TY - JOUR
T1 - Superior bone fixation of conical compared with hemispherical trapezial cup design
T2 - an experimental radiostereometry study
AU - Stilling, Maiken
AU - Dremstrup, Lene
AU - Hansen, Torben Bæk
AU - Thillemann, Janni Kjærgaard
N1 - Publisher Copyright:
© 2023, The Author(s).
PY - 2023/11
Y1 - 2023/11
N2 - Purpose: The most used cup designs for trapeziometacarpal (TMC) arthroplasty are of hemispherical and conical geometrical shape. Using a validated pig bone model, we compared the bone fixation using radiostereometry (RSA). Methods: Twenty saddle-shaped pig forefoot bones were prepared with insertion of bone markers and reaming. Hemispherical Type T cups (Beznoska, Kladno, Czech Republic) (N = 10) and conical Moovis cups (Stryker, Pusignan, France) (N = 10) of 9-mm diameter were inserted press-fit. The bones were fixed in cement blocks for stability, and the cups were loaded in a motorized test stand. First, a low-pressure cyclic load test (0—150N) with 130 compression cycles was performed. Next, a push-in test of progressive loads with 50N increments (range: 150–900N) was applied until a visual change in cup position appeared. Cup migration was evaluated with RSA after every new load application. Cup failure was defined as total translation > 0.5 mm between two load applications. Results: Both cup types tolerated a compression load of 450 N without failure. Beyond this load level, the total translation cup migration of mean 0.20 mm (95% CI 0.11; 0.30) for the Type T group was higher than mean 0.10 mm (95% CI 0.06; 0.15) of the Moovis group (p = 0.046). The Hazard ratio for failure was 0.52 (95% CI 0.12; 2.17) (p = 0.37), indicating that the risk of failure was two-fold higher in the Type T group. Conclusion: We conclude that conical TMC cups have superior fixation as compared to hemispherical cups above a loading level of 450 N, which correspond to a 3.8 kg tip-pinch. In a clinical perspective, based on the fixation strength of both cup types, it seems safe to allow light-load activities of daily living such as buttoning a shirt and using a key shortly after surgery and until sufficient osseointegration is achieved.
AB - Purpose: The most used cup designs for trapeziometacarpal (TMC) arthroplasty are of hemispherical and conical geometrical shape. Using a validated pig bone model, we compared the bone fixation using radiostereometry (RSA). Methods: Twenty saddle-shaped pig forefoot bones were prepared with insertion of bone markers and reaming. Hemispherical Type T cups (Beznoska, Kladno, Czech Republic) (N = 10) and conical Moovis cups (Stryker, Pusignan, France) (N = 10) of 9-mm diameter were inserted press-fit. The bones were fixed in cement blocks for stability, and the cups were loaded in a motorized test stand. First, a low-pressure cyclic load test (0—150N) with 130 compression cycles was performed. Next, a push-in test of progressive loads with 50N increments (range: 150–900N) was applied until a visual change in cup position appeared. Cup migration was evaluated with RSA after every new load application. Cup failure was defined as total translation > 0.5 mm between two load applications. Results: Both cup types tolerated a compression load of 450 N without failure. Beyond this load level, the total translation cup migration of mean 0.20 mm (95% CI 0.11; 0.30) for the Type T group was higher than mean 0.10 mm (95% CI 0.06; 0.15) of the Moovis group (p = 0.046). The Hazard ratio for failure was 0.52 (95% CI 0.12; 2.17) (p = 0.37), indicating that the risk of failure was two-fold higher in the Type T group. Conclusion: We conclude that conical TMC cups have superior fixation as compared to hemispherical cups above a loading level of 450 N, which correspond to a 3.8 kg tip-pinch. In a clinical perspective, based on the fixation strength of both cup types, it seems safe to allow light-load activities of daily living such as buttoning a shirt and using a key shortly after surgery and until sufficient osseointegration is achieved.
KW - Conical cup
KW - Cup fixation
KW - Hemispherical cup
KW - Radiostereometry
KW - Trapeziometacarpal arthroplasty
KW - Trapeziometacarpal osteoarthritis
UR - http://www.scopus.com/inward/record.url?scp=85178234126&partnerID=8YFLogxK
U2 - 10.1186/s40634-023-00692-y
DO - 10.1186/s40634-023-00692-y
M3 - Journal article
C2 - 38032446
AN - SCOPUS:85178234126
SN - 2197-1153
VL - 10
JO - Journal of Experimental Orthopaedics
JF - Journal of Experimental Orthopaedics
IS - 1
M1 - 127
ER -