Introduction

Cemented Total Hip Arthroplasty (THA) is an extremely successful procedure with unsurpassed success. Recent data from multiple national joint registries show that cemented stems have superior long-term survival across all patient groups; long-term survival rates above 90 to 95% for 10 plus years can be expected.1-5 These results can only be achieved with good operative techniques. The stepwise process of modern cementation allows for an optimal interlock between the implant and bone. Each step has a distinct purpose and has been developed to address a specific issue to enhance the probability of success. Proper cement interdigitation is dependent on the entire process from the bone preparation to the method of lavage and the technique of cement application and pressurization. The chance of revision can be decreased by 20% for each properly executed step.6,7 Particularly crucial is the use of pulsatile lavage, not only crucial for obtaining an optimal cement mantle, but also to decrease the risk of fat embolism.8-10 Proper lavage is considered as a mandatory step in cemented THA.

The authors preferred operative technique for the insertion of a cemented femoral prostheses is outlined in a stepwise fashion.

Surgical Technique

Hypotensive anesthesia with the use of a spinal or epidural injection is preferred, if safe for the patient. This allows for a low systolic blood pressure (<80-90 mm Hg) to be maintained at the time of cementation, which is essential to decrease bleeding at the cement bone interface and obtain an optimal cement mantle. Regional anesthesia has also been shown to decrease the incidence of venous thrombosis and decrease the incidence of postoperative mental status changes.11-14 An anesthetist with experience and interest in arthroplasty contributes to the ease and success of the procedure.

The surgical approach to the hip is performed. The author routinely uses a posterolateral approach with repair of the posterior capsule and external rotators but any approach can be used provided that the exposure allows for an unobstructed view of the proximal femur without soft tissue impingement on the instruments. Minimally invasive techniques are also possible if adequate exposure is accomplished.

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Operative Steps

PREPARATION OF THE FEMUR

Identification of the Pyriformis Fossa

Total Hip Arthroplasty

Barring abnormal bone structure, the femoral canal is in line with the pyriformis fossa.15 The pyriformis fossa is identified and cleared of any remaining soft tissue. The entry point will be posterolateral directly in line with the femoral canal (Fig. 12.1). This will allow for reaming in the appropriate direction. This prevents varus positioning of the femoral component and reduces the risk of a thin cement mantel in Gruen zones 8/9.16-18

Femoral Head and Neck Resection

The femoral neck is cut at the preoperatively template level. This resection is generally

1.5 to 2.0 cm above the level of the proximal aspect of the junction of the lesser trochanter with the femoral neck. The exact level of resection is only crucial if a collared implant is to be used. Additionally, if a collared stem is used, the level of the neck cut grossly determines leg length; final adjustment of the resection level may be needed later after implants are trialed for leg length and stability. A higher neck cut at 35o to the femoral shaft axis can be beneficial as the preservation of the distal femoral neck increases rotational stability of the stem.19,20 Osteotomy is accomplished with an oscillating saw, an osteotome, or a combination of the two. Care is taken to protect the surrounding soft tissues and the greater trochanter.

Canal Entry

The remaining bone in the pyriformis fossa is removed with an initial trocar awl, rongeur, or osteotome. The canal is then entered with an initial trocar awl in line with the axis of the femoral shaft.

Entry to the femoral shaft via the neck will invariably result in malpositioned implants (Fig. 12.2). This is due to the anteversion of the femoral neck; instruments will be aimed incorrectly and impact the femoral cortex. This could result in a cortical breech if not noticed and care must be taken to avoid this mistake.

Figure 12.1: The entry point is posterolateral directly in line with femoral canal

Figure 12.2: If the direction of canal entry follows the femoral neck axis (Yellow Line) instead of the femoral shaft axis (Dashed Red Line) implant malposition, a thin cement mantle and/or a cortical breech will occur

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Figure 12.3: Initial reaming must be started posterior and follow the orientation of the femoral shaft axis. The images demonstrate the correct position of the entry point, posterior on the femur

Cementing Technique: Femur

Opening the Medullary Canal

The canal is entered with a blunt tipped T-handled canal finder. The blunt tip minimizes the risk of femoral cortex perforation, preserves distal cancellous bone and prevents disruption to the arterial blood supply.21 The canal finder is gently rotated as it is inserted and contact with the posterior calcar region is maintained to ensure correct alignment (Fig. 12.3).

