Proximal femoral changes related to bisphosphonate use and looser zones in hypophosphatemic osteomalacia: dual-energy X-ray absorptiometry findings

Total hip arthroplasty for treatment of femoral neck fracture due to hypophosphatemic osteomalacia: a retrospective case series with mean follow-up of five years

BACKGROUND

To retrospectively characterize the clinical characteristics and efficacy of total hip arthroplasty and the important factors needing attention in hypophosphatemic osteomalacia (HO) patients with hip involvement.

PATIENTS AND METHODS

We performed a review of seven patients (two women and five men) referred to our clinic with a final diagnosis of HO who received total hip arthroplasty between 2010 and 2018. Five patients (Group 1) received proper medical management with or without aetiologic therapy, while the other two patients (Group 2) did not receive due to misdiagnosis. The mean follow-up duration was 5.1 ± 2.0 years.

RESULTS

The patients in Group 1 had significant relief of pain and improved laboratory results. The mean Harris Hip Score of Group 1 increased from 44.2 ± 6.0 to 94.0 ± 3.0, and the mean VAS score decreased from 8.8 ± 0.4 to 1.8 ± 0.7. However, the progressive extensive pain score in Group 2 had no obvious improvement, with the Harris Hip Score increasing from 45.5 ± 0.5 to 60 ± 28.0 and the VAS score decreasing from 9.0 ± 1.0 to 6.5 ± 2.5.

CONCLUSION

THA appears to be an effective method for hip arthritis or joint deformities resulting from hypophosphatemic osteomalacia. A satisfactory outcome of the surgery depends on the early etiological identification, the treatment of hypophosphatemia, a careful operation, and the operative strategies, as well as proper medical treatment.

Adult rheumatologic features, treatment and complications of X-linked hypophosphatemia

X-linked hypophosphatemia (XLH) is a rare genetic phosphate disorder caused mainly by PHEX mutations. Unlike for children, knowledge of the disease's manifestations in adults is limited. Musculoskeletal symptoms are the main feature of the disease in young adults associated with a heavy burden on patients' life. They include fractures and pseudofractures, pain, joint stiffness, osteoarthritis, enthesopathies, and muscle weakness, eventually leading to impaired quality of life. Conventional treatment with phosphate supplements and vitamin D analogs is indicated in symptomatic patients. Appropriate rehabilitation is also a key to the management of the disease to improve physical function and decrease pain, stiffness, and fatigue. Regarding the incidence and consequences of musculoskeletal features in XLH, all patients should be assessed by a bone disease specialist and, if necessary, managed by a multidisciplinary team.

Detection of Atypical Femur Fractures

The 2019 International Society for Clinical Densitometry (ISCD) Position Development Conference Task Force for monitoring with dual-energy X-ray absorptiometry (DXA) identified detection of atypical femur fractures (AFFs) as an important topic and established this working group to answer key questions in this area. The authors conducted a systematic review of the literature and deliberated on proposed ISCD positions, which were then reviewed by an external expert panel and vetted at the 2019 ISCD Position Development Conference in Kuala Lumpur on March 23, 2019. This paper summarizes the final ISCD positions and the rationale for supporting these positions. Default-length femur imaging or extended-length femur imaging as well as full-length femur imaging (FFI), both single-energy and dual-energy scans, by DXA can detect abnormalities in the spectrum of AFF. It is important to visually inspect all DXA scans of the hip and femur, and report on findings of focal periosteal and endosteal thickening at the lateral cortex (grade: Good, A, W). FFI is the preferred DXA scan mode for detecting abnormalities in the spectrum of AFF. The FFI report should state the absence or presence of abnormalities in the spectrum of AFF. If focal thickening is present on the lateral cortex, the report should state whether a lucent line is seen (grade: Fair, C, W). The ISCD recommends considering the use of bilateral FFI in patients who are currently or have been in the past year on potent antiresorptive therapy (ie, oral or intravenous bisphosphonate or subcutaneous denosumab therapy) for a cumulative period of 3 or more years, especially those on long-term glucocorticoid therapy (grade: Fair, B, W). More research is needed to determine the role of repeat testing and the optimal time interval for follow-up DXA scans, whether an automated measuring tool would perform better than visual inspection, whether FFI would change patient management and outcomes, and the cost-effectiveness of FFI.