Femoral cement pressurization in hip arthroplasty: a comparison of 3 systems

Cementation technique for elbow arthroplasty; an international survey

Background

Modern cementation techniques have markedly improved survivorship in lower limb arthroplasty, which have been heavily researched in the hip and knee but less so for upper limb procedures. Aseptic loosening is a leading cause of failure in total elbow arthroplasty (TEA) which could be related to the quality of cementation. The aim of this study was to investigate the cementation techniques used for TEA among practicing elbow surgeons.

Methods

An electronic questionnaire was emailed to members of the British elbow and shoulder society (BESS) and PubMed identified experts. Questions focused on the type of prosthesis, operative rates for elective and trauma cases, nature of cement used, canal preparation and cement insertion. Opinions regarding satisfaction with current techniques and mantle quality were also collected.

Results

A total of 26 surgeons completed the questionnaire. The Coonrad-Moorey was the most popular device amongst respondents. Most cemented both components, used antibiotic loaded cement, washed the canal with saline and inserted the cement retrograde. There was wide variation in cementation techniques used for the humerus and ulna, particularly regarding cement preparation, insertion, and use of a restrictor and pressurisation.

Conclusion

Modern cementation techniques are not being utilised in TEA which could be contributing to implant loosening rates and longevity.

Comparison of two pressurisers for cementation of the proximal femur

PURPOSE

To compare pressures generated by 2 different cement pressurisers at various locations in the proximal femur.

METHODS

Two groups of 5 synthetic femurs were used, and 6 pressure sensors were placed in the femur at 20-mm intervals proximally to distally. Cement was filled into the femoral canal retrogradely using a cement gun with either the half-moon pressuriser or the femoral canal pressuriser. Maximum pressures and pressure time integrals (cumulative pressure over time) of the 2 pressurisers were compared.

RESULTS

At all sensors, the half-moon pressuriser produced higher maximum pressures and pressure time integrals than the femoral canal pressuriser, but the difference was significant only at sensor 1 (proximal femur). This may result in reduced cement interdigitation in the proximal femur.

CONCLUSION

The half-moon pressuriser produced higher maximum cementation pressures and pressure time integrals than the femoral canal pressuriser in the proximal femur region, which is critical for rotational stability of the implant and prevention of implant fracture.

Better primary stability with porous titanium particles than with bone particles in cemented impaction grafting: an in vitro study in synthetic acetabula

AIMS

Impaction bone grafting creates new bone stock after hip joint replacement. Utilizing a synthetic bone substitute instead of bone might increase primary stability and is not associated with graft shortage and pathogen transmission. This study compares the initial stability of a graft layer of porous titanium particles (TiP), cancellous bone particles, and a 1:2 bone-titanium mix in synthetic cemented acetabular reconstructions. Displacement was measured by radiostereometric analysis after cyclic loading (1 Hz, maximum stress 2.5 MPa). Shear stress resistance was quantified by a lever out test of the cup. Cement penetration was quantified from cross-sections.

FINDINGS

Titanium reconstructions showed less residual displacement (0.13 ± 0.13 mm) than pure bone particle reconstructions (0.57 ± 0.18 mm) (p < 0.01). Titanium reconstructions were also more resistant to shear stress (p < 0.001). The bone-titanium mix showed intermediate results. Cement penetrated deeper into the bone particle graft layers (4.8 ± 0.7) than into the titanium graft layers (3.8 ± 0.5 mm) (p < 0.02).

CONCLUSIONS

Cemented acetabular revision reconstructions with porous TiP show better initial stability despite less cement penetration than bone particle reconstructions. Realistic preclinical in vivo testing should explore the hypothesis that porous TiP offer a safe alternative to the current gold standard of bone grafts.

