Total hip arthroplasty using a short-stem prosthesis: restoration of hip anatomy.
OBJECTIVE
To evaluate hip parameters such as vertical centre of rotation (VCR), horizontal centre of rotation (HCR), femoral offset, and leg length after total hip arthroplasty (THA) using the Nanos short-stem prosthesis.


METHODS
Medical records of 73 men and 74 women aged 25 to 92 (mean, 63) years who underwent THA using the Nanos short-stem prosthesis by a single surgeon were reviewed. Prior to the surgery, the optimal cup and stem size, head length, and level of the neck osteotomy were determined using radiographs. Intra-operatively, the leg length and femoral offset were checked, and the level of neck resection and head length were adjusted. VCR, HCR, femoral offset, and leg length of the operated and contralateral sides were compared. Functional outcomes were assessed using the Harris Hip Score (HHS).


RESULTS
Compared with the normal contralateral hips, the operated hips had a mean increase of 0.4 mm in VCR (p=0.032), a mean decrease of 1.4 mm in HCR (p=0.027), a mean increase of 0.6 mm in femoral offset (p=0.043), and a mean increase of 0.36 mm in leg length (p=0.035). For these respective parameters, the difference between the normal contralateral side and the operated side was within 5 mm in 89%, 80%, 71%, and 96% of patients. The HHS improved from a mean of 53 to 91 at one year (p<0.001).


CONCLUSIONS
THA using the Nanos short-stem prosthesis enabled restoration of hip anatomy (VCR, HCR, femoral offset, and leg length).
Malabar Orthopaedic Institute, The Avenue Hospital, Melbourne, Australia & Instituto Traumatológico de Santiago, Santiago, Chile.
Tomas
T
Amenabar
Malabar Orthopaedic Institute, The Avenue Hospital, Melbourne, Australia.
Kanniraj
K
Marimuthu
Malabar Orthopaedic Institute, The Avenue Hospital, Melbourne, Australia.
Gabrielle
G
Hawdon
Malabar Orthopaedic Institute, The Avenue Hospital, Melbourne, Australia.
Alessandro
A
Gildone
Malabar Orthopaedic Institute, The Avenue Hospital, Melbourne, Australia.
Stephen
S
McMahon
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip; D005260:Female; D005269:Femur / Q000033:anatomy & histology / Q000601:surgery; D006621:Hip Joint / Q000033:anatomy & histology / Q000601:surgery*; D006622:Hip Prosthesis; D006801:Humans; D007592:Joint Diseases / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D012399:Rotation
arthroplasty, replacement, hip; hip prosthesis; leg length inequality