" was recognized as a radiological parameter that may indicate sufficient AI correction (p <0.05).

CONCLUSION

In older patients with a higher preoperative AI value the results will be predictably worse. The surgeon may influence the result with a greater amount of AI correction (which may also be indicated radiologically by the distance "d" values).

LEVEL OF EVIDENCE

IV, therapeutic, case series.

Simulation of pelvic osteotomies applied for DDH treatment in pediatric patients using piglet models

BACKGROUND

Developmental dysplasia of the hip (DDH) is a common hip joint pathology seen in the pediatric orthopedist's practice. Pelvic osteotomies are the reliable surgical option for DDH treatment in walking patients, and 3 osteotomies (Salter, Dega and Pemberton) are widely used in patients under 6 years of age. Plastic changes in hinge points occur during iliac fragment movement, after the performed osteotomy. The locations of these points are described in the literature, but some debate still exists about their true positions.

OBJECTIVES

To reveal hinge point locations during a simulation of pelvic osteotomies on biological models.

MATERIAL AND METHODS

Eighteen piglet pelvis complexes were obtained and separated according to their age. Pelvic osteotomies were simulated, and bone changes were assessed on computed tomography (CT) scans after the performed surgeries.

RESULTS

No bone changes were found after Salter osteotomy in younger piglets, while contralateral pubic bone metaphyseal fractures were found in older animals. After Pemberton osteotomy, greenstick fractures in iliac and pubic bones metaphyses in the triradiate cartilage area were revealed in younger and older piglets. After Dega osteotomy, a posterior medial cortical layer fracture of the uncut iliac bone in the greater sciatic notch was found in all piglets. In older piglets, an additional hinge point was detected in the ipsilateral pubic bone metaphysis.

CONCLUSION

It was found that the age of the piglets has an impact on hinge point number and location, and this may be explained by an age-related decrease in pelvic bone and cartilage plasticity. The results of this study may help surgeons to decrease the number of preventable complications during pelvic osteotomies.