A novel technique for femoral canal occlusion during cement pressurization in proximal femoral arthroplasty

We describe a novel technique for occluding the femoral canal distal to the isthmus during proximal femoral arthroplasty. Synthetic bone models were reamed and sectioned to simulate loss of the proximal femur. Two experimental conditions were used. The first used no restrictor to act as a control. The second used calcium sulphate pellets impacted in distal femoral canal. A 100 × 12 mm Limb Preservation System stem (DePuy, Leeds, UK) was used in all experiments. We recorded cement pressure, leakage of cement, and penetration of cement into the femoral condyles. The calcium sulphate pellets prevented cement leakage, enabled higher cementing pressures, and prevented penetration of the cement into the femoral condyles. We would recommend this technique in cases where loss of proximal femoral bone loss requires the use of a cemented proximal femoral replacement.

No benefit of a proximal stem centralizer in cementing of a femoral prosthesis in human cadavers

BACKGROUND AND PURPOSE

A proximal stem centralizer may be beneficial regarding cementing pressures, cement penetration, and stem alignment. We measured these parameters when cementing a mat-surfaced femoral component with and without the use of a proximal stem centralizer.

MATERIAL AND METHODS

8 femoral prostheses with proximal centralizers and 8 femoral prostheses without proximal centralizers were cemented according to third-generation cementing technique in 8 pairs of embalmed cadaveric femora. We recorded intramedullary pressures (peak levels, the area under the pressure curves and mean pressure) with 6 pressure transducers during stem cementation. Computer tomographic scanning of specimens was performed to evaluate stem alignment after surgery. Thickness of the cement mantle, cement penetration, and stem centralization at the metaphyseal part of the femur were measured on cross sections using stereology.

RESULTS

There were no statistically significant differences in measured pressure and cement penetration values between the groups. There was similar cement distribution around the stems; however, in using a proximal centralizer, the cement mantle tended to be thinner laterally. Moreover, we found a larger variation in stem alignment on lateral projection in the proximal centralizer group.

INTERPRETATION

No benefits regarding intramedullary pressures and cement penetration were obtained from cementation of a straight stem with a proximal stem centralizer. However, there was an increased risk of inferior stem positioning in the reamed medullary cavity using the centralizing device.

Osteogenic activity of locally applied small molecule drugs in a rat femur defect model

The long-term success of arthroplastic joints is dependent on the stabilization of the implant within the skeletal site. Movement of the arthroplastic implant within the bone can stimulate osteolysis, and therefore methods which promote rigid fixation or bone growth are expected to enhance implant stability and the long-term success of joint arthroplasty. In the present study, we used a simple bilateral bone defect model to analyze the osteogenic activity of three small-molecule drug implants via microcomputerized tomography (micro-CT) and histomorphometry. In this study, we show that local delivery of alendronate, but not lovastatin or omeprazole, led to significant new bone formation at the defect site. Since alendronate impedes osteoclast-development, it is theorized that alendronate treatment results in a net increase in bone formation by preventing osteoclast mediated remodeling of the newly formed bone and upregulating osteoblasts.

Comparison of two methods of fatigue testing bone cement

Two different methods have been used to fatigue test four bone cements. Each method has been used previously, but the results have not been compared. The ISO 527-based method tests a minimum of 10 samples over a single stress range in tension only and uses Weibull analysis to calculate the median number of cycles to failure and the Weibull modulus. The ASTM F2118 test regime uses fewer specimens at various stress levels tested in fully reversed tension-compression, and generates a stress vs. number of cycles to failure (S-N) or Wöhler curve. Data from specimens with pores greater than 1mm across is rejected. The ISO 527-based test while quicker to perform, provides only tensile fatigue data, but the material tested includes pores, thus the cement is closer to cement in clinical application. The ASTM regime uses tension and compression loading and multiple stress levels, thus is closer to physiological loading, but excludes specimens with defects obviously greater than 1mm, so is less representative of cement in vivo. The fatigue lives between the cements were up to a factor 15 different for the single stress level tension only tests, while they were only a factor of 2 different in the fully reversed tension-compression testing. The ISO 527-based results are more sensitive to surface flaws, thus the differences found using ASTM F2118 are more indicative of differences in the fatigue lives. However, ISO 527-based tests are quicker, so are useful for initial screening.