Monostotic Paget's disease of the femur: a diagnostic challenge and an overlooked risk

'Bone within bone appearance' in a pathological fracture

A 60-year-old man presented to our hospital with complaints of pain and deformity on his right thigh for the past 2 days following a history of accidental slip and fall. Radiological investigations suggested a pathological type 2 Seinsheimer subtrochanteric fracture of the right femur with a 'bone within bone' appearance, which posed a diagnostic dilemma as this radiological appearance is seen in a spectrum of conditions. Radiographic skeletal survey failed to identify a similar appearance elsewhere in the body. Laboratory investigations pointed in favour of bone mineral disease, and histopathological examination of the bone narrowed it down to Paget's disease. The fracture was fixed with a contralateral distal femur locking compression plate. The fracture site failed to show signs of union until 6 months postsurgery and hence the patient was advised for grafting procedure. The patient deferred surgery and remains without major complications until 18 months of follow-up.

Bone turnover markers in Paget's disease of the bone: A Systematic review and meta-analysis

The aim of this systematic review and meta-analysis is to study the utility of the commonly used bone turnover markers in evaluating disease activity in patients with Paget's disease of bone before and after treatment with bisphosphonates. We found good correlation between the bone turnover marker concentrations and disease activity assessed by bone scintigraphy.

INTRODUCTION

Paget's disease of bone is a common skeletal disorder of the elderly. Bone turnover marker concentrations are used for diagnosis and follow-up. We aimed to compare the available bone turnover markers and determine their utility in assessing disease activity when compared to quantitative bone scintigraphy.

METHODS

We conducted a systematic review and meta-analysis searching MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and Scopus. We evaluated total alkaline phosphatase (total ALP), bone-specific alkaline phosphatase (bone ALP), procollagen type 1 amino-terminal propeptide (P1NP), serum, and urine C-terminal telopeptide (uCTx and sCTx, respectively), and urine N-terminal telopeptide (uNTx). The main outcome of interest was the correlation of disease activity with concentrations of bone turnover markers in Paget's disease patients before and after treatment with bisphosphonates. Correlation coefficients were pooled across studies using the random effects model.

RESULTS

We included 17 observational studies and one trial reporting on 953 patients. Prior to treatment, all studied bone turnover markers had moderate to strong correlation with scintigraphic indices (correlation coefficients ranging from 0.58 to 0.80) with no statistically significant difference between the bone turnover markers overall (p = 0.08). P1NP, uNTx, and bone ALP tend to have higher correlation with scintigraphy. After starting treatment with bisphosphonate, there was moderate to strong correlation with disease activity with all markers except bone ALP (correlation coefficients ranging from 0.43 to 0.70).

CONCLUSION

The findings of this meta-analysis suggest the Paget's disease activity is best monitored by following P1NP levels. However, total ALP, bone ALP, and uNTx are good alternatives as markers of disease activity in untreated patients. Total ALP and uNTx can be useful in following patients with Paget's disease after treatment if P1NP is not available. Clinicians, however, should take availability, cost, and the presence of liver disease into consideration when deciding which bone turnover marker is most appropriate when evaluating patients with Paget's disease.