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Periprosthetic DXA after total hip arthroplasty with short vs. ultra-short custom-made femoral stems: 37 patients followed for 3 years.

Albanese CV, Santori FS, Pavan L, Learmonth ID, Passariello R - Acta Orthop (2009)

Bottom Line: We found that progressive shortening of the femoral stem produces more proximal loading, which effectively preserves metaphyseal bone stock and increases periprosthetic BMD in the medial ROIs over time.In the type 2 group, higher absolute BMD values were observed in medial ROIs 4 and 5.No differences were found in ROIs 1, 2, and 3.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiological Science, Sapienza University, Rome. carlina.albanese@uniroma1.it

ABSTRACT

Background and purpose: Dual-energy X-ray absorptiometry (DXA) analysis of the 7 periprosthetic Gruen zones is the most commonly used protocol to evaluate bone remodeling after the implantation of conventional femoral stems. We assessed the value of DXA after cementless primary total hip arthroplasty (THA) by comparing the effect of progressive shortening of the stem of two femoral implants on periprosthetic bone remodeling using a specifically developed protocol of analysis with 5 periprosthetic regions of interest (ROIs).

Patients and methods: Bone mineral density (BMD) was evaluated in 37 patients in the plateau stage, 3 years after THA. Two femoral implants featuring conceptually new designs and surgical technique were tested: types 1 and 2, characterized by extremely short stem and virtual absence of distal stem, respectively.

Results: We found that progressive shortening of the femoral stem produces more proximal loading, which effectively preserves metaphyseal bone stock and increases periprosthetic BMD in the medial ROIs over time. In the type 2 group, higher absolute BMD values were observed in medial ROIs 4 and 5. No differences were found in ROIs 1, 2, and 3.

Interpretation: This study shows the flexibility of DXA in adapting the protocol of periprosthetic analysis to the specific requirements of new implant designs, and it shows its high sensitivity in evaluation of the biological response of bone to changes in implant shape.

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Related in: MedlinePlus

Type 1 custom-made femoral implant featuring an extremely short distal stem. DXA images of the proximal femoral periprosthetic analysis with 5 regions of interest (R1–R5).
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Figure 0001: Type 1 custom-made femoral implant featuring an extremely short distal stem. DXA images of the proximal femoral periprosthetic analysis with 5 regions of interest (R1–R5).

Mentions: Two slightly different new anatomical models of design were tested: the first model (type 1; Stanmore Orthopaedics, Stanmore, UK) was fully coated and featured an extremely short distal stem, which never extended more than 3 cm below the lesser trochanter (n = 16). The tip of the second model (type 2; DePuy International Ltd., Leeds, UK) never extended below the lesser trochanter (n = 21). Both models were cementless and had a large lateral flare (Figures 1 and 2). Preoperatively, each patient underwent a CT examination of the affected hip and a custom-made implant was specifically manufactured for each patient. The same surgeon (FSS) performed all operations in both study groups using the operative technique previously described by Santori et al. (2006c). At the time of the operation, the surgeon was provided with a single customized implant and a single corresponding broach. Standard radiographs were taken of all patients at the time of surgery and, postoperatively, at 1, 6, and 12 months, and annually thereafter as previously described (Santori et al. 2006a). The occurrence of stem subsidence and the appearance of radiolucent lines were recorded. A deviation greater than 2° from the longitudinal femoral axis was rated as either a varus or a valgus malpositioning. Clinical assessments were done using the Harris hip score. Periarticular calcifications were rated according to Brooker et al. (1973). All patients underwent partial weight bearing for 6 weeks and had a 3-month postoperative rehabilitation supervised by a physiotherapist. The height (cm) and weight (kg) of patients were measured.


Periprosthetic DXA after total hip arthroplasty with short vs. ultra-short custom-made femoral stems: 37 patients followed for 3 years.

Albanese CV, Santori FS, Pavan L, Learmonth ID, Passariello R - Acta Orthop (2009)

Type 1 custom-made femoral implant featuring an extremely short distal stem. DXA images of the proximal femoral periprosthetic analysis with 5 regions of interest (R1–R5).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2823205&req=5

Figure 0001: Type 1 custom-made femoral implant featuring an extremely short distal stem. DXA images of the proximal femoral periprosthetic analysis with 5 regions of interest (R1–R5).
Mentions: Two slightly different new anatomical models of design were tested: the first model (type 1; Stanmore Orthopaedics, Stanmore, UK) was fully coated and featured an extremely short distal stem, which never extended more than 3 cm below the lesser trochanter (n = 16). The tip of the second model (type 2; DePuy International Ltd., Leeds, UK) never extended below the lesser trochanter (n = 21). Both models were cementless and had a large lateral flare (Figures 1 and 2). Preoperatively, each patient underwent a CT examination of the affected hip and a custom-made implant was specifically manufactured for each patient. The same surgeon (FSS) performed all operations in both study groups using the operative technique previously described by Santori et al. (2006c). At the time of the operation, the surgeon was provided with a single customized implant and a single corresponding broach. Standard radiographs were taken of all patients at the time of surgery and, postoperatively, at 1, 6, and 12 months, and annually thereafter as previously described (Santori et al. 2006a). The occurrence of stem subsidence and the appearance of radiolucent lines were recorded. A deviation greater than 2° from the longitudinal femoral axis was rated as either a varus or a valgus malpositioning. Clinical assessments were done using the Harris hip score. Periarticular calcifications were rated according to Brooker et al. (1973). All patients underwent partial weight bearing for 6 weeks and had a 3-month postoperative rehabilitation supervised by a physiotherapist. The height (cm) and weight (kg) of patients were measured.

Bottom Line: We found that progressive shortening of the femoral stem produces more proximal loading, which effectively preserves metaphyseal bone stock and increases periprosthetic BMD in the medial ROIs over time.In the type 2 group, higher absolute BMD values were observed in medial ROIs 4 and 5.No differences were found in ROIs 1, 2, and 3.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiological Science, Sapienza University, Rome. carlina.albanese@uniroma1.it

ABSTRACT

Background and purpose: Dual-energy X-ray absorptiometry (DXA) analysis of the 7 periprosthetic Gruen zones is the most commonly used protocol to evaluate bone remodeling after the implantation of conventional femoral stems. We assessed the value of DXA after cementless primary total hip arthroplasty (THA) by comparing the effect of progressive shortening of the stem of two femoral implants on periprosthetic bone remodeling using a specifically developed protocol of analysis with 5 periprosthetic regions of interest (ROIs).

Patients and methods: Bone mineral density (BMD) was evaluated in 37 patients in the plateau stage, 3 years after THA. Two femoral implants featuring conceptually new designs and surgical technique were tested: types 1 and 2, characterized by extremely short stem and virtual absence of distal stem, respectively.

Results: We found that progressive shortening of the femoral stem produces more proximal loading, which effectively preserves metaphyseal bone stock and increases periprosthetic BMD in the medial ROIs over time. In the type 2 group, higher absolute BMD values were observed in medial ROIs 4 and 5. No differences were found in ROIs 1, 2, and 3.

Interpretation: This study shows the flexibility of DXA in adapting the protocol of periprosthetic analysis to the specific requirements of new implant designs, and it shows its high sensitivity in evaluation of the biological response of bone to changes in implant shape.

Show MeSH
Related in: MedlinePlus