Insertion and advancement of the canal finder should be easy and the tip should not impact the cortex when aligned appropriately. Correct positioning is indicated with preservation of cancellous bone anteriorly as well as a posteriorly positioned canal finder. Proper entry into the intramedullary canal is of crucial importance as the remainder of the operative steps build on this position. The most common reason for error is due to soft tissue impingement misdirecting the instruments either anteriorly if a posterior approach or posteriorly with an anterior approach.

Preparation of the Proximal Femur

Once the proper axis of the femoral canal is determined with the canal finder, it is necessary to open the lateral portion of the femoral neck with a box osteotome. If broaching is begun without this step, the proximal cancellous bone would become compacted, destroying the interstices needed for proper cement interdigitation. The box osteotome is placed at the lateral edge of the femoral shaft axis and directed parallel to the calcar to remove a wedge of cancellous bone. 3 to 5 mm of cancellous bone should be left medially along the calcar to enhance later cement interdigitation.22 A varus trochanter or an implant with a prominent lateral shoulder requires a significant amount of bone to be removed laterally (Fig. 12.4). A good intraoperative indicator of appropriate laterality is the presence of cancellous bone on the medial aspect of the trochanter at the junction with the pyriformis fossa.

When removing the box osteotome, it is crucial not to lever on the trochanter as it is easy to fracture if this is attempted. All forces should be kept inline or directed medially. It is important not to leave a cortical rim which could cause the broach to be misguided. The use of an osteotome or rongeur is sometimes needed if further lateral positioning is required.

Sequential reaming is now carried out if dictated by the specific implant system. If not needed, then proceed directly to femoral broaching.

Broaching

Sequential broaching of the femur is done while carefully monitoring the fill of the proximal femur. The goal with broaching is to preserve 3 mm of medial and anterior cancellous bone

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Total Hip Arthroplasty

Figure 12.4: A varus trochanter or an implant with a prominent lateral shoulder may require removal of more lateral bone. Take care not to lever on the trochanter with the osteotome. Ensure that no remaining cortical remnant exists at the entry point to misdirect instruments during canal preparation

(Fig. 12.5). This will ensure an appropriate cement mantle with good proximal interdigitation. Lateral and posterior pressure is maintained on the broach handle to assist in maintaining the proximal cancellous bone and guide the broach into good position. Mallet strikes onto the medial edge of the inserter handle help to force the broach laterally to optimize position. Preoperative templating is used to help to determine stem size. It is important to refrain from inserting the largest broach size possible. This technique of broaching is a departure from the techniques used with many cementless stems where cortical purchase is obtained. Cementless surgeons need to be cognizant of this difference. Preservation of a rim of strong cancellous bone is of significant importance for cemented stems. If the cancellous bone

becomes sparse downsizing of the stem is recommended.

Figure 12.5: Broaching should be carried out using the posterior lateral entry point found earlier. Sequential broaching should cease once 3 mm of anterior and medial cancellous bone remains. This is a departure from the broaching technique used for many cementless implants

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Cementing Technique: Femur

Figure 12.6: The cement restrictor is sized and placed distal to the stem tip 1.5-2.0 cm. This should be done prior to pulsatile lavage of the femur. The femur is irrigated until the solution remains clear and then the canal is packed to prevent back bleeding

A minimum of 2 mm circumferentially around the stem is needed for a cement mantle.19,23-31 Some systems require over-broaching by at least one size; some have this 2 mm mantle included with each labeled broach size. Obtaining this mantle requires an intimate knowledge of the implant system in use.

The femoral broach is now used to trial the THA and ensure adequate stability and correct leg length is restored. Once this is established, recheck the amount of cancellous bone remaining and downsize the stem if less than 3 mm remains as discussed above.

