Outcome of extensive varus and valgus stem alignment in short-stem THA: clinical and radiological analysis using EBRA-FCA.
BACKGROUND
The principle of implanting a calcar-guided short stem consists of an individual alignment alongside the medial calcar providing the ability of reconstructing varus and valgus anatomy in a great variety. However, still, there are broad concerns about the safety of extensive varus and valgus positioning in regard to stability, bony alterations, and periprosthetic fractures.


METHODS
216 total hip arthroplasties using a calcar-guided short stem (optimys, Mathys Ltd.) in 162 patients were included. Depending on postoperative CCD angle, hips were divided into five groups (A-E). Varus- and valgus tilt and axial subsidence were assessed by "Einzel-Bild-Roentgen-Analyse"(EBRA-FCA, femoral component analysis) over a 2-year follow-up. The incidence of stress-shielding and cortical hypertrophy as well as clinical outcome [Harris Hip Score (HHS)] were reported.


RESULTS
Postoperative CCD angles ranged from 117.9° to 145.6° and mean postoperative CCD angles in group A-E were 123.3°, 128.0°, 132.4°, 137.5°, and 142.5°, respectively. After 2 years, the mean varus/valgus tilt was -0.16°, 0.37°, 0.48°, 0.01°, and 0.86°, respectively (p = 0.502). Axial subsidence after 2 years was 1.20, 1.02, 1.44, 1.50, and 2.62 mm, respectively (p = 0.043). No periprosthetic fractures occurred and none of the stems had to be revised. Rates of stress-shielding and cortical hypertrophy as well as HHS showed no significant difference between the groups.


CONCLUSIONS
Valgus alignment results in increased subsidence but does not affect the clinical outcome. There is no difference in stress shielding and cortical hypertrophy between the groups. The authors recommend long term monitoring of valgus aligned stems.
Department of Orthopaedic Surgery and Traumatology, St. Josefs Hospital Wiesbaden, Beethovenstr. 20, 65189, Wiesbaden, Germany. kkutzner@joho.de.
Karl Philipp
KP
Kutzner
Department of Orthopaedic Surgery, University of Ulm, Oberer Eselsberg 45, 89081, Ulm, Germany.
Tobias
T
Freitag
Department of Orthopaedic Surgery and Traumatology, St. Josefs Hospital Wiesbaden, Beethovenstr. 20, 65189, Wiesbaden, Germany.
Stefanie
S
Donner
Department of Traumatology, Hand- and Orthopaedic Surgery, HELIOS Dr. Horst Schmidt Clinic Wiesbaden, Ludwig-Erhard-Str. 100, 65199, Wiesbaden, Germany.
Mark Predrag
MP
Kovacevic
Department of Orthopaedic Surgery, University of Ulm, Oberer Eselsberg 45, 89081, Ulm, Germany.
Ralf
R
Bieger
D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D060906:Coxa Valga / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000503:physiopathology; D060905:Coxa Vara / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000503:physiopathology; D005260:Female; D005271:Femur Head Necrosis / Q000601:surgery; D006615:Hip / Q000601:surgery; D006618:Hip Dislocation, Congenital / Q000601:surgery; D006621:Hip Joint / Q000601:surgery; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000601:surgery; D015207:Osteoarthritis, Hip / Q000601:surgery*; D057068:Periprosthetic Fractures / Q000453:epidemiology; D011183:Postoperative Complications / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000503:physiopathology; D011184:Postoperative Period; D011474:Prosthesis Design; D011859:Radiography; D000072177:Radiologists; D012189:Retrospective Studies; D016896:Treatment Outcome
Cortical hypertrophy; EBRA; Optimys; Short stem; Stem alignment; Stress-shielding; Total hip arthroplasty; Valgus; Varus