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Distal femoral stem-bone anchorage of a cementless revision total hip arthroplasty: evaluation of 14 patients by CT.

Weiss RJ, Strömwall F, Beckman MO, Hansson KA, Stark A - Acta Orthop (2009)

Bottom Line: Still, at the 1-year control, all patients were fully weight-bearing and only 1/14 complained about mild thigh pain. 7/14 patients did not experience any pain in the affected hip.The clinical outcome at 5 years was unchanged.However, this does not appear to be necessary to obtain stability and to achieve clinically satisfying results.

View Article: PubMed Central - PubMed

Affiliation: Section of Orthopaedics and Sports Medicine, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden. rudiger.weiss@karolinska.se

ABSTRACT

Background and purpose: According to the manual of the cementless Link MP reconstruction prosthesis, a distal femoral stem-bone anchorage of at least 80 mm is necessary to gain implant stability. There have been no in vivo studies showing that this distance is either achieved in clinical practice or needed for clinically satisfying results. Thus, we assessed the femoral stem-bone anchorage of the MP prosthesis using CT.

Methods: 14 patients with the MP stem were evaluated by CT scans at a median follow-up time of 12 months postoperatively. Femoral stem-bone anchorage was defined as adequate if 50% of the stem flutes or more had cortical bone contact. The length of anchorage was derived from the number of slices with adequate anchorage. Clinical outcome was assessed with VAS for pain and Harris hip score (HHS), both at 1 and 5 years of follow-up.

Results: The median length of stem-bone anchorage was 33 mm (interquartile range 10-60), which was shorter than recommended (p = 0.002). Still, at the 1-year control, all patients were fully weight-bearing and only 1/14 complained about mild thigh pain. 7/14 patients did not experience any pain in the affected hip. The patients had a median of 85 points in the HHS. The clinical outcome at 5 years was unchanged.

Interpretation: We found that it can be difficult to achieve a stem-bone anchorage of at least 80 mm for the MP Link prosthesis. However, this does not appear to be necessary to obtain stability and to achieve clinically satisfying results.

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Related in: MedlinePlus

Computer-assisted tomography showing transverse planes of different levels of a patient's femur with a cementless Link MP reconstruction prosthesis. The stem contains 8 longitudinal distal flutes to provide rotational stability. More (A) and less (B) than 50% of the flutes have cortical bone contact.
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Figure 0002: Computer-assisted tomography showing transverse planes of different levels of a patient's femur with a cementless Link MP reconstruction prosthesis. The stem contains 8 longitudinal distal flutes to provide rotational stability. More (A) and less (B) than 50% of the flutes have cortical bone contact.

Mentions: CT scans were performed with a protocol using Picker PQ 5000 single-slice (Picker International, Cleveland, OH) or GE lightspeed 16-slice (GE Healthcare) CT machines according to availability. The single-slice protocol used 120 kV, 175 mA, pitch 2, and rotation of 1 second. The 16-slice protocol used 120 kV, pitch 1.375, a rotation time of 0.6 second and a noise index of 15, yielding approximately the same radiation dose for the patients and equivalent picture quality. Pictures were reconstructed with a 5-mm interval without overlap (Figure 2A and B). All CT scans were analyzed separately by 2 blinded radiologists. Intraclass correlation coefficient was used to measure inter-rater reliability.


Distal femoral stem-bone anchorage of a cementless revision total hip arthroplasty: evaluation of 14 patients by CT.

Weiss RJ, Strömwall F, Beckman MO, Hansson KA, Stark A - Acta Orthop (2009)

Computer-assisted tomography showing transverse planes of different levels of a patient's femur with a cementless Link MP reconstruction prosthesis. The stem contains 8 longitudinal distal flutes to provide rotational stability. More (A) and less (B) than 50% of the flutes have cortical bone contact.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2823214&req=5

Figure 0002: Computer-assisted tomography showing transverse planes of different levels of a patient's femur with a cementless Link MP reconstruction prosthesis. The stem contains 8 longitudinal distal flutes to provide rotational stability. More (A) and less (B) than 50% of the flutes have cortical bone contact.
Mentions: CT scans were performed with a protocol using Picker PQ 5000 single-slice (Picker International, Cleveland, OH) or GE lightspeed 16-slice (GE Healthcare) CT machines according to availability. The single-slice protocol used 120 kV, 175 mA, pitch 2, and rotation of 1 second. The 16-slice protocol used 120 kV, pitch 1.375, a rotation time of 0.6 second and a noise index of 15, yielding approximately the same radiation dose for the patients and equivalent picture quality. Pictures were reconstructed with a 5-mm interval without overlap (Figure 2A and B). All CT scans were analyzed separately by 2 blinded radiologists. Intraclass correlation coefficient was used to measure inter-rater reliability.

Bottom Line: Still, at the 1-year control, all patients were fully weight-bearing and only 1/14 complained about mild thigh pain. 7/14 patients did not experience any pain in the affected hip.The clinical outcome at 5 years was unchanged.However, this does not appear to be necessary to obtain stability and to achieve clinically satisfying results.

View Article: PubMed Central - PubMed

Affiliation: Section of Orthopaedics and Sports Medicine, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden. rudiger.weiss@karolinska.se

ABSTRACT

Background and purpose: According to the manual of the cementless Link MP reconstruction prosthesis, a distal femoral stem-bone anchorage of at least 80 mm is necessary to gain implant stability. There have been no in vivo studies showing that this distance is either achieved in clinical practice or needed for clinically satisfying results. Thus, we assessed the femoral stem-bone anchorage of the MP prosthesis using CT.

Methods: 14 patients with the MP stem were evaluated by CT scans at a median follow-up time of 12 months postoperatively. Femoral stem-bone anchorage was defined as adequate if 50% of the stem flutes or more had cortical bone contact. The length of anchorage was derived from the number of slices with adequate anchorage. Clinical outcome was assessed with VAS for pain and Harris hip score (HHS), both at 1 and 5 years of follow-up.

Results: The median length of stem-bone anchorage was 33 mm (interquartile range 10-60), which was shorter than recommended (p = 0.002). Still, at the 1-year control, all patients were fully weight-bearing and only 1/14 complained about mild thigh pain. 7/14 patients did not experience any pain in the affected hip. The patients had a median of 85 points in the HHS. The clinical outcome at 5 years was unchanged.

Interpretation: We found that it can be difficult to achieve a stem-bone anchorage of at least 80 mm for the MP Link prosthesis. However, this does not appear to be necessary to obtain stability and to achieve clinically satisfying results.

Show MeSH
Related in: MedlinePlus