Final Preparation of the Femoral Canal

The femoral canal is irrigated with a minimum of 1 liter of irrigation with a long nozzle tipped pulsatile lavage. This step should be done prior to sizing for the cement restrictor to lessen the chance of a fat embolism. Olive tipped sizing probes are sequentially inserted to determine the size of the cement restrictor. Generally, the cement restrictor is 2 mm larger than the size of the largest olive tipped probe. The cement restrictor should be placed 1.5-2 cm distal to the tip of the femoral stem to allow for an appropriate cement mantle distally (Fig. 12.6).

The femoral canal is then reirrigated with the same technique as above until the irrigant remains clear and the bone is white (Fig. 12.7). While the cement is being prepared, the canal is packed to minimize bleeding from the exposed cancellous surface. The authors' preference is to pack the canal with H2O2-soaked hemostatic ribbon gauze. The suction tip is left in the canal to evacuate the oxygen liberated from the chemical reaction and lessen any chance of an air embolism. Gelatin based cement restrictors can be dissolved by H2O2; if used their stability can be jeopardized. The anesthetist should be directed to keep the systolic pressure below 100 mm Hg if possible to help to minimize backbleeding.

CEMENT MIXING

Cement with a good track record with registry data and meta-analysis both supporting the routine use of low dose antibiotic laden cement.32-34 The particular characteristics of the cement, as well as the influence of ambient temperature and humidity on its physical properties should be familiar to the surgeon. A successful long term outcome is dependent on all of these factors.

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Total Hip Arthroplasty

The authors' preference is to use vacuum mixed cement which decreases porosity and increases strength and improves survival rates of the THA.7 For an average sized femur, a double batch of cement (80 grams) is required to ensure enough excess cement remains for pressurization. If the femur is a large "stove pipe" Dorr C femur, 3 batches (120 grams) of cement are mixed. It is important to determine the amount of cement required prior to mixing so that an adequately sized mixing bowl and cement gun are available. Most cement mixing systems have multiple sizes to account for these batch sizes.

The individual mixing the cement should be properly trained in the process and have a full understanding of the necessity of each step. Inexperienced, poorly, or untrained staff can easily produce a poor mixture which would provide a suboptimal clinical result.

CEMENT APPLICATION

One final time, the femoral canal is irrigated with the pulsatile lavage until the fluid is clear and the bone white. Manual lavage is ineffective, does not reduce the risk of fat embolism, and is inappropriate, even for this final lavage. Final timing of cement insertion is dependent on the type of implant used ambient conditions and surgeon preference. Cement too low in viscosity can leak past the cement restrictor (making pressurization impossible) or possibly intravasate. The authors' preference is to use medium viscosity cement.

A narrow vent tube is placed in the canal just above the cement restrictor to help remove trapped air and blood (Fig. 12.8). Once the cement has reached the desired viscosity, it is rapidly applied in a retrograde fashion. This is accomplished with a cement gun by placing the nozzle against the cement restrictor and rapidly but smoothly applying the cement. The authors' preferred method is to use a "one-handed" technique where one hand is used to stabilize and direct the cement gun and the other is used to extrude the cement. The cement gun should never be withdrawn from the canal; instead it should be "pushed out" by the addition of the cement. If the gun is withdrawn instead of being pushed out, blood voids and cement laminations will compromise the cement mantle.35-37

As the proximal femur is filled the surgeon's thumb is used to temporarily pressurize the cement by sealing the medial calcar area. As the gun is pushed from the canal, the thumb is used to resist the backbleeding pressure by sealing the femur while the gun is prepared for final pressurization. The vent tube is also removed at this stage.

