Bone mineral density changes of the proximal tibia after revision total knee arthroplasty. A randomised study with the use of porous tantalum metaphyseal cones.
OBJECTIVE
Forty patients were enrolled in a prospective randomised study using conventional method or "Trabecular Metal Cone" (TM Cone) (Zimmer inc., Warsaw, USA) for reconstruction of bone loss of the proximal tibia during revision total knee arthroplasty (rTKA). The aim was to evaluate changes in bone mineral density (BMD) at the proximal tibia.


METHODS
Thirty-six patients [median 67 years (range: 40-85 years)] received rTKA with NexGen® (Zimmer Warsaw, USA) revision system. Knee Society´s Knee Scoring System and the Anderson Orthopaedic Research Institute (AORI) bone classification was used. Changes in BMD were measured by dual energy X-ray absorptiometry (DEXA).


RESULTS
Knee and function score improved in both groups. No significant changes between the groups were found. Changes in BMD within the two groups were quite similar. Overall decreases in BMD of 0.1 - 5.4 % were found in both groups (ROI 1-6) postoperative to 12 months of follow-up, except that ROI 7 showed an increase in BMD (0.8 - 1.3 %). After 24 months of follow-up, an increase in BMD was found along the stem (ROI 2-5) of 1.9 - 6.3 % , with significant changes in the TM Cone Group (ROI 3, 4, 5) . No significant changes in BMD between the groups were found.


CONCLUSIONS
The bone remodelling pattern was almost the same in the two groups after two years.
Department of Orthopaedic Surgery U, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, 2100 Copenhagen Ø, Denmark. clindkaer@gmail.com
Claus L
CL
Jensen
Michael M
MM
Petersen
Henrik M
HM
Schrøder
Bjarne
B
Lund
D015502:Absorptiometry, Photon; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects; D015519:Bone Density; D016723:Bone Remodeling / Q000502:physiology; D001862:Bone Resorption / Q000175:diagnosis* / Q000209:etiology / Q000601:surgery; D018786:Bone Substitutes; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology / Q000601:surgery; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D016348:Osseointegration; D011183:Postoperative Complications / Q000209:etiology; D011446:Prospective Studies; D011474:Prosthesis Design; D020127:Recovery of Function; D012086:Reoperation; D013635:Tantalum; D013977:Tibia / Q000000981:diagnostic imaging / Q000378:metabolism*; D016896:Treatment Outcome
D018786:Bone Substitutes; D013635:Tantalum