Birmingham Hip Resurfacing - Literature Review

Demographics for X-Ray, Oswestry, McMinn, and Overall McMinn cohorts
Patients in the Overall McMinn cohort were 70.6% men and 29.4% women, ages 13-86 years (average 53.1 years). The primary diagnosis was osteoarthritis in 75.0%, dysplasia in 15.8%, avascular necrosis in 4.1%, inflammatory arthritis in 2.4%, and “other” in 2.7% (Table 4).

Demographics for X-Ray/Oswestry combined cohort
Patients in the survivorship study (X-ray/Oswestry combined cohort) ranged in age from 13.4 to 86.5 years (mean 53 years); 72% of the patients are male, and 28% are female. Of the 1,626 BHR procedures in this cohort, 1,499 (92%) were performed in patients < 65 years old, and 127 (8%) were performed in patients > 65 years old.

Diagnostic Indications for Unilateral and Bilateral procedures in X-Ray/Oswestry combined cohort
One thousand one hundred and eleven (1,111) of the X-ray/Oswestry combined cohort cases (68%) were unilateral procedures and 515 (32%) were bilateral procedures. The indication for the majority of cases was osteoarthritis. Table 5 provides the breakdown of unilateral and bilateral cases by indication.

Some of the patients with bilateral hip replacements were included in different groups depending on when the second hip procedure was performed (Table 6).

* Patients with bilateral hip replacements with the contralateral hip not included in the first hip replacement’s evaluation cohort.
** Number of patients equals unilateral + bilateral + singles
*** Number of hips equals unilateral + (2 x bilateral) + singles

Demographics: Literature References
The study published by D'Antonio et al. reported findings from a multicenter study conducted at 22 investigational sites; the study published by Garino was conducted at 11 investigational sites (Table 7).

D’Antonio et al. reported the indication for THR as osteoarthritis in 399/514 procedures (77.6%) and avascular necrosis in 82/514 procedures (16%) (Table 8).

Patient Accounting
The follow-up rates for the Combined X-Ray / Oswestry Cohort, upon which the effectiveness analyses were performed, at the 1-year, 2-year, 3-year, 4-year, and 5-year postoperative evaluation time points were 76.6%, 77.3%, 88.1%, 88.6%, and 90.8%, respectively. There were 546 procedures (hips) evaluated at 5 years in this cohort (Table 9).

¹ Note that for the Survivorship data the “year 1” data is starting from day 1 and the “year 2” data is starting from day 366, etc. but for the OSHIP scores, the “year 1” data was collected between day 366-730, the “year 2” data was collected between day 731-1095, etc.
² Evaluated by OSHIP score.
³ OSHIP score was available for one hip that was revised shortly after the 5-year follow-up interval, OSHIP data available on 112/119 (94.1%) of hips surviving to 5 years.
⁴ Evaluated by X-Ray.
⁵ The follow-up of those who had baseline OSHIP scores (+base) and those without baseline OSHIP scores (-base).
⁶ Note that there were 2 revisions in the x-ray cohort at >5 years.
⁷ There were 5 cases in the McMinn cohort whose implantations were performed prior to 4/02. These cases should have been part of the Oswestry cohort, but for unknown reasons were not. Therefore, unlike the majority of the McMinn cohort, some of these 5 cases have longer term follow-up.
⁸ The expected and evaluated values in each interval include hips with a recorded OSHIP even if the subject died or was revised during the interval.

For the unilateral patients in the X-Ray / Oswestry combined cohort, the follow-up rates at the 1-year, 2-year, 3- year, 4-year, and 5-year postoperative evaluation time points were 75.7%, 76.6%, 88.2%, 88.4%, and 91.1%, respectively (Table 10).

Accounting identified in the literature references were as provided in Table 11.

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2/4/2007

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