The femoral seal is placed on the nozzle which is cut short, just past this seal, so it does not slide distally into the canal during pressurization. The seal is then placed against the proximal femur with care taken to ensure the entire canal opening is occluded. Pressurization is accomplished with slow, steady trigger pulls over the course of 2 to 3 minutes (Figs 12.9A to C). This allows time for good intrusion into the cancellous bone. It is critical not to run out

Figure 12.7: Before cementation, the femoral canal is again irrigated with a pulsatile lavage using a long nozzle which directs the spray at a right angle to thoroughly cleanse the canal. The canal is then dried. The appearance of an appropriately prepared femur is shown

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Cementing Technique: Femur

Figure 12.8: The vent tube is placed in the canal just before cementation to allow any trapped air and blood to escape. After the canal is filled with cement in a retrograde fashion, the surgeons thumb is used to hold initial pressure while the cement gun is prepared for final pressurization

Figures 12.9A to C: The femoral seal is placed on the nozzle

(A) which is cut short so it will not slid into the canal during pressurization. (B) The seal is applied to the proximal femur and pressurization of the cement is done with slow steady pumps of the cement gun. It is crucial not to run out of cement during this process (C)

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of cement during this process as inadequate pressurization would result. Indicators of good pressurization are the absence of bleeding at the cement bone interface and extravasation of marrow contents from the proximal femoral bone (occurs even with good lavage technique). Also, cement will leak from under the seal. This is inevitable and desirable so long as the cement pressure does not drop due to an inadequate amount of cement.

Total Hip Arthroplasty

FEMORAL STEM INSERTION

The cement should be pressurized as described above prior to stem insertion. It is inappropriate to rely on stem insertion for pressurization of the cement; the implant should be merely positioned in place and held until the cement is polymerized. Once cement is adequately pressurized, the cement gun and femoral seal are removed and the stem is slowly inserted using steady manual pressure (Figs 12.10A to C). If a stem centralizer is used, the stem should not be inserted too late or the centralizer will cause defects in the cement mantle.38-41 The entry point for the stem is the same as for the broach, posterior and lateral, in line with the axis of the canal. The authors' preferred insertion handle for the stem is one that does not firmly fixate to the stem (screw-on) but does allow for rotational control. If the handle were to be firmly attached, any minor motion of the surgeon or leg would result in stem motion in the cement. If no centralizer is used, slight posterior pressure to direct the stem tip anteriorly will result in a central position of the stem. The stem should never be impacted into place. The stem is held in position while the cement hardens.

Smoother polished stems can be inserted later than matte or textured stems as the cement-implant interface is not disrupted from a smooth finish. The larger the stem size, the greater the volume of cement displaced by the implant; therefore, larger stems should be inserted earlier to allow for this amount of cement displacement.

A positive intraoperative sign of an adequate cement mantle is the absence of blood on the exposed bone of the femoral neck. The desired outcome is a blood free medial calcar followed by cement interdigitated into cancellous bone for 3 mm and an additional 2 mm of a pure cement mantle. Following this operative sequence will result in a routinely reproducible cement mantle with a Barrack-A radiographic grade free of voids and no radiolucencies occur (Fig. 12.11).42

Figures 12.10A to C: The stem is inserted and firmly held in position while the cement hardens (A). The appearance of an appropriate cement mantle is shown with a blood free medial calcar, 3 mm of cancellous cement interdigitation, and a 2 mm cement mantle adjacent to the implant (B). The pressurization curve with proximal and distal transducers is shown. If no thumb is applied after initial cementation then pressure falls to zero. The graph also shows that the stem insertion accounts for the majority of the distal pressurization while the femoral seal is more effective proximally (C)

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Cementing Technique: Femur

Figure 12.11: A Barrack A (white-out) cement mantle with adequate mantle thickness in all zones on both AP and lateral projections

FEMORAL GEOMETRY AND FIXATION OF FEMORAL COMPONENT

Dorr categorized the femur based on the geometry and cortical thickness of its proximal portion.43 A funnel shaped proximal femur with thick cortices is termed a Dorr A. A femur with a larger medullary canal and with medial and posterior cortical thinning is a Dorr B. As cortical thinning progresses, the femur takes on a "stovepipe" appearance having very thin cortices and a wide canal diameter, termed a Dorr C. Dorr A and B femora are suitable for cemented or cementless fixation. The capacious canal and fragile cortices of a Dorr C femur can preclude secure cementless fixation, and the senior author routinely cements the femoral implant in these cases.

