Long-term results show stronger pinch strength after combined thumb arthroplasty, fusion
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BOSTON — Long-term results showed significantly stronger pinch strength after patients with metacarpophalangeal arthritis underwent carpometacarpal arthroplasty with metacarpophalangeal fusion vs. carpometacarpal arthroplasty alone.
These conclusions, which Carissa C. Dock, MS, a third-year medical study at University of Minnesota, presented at the American Society for Surgery of the Hand Annual Meeting, here, stemmed from a retrospective chart review of long-term results of 80 patients and 112 operated thumbs. The average follow-up was 5.9 years.
“Patients who were treated with an [metacarpophalangeal] MP fusion at the time of [carpometacarpal] CMC arthroplasty had statistically and clinically significantly stronger pinch long term. They had equivalent satisfaction to those who had only a CMC arthroplasty and they had only a 1.7% chance of hardware removal,” Dock said.
Dock and colleagues hypothesized patients who underwent MP fusion at the time of CMC arthroplasty due to diagnoses of MP hyperextension greater than 30°, thenar atrophy or MP arthritis (60 procedures), would have greater long-term functional pinch strength compared with patients who underwent CMC arthroplasty alone (52 procedures) or compared with patients’ unaffected unoperated side. Procedures were performed between January 2006 and November 2020.
“The gender distribution was approximately 75% female with the majority of the patients being between 60 and 79 years of age,” Dock said, noting 11 patients in the CMC/MP fusion group had all three diagnoses of MP hyperextension, thenar atrophy and MP arthritis.
Outcomes measures used included pinch strength, QuickDASH, VAS scores and patient satisfaction, Dock said.
MP fusions were performed with radially sided and ulnar-sided EasyClip staples (Stryker) and trapezial bone graft, while the CMC arthroplasties were performed with trapezial excision, cadaveric interpositional fascia lata graft and abductor pollicis longus suspension sling, according to the abstract.
The abstract showed pinch strength was significantly stronger in patients after CMC arthroplasty with MP fusion at 12.7 pounds vs. in patients with CMC arthroplasty alone at 10.9 pounds.
When researchers compared pinch strength values in the CMC arthroplasty group with the unoperated side — 10.9 lbs. vs. 10.8 lbs. — the difference was not significant. However, researchers identified a significant difference in pinch strength values when they compared patients who had CMC arthroplasty and MP fusion (12.7 lbs.) with patients’ unoperated side (10.8 lbs.).
According to the abstract, long-term postoperative QuickDASH and VAS scores were similar between treatment groups. Patients in the CMC group had QuickDASH and VAS values of 11.8 and 0.60, respectively. Patients in the CMC/MP fusion group had QuickDASH and VAS values of 10.8 and 0.53, respectively, according to the abstract.
“The patient-reported outcomes revealed similar measures across both groups. Complications were also similar across both groups,” Dock said. “[There] was only one instance of hardware removal in a total of 60 patients undergoing MP fusion. This is because placing those EasyClip staples on the radial and ulnar planes avoids irritation of the extensor mechanism.”
She said, “This expands the criteria for CMC/MP fusion to include those patients who have moderate to severe thenar atrophy.”
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Dock C, et al. Paper 57. Presented at: American Society for Surgery of the Hand Annual Meeting; Sept. 29-Oct. 1, 2022; Boston.
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