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Clinical feedback to surgeons may decrease acetabular cup malpositioning
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Surgeons who receive clinical feedback about their performance after hip resurfacing or total hip arthroplasty may significantly improve acetabular cup positioning, according to a recently presented study.
A team of seven surgeons at Massachusetts General Hospital in Boston found fewer incidences of acetabular cup malpositioning when they collected information and studied radiographs from their previous surgeries and used that data to improve their surgical methods.
“If each individual surgeon got the results, we improved significantly without doing anything else,” Henrik Malchau, MD, said during his presentation at the 12th EFORT Congress 2011. “No navigation, no nothing, just feeding back the surgeon.”
Two sets of patients
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Malchau and his colleagues studied 2,061 patients who underwent total hip arthroplasties (THAs) or hip resurfacings performed by seven surgeons between 2004 and 2008. Each patient had AP pelvis and cross-table lateral radiographs. The surgeons used computer software to measure the cup inclination and version angles from the radiographs. The team set the acceptable ranges of 30° to 45° for abduction and 5° to 25° for version. After studying the results, the surgeons performed THA or hip resurfacing on 385 patients from January 2009 to June 2010.
The results from the second set of patients were compared to the first cohort to determine whether fewer malpositions occurred after the surgeons received clinical feedback. In the first set of patients, 62% of acetabular cups were within the acceptable abduction range, 79% were within the acceptable version range and 49% were within acceptable ranges for both angles. In the second set of patients, 72% were within the abduction range and 65% were within the version range. However, the investigators found that the accuracy of the acetabular cup position for both angles significantly increased to 56%.
Surgeon volume
The team also conducted a univariate and multivariate analysis on the results. In the univariate analysis, low-volume surgeons had a higher risk of malpositioned acetabular cups. The researchers also discovered that a higher number of obese patients had malpositioned acetabular components.
In the multivariate analysis, low-volume surgeons experienced a two-fold increased risk for malposition using the anterolateral position and a six-fold increase risk when they used a minimally invasive approach compared with the posterolateral approach. Patients older than 30 years had a 1.3% increased risk of malpositioning. In addition, Malchau noted that patients with a body mass index greater than 30 showed a slightly increased risk of a malpositioned cup.
Surgical complications recorded in the study included fractures of the polyethylene liner in patients with metal-on-polyethylene cups and osteolysis, said Malchau.
“The take-home message would be, we need to improve our position, have more focus on how we are doing and less focus on new implants,” Malchau said. – by Renee Blisard
Reference:
- Bragdon C, Doerner M, Callanan M. Cup positioning in total hip arthroplasty improves with clinical feedback. Paper #1693. Presented at the 12th EFORT Congress 2011. June 1-4. Copenhagen.
- Henrik Malchau, MD, can be reached at Massachusetts General Hospital, 55 Fruit St., GRJ 1126, Boston, MA 02114; 617-726-3866; email: hmalchau@partners.org.