GRADING OF CEMENT MANTLE

Barrack et al described a grading system for the appearance of the cement mantle on immediate postoperative radiographs.42 When no radiolucencies or mantle defects occur and the entire medullary canal of the femur is filled with cement, a "white-out" occurs, graded "A". When a slight radiolucency of the cement-bone interface occurs, a grade "B" mantle is achieved. Grade "C" is achieved when radiolucencies involve 50-99% of the cement-bone interface or when the cement mantle is incomplete. Grade "D" is used to describe the mantle when the medullary canal fails to fill with cement, often leaving the tip of the stem exposed, or when a complete 100% radiolucency of the cement-bone interface occurs.

Results

Although the use of cemented implants in THA is declining worldwide, the results of cemented hip arthroplasties show superior survivorship to cementless implants for many patient groups. Worldwide registry data supports the durability of cemented femoral stems. Cemented femoral implants have the lowest rate of revision for all age and gender groups in the National Joint Registry of England and Wales (NJREW). Even in the young male population (<55 years of age), cemented femoral implants have the lowest rate of revision, with hybrid fixation (uncemented acetabulum and cemented femur) having only a 2.6 percent revision rate at 5 years.44 The Australian Registry shows hybrid fixation to have the lowest overall revision rate with 4.5 percent at 9 years.45 Swedish Registry data shows superior results with cemented

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implants; cementation of both components yields the best results followed by hybrid fixation (cemented femur and uncemented acetabulum).46 No age, gender, or diagnosis group benefited from cementless fixation.47 Additionally, the Australian data show that risk of revision for cemented femurs does not vary with age.45 Meta-analysis results also support the use of cemented implants over cementless fixation.48 Although the results of many newer uncemented designs compare favorably with cemented results, these results are not yet proven in national registry databases that give results across the entire spectum of the population.

Conclusion

Cemented femoral fixation remains a highly successful procedure with excellent long term results. When applied properly, modern cementation technique as described helps and ensure that an adequate cement mantle of uniform thickness and devoid of voids is achieved. Meticulous femoral canal preparation, pressurization of cement, and positioning of femoral component in the centre of the cement mantle will lead to improved outcomes, and a decreased risk of failure/revision.

Figures 12.12A to C

Illustrative Case

Total Hip Arthroplasty

Pre-operative (A), immediate post-operative (B), and 5-year follow-up x-rays demonstrating a cemented femoral stem with excellent component position, and a Barrack grade A cement mantle (Figs 12.12A to C).

References

1. Association AO. Australian Orthopaedic Association National Joint Replacement Registry. Annual Report 2010. Adelaide: Australian Orthopaedic Association; 2010.

2. Morshed S, Bozic KJ, Ries MD, Malchau H, Colford JM Jr. Comparison of cemented and uncemented fixation in total hip replacement: a meta-analysis. Acta Orthop 2007;78(3):315-26.

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3. Hailer NP, Garellick G, Karrholm J. Uncemented and cemented primary total hip arthroplasty in the Swedish Hip Arthroplasty Register. Acta Orthop 2010;81(1):34-41.

4. Malchau H, Herberts P, Eisler T, Garellick G, Soderman P. The Swedish total hip replacement register. J Bone Joint Surg Am 2002;84-A Suppl 2:2-20.

5. Nation_Joint_Registry_of_England_and_Wales. Annual Report. 2008.

   Cementing Technique: Femur

6. Malchau H, Herberts P (Eds). Prognosis of total hip replacement. 65th Annual Meeting of the AAOS 2000; March 15-19; Orlando, USA.

7. Malchau H, Herberts P (Eds). Prognosis of total hip replacement; surgical and cementing technique in THR: a revision-risk study of 134 056 primary operations. 63rd Annual Meeting of the AAOS 1996; February 22-26; Atlanta, USA.

8. Breusch SJ, Norman TL, Schneider U, Reitzel T, Blaha JD, Lukoschek M. Lavage technique in total hip arthroplasty: Jet lavage produces better cement penetration than syringe lavage in the proximal femur. J Arthroplasty 2000;15(7):921-7.

9. Breusch SJ, Schneider U, Kreutzer J, Ewerbeck V, Lukoschek M. Effects of the cementing technique on cementing results concerning the coxal end of the femur. Orthopade 2000;29(3):260-70.

