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Association between changes in global femoral offset after total hip arthroplasty and function, quality of life, and abductor muscle strength. A prospective cohort study of 222 patients.

Mahmood SS, Mukka SS, Crnalic S, Wretenberg P, Sayed-Noor AS - Acta Orthop (2015)

Bottom Line: These patients were divided into 3 groups according to the postoperative global FO of the operated hip compared to the contralateral hip, as measured on plain radiographs: the decreased FO group (more than 5 mm reduction), the restored FO group (within 5 mm restoration), and the increased FO group (more than 5 mm increment).All 3 groups improved (p < 0.001).When we adjusted these results with possible confounding factors, only global FO reduction was statistically significantly associated with reduced abductor muscle strength.

View Article: PubMed Central - PubMed

Affiliation: a Department of Surgical and Perioperative Sciences (Orthopedics) , Sundsvall and Norrland University Hospitals, Umeå University , Stockholm , Sweden.

ABSTRACT

Background and purpose: There is no consensus on the association between global femoral offset (FO) and outcome after total hip arthroplasty (THA). We assessed the association between FO and patients' reported hip function, quality of life, and abductor muscle strength.

Patients and methods: We included 250 patients with unilateral hip osteoarthritis who underwent a THA. Before the operation, the patient's reported hip function was evaluated with the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index and quality of life was evaluated with EQ-5D. At 1-year follow-up, the same scores and also hip abductor muscle strength were measured. 222 patients were available for follow-up. These patients were divided into 3 groups according to the postoperative global FO of the operated hip compared to the contralateral hip, as measured on plain radiographs: the decreased FO group (more than 5 mm reduction), the restored FO group (within 5 mm restoration), and the increased FO group (more than 5 mm increment).

Results: All 3 groups improved (p < 0.001). The crude results showed that the decreased FO group had a worse WOMAC index, less abductor muscle strength, and more use of walking aids. When we adjusted these results with possible confounding factors, only global FO reduction was statistically significantly associated with reduced abductor muscle strength. The incidence of residual hip pain and analgesics use was similar in the 3 groups.

Interpretation: A reduction in global FO of more than 5 mm after THA appears to have a negative association with abductor muscle strength of the operated hip, and should therefore be avoided.

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Related in: MedlinePlus

The global FO was measured by addition of the distance between the longitudinal axis of the femur and the center of the femoral head (A1) and the distance from the center of the femoral head to a perpendicular line passing through the medial edge of the ipsilateral teardrop point of the pelvis (B1). The measurement was repeated bilaterally to compare the global FO of the operated side (A1 + B1) to that of the unoperated hip (A + B).
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Figure 0001: The global FO was measured by addition of the distance between the longitudinal axis of the femur and the center of the femoral head (A1) and the distance from the center of the femoral head to a perpendicular line passing through the medial edge of the ipsilateral teardrop point of the pelvis (B1). The measurement was repeated bilaterally to compare the global FO of the operated side (A1 + B1) to that of the unoperated hip (A + B).

Mentions: The global FO was measured by adding the distance between the longitudinal axis of the femur and the center of the femoral head to the distance from the center of the femoral head to a perpendicular line passing through the medial edge of the ipsilateral teardrop point of the pelvis (Figure 1). The measurement was repeated bilaterally to compare the global FO of the operated side to that of the nonoperated side. A positive value was used when the FO of the operated hip was greater than that of the contralateral side, while a negative value indicated the opposite. Measurements were calibrated to a 30-mm radiopaque standardized metal sphere or prosthetic head (32 mm) to assess the degree of magnification. A 1-mm precision scale was used. 1 independent investigator (SaSM) performed the radiological measurements to ensure objectivity.


Association between changes in global femoral offset after total hip arthroplasty and function, quality of life, and abductor muscle strength. A prospective cohort study of 222 patients.

Mahmood SS, Mukka SS, Crnalic S, Wretenberg P, Sayed-Noor AS - Acta Orthop (2015)

The global FO was measured by addition of the distance between the longitudinal axis of the femur and the center of the femoral head (A1) and the distance from the center of the femoral head to a perpendicular line passing through the medial edge of the ipsilateral teardrop point of the pelvis (B1). The measurement was repeated bilaterally to compare the global FO of the operated side (A1 + B1) to that of the unoperated hip (A + B).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4940589&req=5

Figure 0001: The global FO was measured by addition of the distance between the longitudinal axis of the femur and the center of the femoral head (A1) and the distance from the center of the femoral head to a perpendicular line passing through the medial edge of the ipsilateral teardrop point of the pelvis (B1). The measurement was repeated bilaterally to compare the global FO of the operated side (A1 + B1) to that of the unoperated hip (A + B).
Mentions: The global FO was measured by adding the distance between the longitudinal axis of the femur and the center of the femoral head to the distance from the center of the femoral head to a perpendicular line passing through the medial edge of the ipsilateral teardrop point of the pelvis (Figure 1). The measurement was repeated bilaterally to compare the global FO of the operated side to that of the nonoperated side. A positive value was used when the FO of the operated hip was greater than that of the contralateral side, while a negative value indicated the opposite. Measurements were calibrated to a 30-mm radiopaque standardized metal sphere or prosthetic head (32 mm) to assess the degree of magnification. A 1-mm precision scale was used. 1 independent investigator (SaSM) performed the radiological measurements to ensure objectivity.

Bottom Line: These patients were divided into 3 groups according to the postoperative global FO of the operated hip compared to the contralateral hip, as measured on plain radiographs: the decreased FO group (more than 5 mm reduction), the restored FO group (within 5 mm restoration), and the increased FO group (more than 5 mm increment).All 3 groups improved (p < 0.001).When we adjusted these results with possible confounding factors, only global FO reduction was statistically significantly associated with reduced abductor muscle strength.

View Article: PubMed Central - PubMed

Affiliation: a Department of Surgical and Perioperative Sciences (Orthopedics) , Sundsvall and Norrland University Hospitals, Umeå University , Stockholm , Sweden.

ABSTRACT

Background and purpose: There is no consensus on the association between global femoral offset (FO) and outcome after total hip arthroplasty (THA). We assessed the association between FO and patients' reported hip function, quality of life, and abductor muscle strength.

Patients and methods: We included 250 patients with unilateral hip osteoarthritis who underwent a THA. Before the operation, the patient's reported hip function was evaluated with the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index and quality of life was evaluated with EQ-5D. At 1-year follow-up, the same scores and also hip abductor muscle strength were measured. 222 patients were available for follow-up. These patients were divided into 3 groups according to the postoperative global FO of the operated hip compared to the contralateral hip, as measured on plain radiographs: the decreased FO group (more than 5 mm reduction), the restored FO group (within 5 mm restoration), and the increased FO group (more than 5 mm increment).

Results: All 3 groups improved (p < 0.001). The crude results showed that the decreased FO group had a worse WOMAC index, less abductor muscle strength, and more use of walking aids. When we adjusted these results with possible confounding factors, only global FO reduction was statistically significantly associated with reduced abductor muscle strength. The incidence of residual hip pain and analgesics use was similar in the 3 groups.

Interpretation: A reduction in global FO of more than 5 mm after THA appears to have a negative association with abductor muscle strength of the operated hip, and should therefore be avoided.

Show MeSH
Related in: MedlinePlus