Radiographic alterations in short-stem total hip arthroplasty: a 2-year follow-up study of 216 cases.
BACKGROUND
In recent years a variety of short-stems have been introduced. Stable osteointegration is a key factor for a satisfactory long-term result. The purpose of this study was to evaluate postoperative radiological alterations and subsidence, as a result of using a newly developed device, over a 2-year follow-up.


METHODS
216 short-stems were implanted in combination with a cementless cup. Patients were allowed full weight-bearing on the first day postoperatively. Pre- and postoperative x-rays were done using a standardised technique. Radiological alterations, such as bone resorption, radiolucency, osteolysis and cortical hypertrophy were detected and located using modified Gruen zones, and subsidence was measured via a conventional digital technique over a 2-year follow-up. In addition, Harris Hip Score (HHS), rest pain and load pain on the visual analogue scale (VAS) were assessed respectively.


RESULTS
At 2-year follow-up 6 stems (2.9%) showed nonprogressive radiolucent lines with a maximum width of 2 mm. Resorption of femoral bone stock was detected in a total of 8 cases (3.9%). Femoral cortical hypertrophy was seen in a total of 9 hips (4.4%). No patient showed osteolysis. A measureable subsidence of at least 2 mm was observed in a total of 15.7% (32 cases) after 6 weeks, corresponding to an initial settlement given full weight-bearing ambulation. Only 1.1% (2 cases) showed further progression at the 6-month follow-up, whereas at the 1- and 2-year follow-ups no further subsidence was observed. After 2 years HHS was 98.1 (65.0-100.0), rest pain on the VAS was 0.2 (0.0-7.0) while load pain was 0.4 (0.0-7.0).


CONCLUSIONS
The results of this radiographic analysis give support to the principle of using metaphyseal anchoring, calcar guided short-stems. The low incidence of bony alterations after a follow-up of 2 years indicates a physiological load distribution. After mild initial subsidence a stable osteointegration can be achieved over time.
Clinic for Orthopaedic Surgery and Traumatology, St. Josefs Hospital Wiesbaden, Wiesbaden - Germany.
Karl P
KP
Kutzner
Clinic for Orthopaedic Surgery and Traumatology, St. Josefs Hospital Wiesbaden, Wiesbaden - Germany.
Dominik
D
Pfeil
Clinic for Traumatology, Hand and Orthopaedic Surgery, Dr. Horst Schmidt Clinic Wiesbaden, Wiesbaden - Germany.
Mark P
MP
Kovacevic
Clinic for Orthopaedic Surgery and Traumatology, St. Josefs Hospital Wiesbaden, Wiesbaden - Germany.
Philipp
P
Rehbein
Vitos Clinic for Orthopaedics Kassel, Kassel - Germany.
Sabine
S
Mai
Vitos Clinic for Orthopaedics Kassel, Kassel - Germany.
Werner
W
Siebert
Clinic for Orthopaedic Surgery and Traumatology, St. Josefs Hospital Wiesbaden, Wiesbaden - Germany.
Joachim
J
Pfeil
D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000379:methods*; D016723:Bone Remodeling / Q000502:physiology; D001862:Bone Resorption / Q000000981:diagnostic imaging* / Q000503:physiopathology; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods; D010147:Pain Measurement; D011182:Postoperative Care; D011446:Prospective Studies; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011859:Radiography / Q000379:methods*; D018709:Statistics, Nonparametric; D013997:Time Factors; D016896:Treatment Outcome