10. Breusch SJ, Schneider U, Reitzel T, Kreutzer J, Ewerbeck V, Lukoschek M. Significance of jet lavage for in vitro and in vivo cement penetration. Z Orthop Ihre Grenzgeb 2001;139(1):52-63.

11. Hu S, Zhang ZY, Hua YQ, Li J, Cai ZD. A comparison of regional and general anaesthesia for total replacement of the hip or knee: A meta-analysis. J Bone Joint Surg Br 2009;91(7):935-42.

12. Sieber FE, Zakriya KJ, Gottschalk A, Blute MR, Lee HB, Rosenberg PB, Mears SC. Sedation depth during spinal anesthesia and the development of postoperative delirium in elderly patients undergoing hip fracture repair. Mayo Clin Proc 2010;85(1):18-26.

13. Luger TJ, Kammerlander C, Gosch M, Luger MF, Kammerlander-Knauer U, Roth T, Kreutziger J. Neuroaxial versus general anaesthesia in geriatric patients for hip fracture surgery: does it matter? Osteoporos Int 2010;21(Suppl 4):S555-72.

14. Urwin SC, Parker MJ, Griffiths R. General versus regional anaesthesia for hip fracture surgery: A meta-analysis of randomized trials. Br J Anaesth 2000;84(4):450-5.

15. Noble PC, Alexander JW, Lindahl LJ, Yew DT, Granberry WM, Tullos HS. The anatomic basis of femoral component design. Clin Orthop Relat Res 1988;235:148-65.

16. Gruen TA, McNeice GM, Amstutz HC. Modes of failure of cemented stem-type femoral components: a radiographic analysis of loosening. Clin Orthop Relat Res 1979;141:17-27.

17. Johnston RC, Fitzgerald RH Jr, Harris WH, Poss R, Muller ME, Sledge CB. Clinical and radiographic evaluation of total hip replacement. A standard system of terminology for reporting results. J Bone Joint Surg Am 1990;72(2):161-8.

18. Breusch SJ, Lukoschek M, Kreutzer J, Brocai D, Gruen TA. Dependency of cement mantle thickness on femoral stem design and centralizer. J Arthroplasty 2001;16(5):648-57.

19. Wroblewski BM, Siney PD, Fleming PA, Bobak P. The calcar femorale in cemented stem fixation in total hip arthroplasty. J Bone Joint Surg Br 2000;82(6):842-5.

20. Draenert K DY, Garde U, Ulrich Ch. Manual of cementing technique. Berlin, Heidelberg, New York, Tokyo, Springer, 1999.

21. DiGiovanni CW, Garvin KL, Pellicci PM. Femoral preparation in cemented total hip arthroplasty: reaming or broaching? J Am Acad Orthop Surg 1999;7(6):349-57.

22. Ling RS. Observations on the fixation of implants to the bony skeleton. Clin Orthop Relat Res 1986;210:80-96.

23. Newman MA BW, Hayes DE Jr, Taylor JK, (Ed). Femoral canal preparation for cemented stems: reamers versus broaches. 60th Annual Meeting of the American Academy of Orthopaedic Surgeons; 1993 February, San Francisco, USA.

24. Valdivia GG, Dunbar MJ, Parker DA, Woolfrey MR, MacDonald SJ, McCalden RW, Rorabeck CH, Bourne RB. The John Charnley Award: Three-dimensional analysis of the cement mantle in total hip arthroplasty. Clin Orthop Relat Res 2001;393:38-51.

25. Joshi RP, Eftekhar NS, McMahon DJ, Nercessian OA. Osteolysis after Charnley primary low-friction arthroplasty. A comparison of two matched paired groups. J Bone Joint Surg Br 1998;80(4):585-90.

26. Kwak BM, Lim OK, Kim YY, Rim K. An investigation of the effect of cement thickness on an implant by finite element stress analysis. International Orthopaedics 1978;2(4):315-9.

27. Lee AJ, Ling RS. Improved cementing techniques. Instr Course Lect 1981;30:407-13.