Dysplasia in the development of the hip

Intraoperative blood loss and haemoglobin drop in patients with developmental dysplasia of the hip in Jordan undergoing total hip arthroplasty

PURPOSE

Developmental dysplasia of the hip is still a prevailing secondary cause of early hip osteoarthritis in Jordan. Dysplastic coxarthrosis can result in significant and disabling hip pain with impaired patient's functionality. Due to this significant morbidity, patients ultimately need total hip arthroplasty, which offers the best functional outcome. Significant anatomical aberrances do exist in such hips as a result of old dysplasia; such pathoanatomical changes can complicate an already difficult surgery and lead to significant intraoperative blood loss and haemoglobin drop postoperatively. So, the aim of this research was to investigate on the intraoperative blood loos, and postoperative haemoglobin drop in these patients.

METHODS

A cross-sectional study design was adopted, and 162 patients with advanced hip osteoarthrosis secondary to developmental dysplasia of the hip (DDH) were studied. We studied predictors of hemoglobin drop and blood loss and linked some variables to this outcome variable using different statistical tests.

RESULTS

Our results showed a positive correlation between blood loss and BMI (r = 0.27, p = 0.73), haemoglobin drop and duration of surgery (r = 0.14, p = 0.07), length of hospital stay and duration of surgery (r = 0.25, p = 0.001). No significant differences between outcome measures (blood loss, haemoglobin drop, and duration of surgery) between males and females (p = 0.38, 0.93, 0.77 respectively). However, there was a statistically significant differences in haemoglobin drop among patients underwent general versus spinal anaesthesia (p = 0.03). additionally, there was a statistically significant association in length of hospital stay among smokers (p = 0.03), and patients who didn't prescribed anxiolytic preoperatively (p = 0.008).

CONCLUSION

Haemoglobin drop and blood loss in patients with dysplastic coxarthrosis were linked to increased preoperative BMI. Use of preoperative anxiolytics, and being non-smoker decreased the length of hospital stays. General anaesthesia was associated with more haemoglobin drop as well.

Assessment of irreducible aspects in developmental hip dysplasia by magnetic resonance imaging

BACKGROUND

The developmental dysplasia of the hip (DDH) can cause a wide range of pathological changes, and often requires surgical treatment. Preoperative evaluation is very important for DDH. We aimed to assess the diagnostic capability of magnetic resonance imaging (MRI) for irreducible aspects preventing hip reduction in DDH.

METHODS

A total of 39 pediatric patients who received DDH evaluation in pediatric orthopedics from January 2015 to December 2019 were included. The samples included 4 cases of bilateral DDH and 35 cases of unilateral DDH, a total of 43 hip joint samples. All patients underwent surgical treatment, pathological examination and MRI of hip joint.

RESULTS

With pathological results or intraoperative findings as the gold standard, the sensitivity and specificity of MRI were 90.3% and 83.3% for the affected labrum, 92% and 83.3% for thickening of the round ligament, 90.0% and 91.3% for atrophy of the iliopsoas muscle, and 100% and 100% for fibrofatty pulvinar tissue and joint effusion, respectively.

CONCLUTIONS

The MRI showed an extraordinary capability of detecting these irreducible factors and helped surgeon choose the appropriate treatment strategies.

Prediction of mechanical behavior of cartilaginous infant hips in pavlik harness: A subject-specific simulation study on normal and dysplastic hips

In dysplastic infant hips undergoing abduction harness treatment, cartilage contact pressure is believed to have a role in therapeutic cartilage remodeling and also in the complication of femoral head avascular necrosis. To improve our understanding of the role of contact pressure in the remodeling and the complication, we modeled cartilage contact pressure in cartilaginous infant hips undergoing Pavlik harness treatment. In subject-specific finite element modeling, we simulated contact pressure of normal and dysplastic hips in Pavlik harness at 90° flexion and gravity-induced abduction angles of 40°, 60° and 80°. We demonstrated that morphologies of acetabulum and femoral head both affected contact pressure distributions. The simulations showed that in Pavlik harness, contact pressure was mainly distributed along anterior and posterior acetabulum, leaving the acetabular roof only lightly loaded (normal hip) or unloaded (dysplastic hip). From a mechanobiological perspective, these conditions may contribute to therapeutic remodeling of the joint in Pavlik harness. Furthermore, contact pressure increased with the angle of abduction, until at the extreme abduction angle (80°), the lateral femoral head also contacted the posterior acetabular edge. Contact pressure in this area could contribute to femoral head avascular necrosis by reducing flow in femoral head blood vessels. The contact pressure we simulated can plausibly account for both the therapeutic effects and main adverse effect of abduction harness treatment for developmental dysplasia of the hip. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

Hip Joint Contact Pressure Distribution During Pavlik Harness Treatment of an Infant Hip: A Patient-Specific Finite Element Model

Developmental dysplasia of the hip (DDH) in infants under 6 months of age is typically treated by the Pavlik harness (PH). During successful PH treatment, a subluxed/dislocated hip is spontaneously reduced into the acetabulum, and DDH undergoes self-correction. PH treatment may fail due to avascular necrosis (AVN) of the femoral head. An improved understanding of mechanical factors accounting for the success/failure of PH treatment may arise from investigating articular cartilage contact pressure (CCP) within a hip during treatment. In this study, CCP in a cartilaginous infant hip was investigated through patient-specific finite element (FE) modeling. We simulated CCP of the hip equilibrated at 90 deg flexion at abduction angles of 40 deg, 60 deg, and 80 deg. We found that CCP was predominantly distributed on the anterior and posterior acetabulum, leaving the superior acetabulum (mainly superolateral) unloaded. From a mechanobiological perspective, hypothesizing that excessive pressure inhibits growth, our results qualitatively predicted increased obliquity and deepening of the acetabulum under such CCP distribution. This is the desired and observed therapeutic effect in successful PH treatment. The results also demonstrated increase in CCP as abduction increased. In particular, the simulation predicted large magnitude and concentrated CCP on the posterior wall of the acetabulum and the adjacent lateral femoral head at extreme abduction (80 deg). This CCP on lateral femoral head may reduce blood flow in femoral head vessels and contribute to AVN. Hence, this study provides insight into biomechanical factors potentially responsible for PH treatment success and complications.