Abstract
In recent years, the use of larger heads has become popular in total hip arthroplasty. This development is the consequence of dislocation being cited as the second most frequent reason for revision and also of high patient expectations with respect to function of their hip replacement. Larger heads have been shown to be an effective measure against dislocation and also have the potential to increase range of motion. However, larger heads always increase the joint friction moment, thereby challenging component fixation in the femur and in the acetabulum. Since larger heads are also associated with greater wear when articulating against polyethylene, there has been a shift to hard-on-hard bearing articulations. In simulators, metal-on-metal bearings demonstrated a particular decrease in wear with increasing head diameter. Initially, it was not appreciated that in situations of poor lubrication and edge loading, the benefit of larger heads is lost, with an increased risk of revision. Large-diameter metal-on-metal bearing couples demonstrated an especially marked increase in revision rates due to cup loosening, excessive metal debris, or taper issues. The challenge now is to find a balanced head size that reduces the rate of early revision due to dislocation, as well as late revision due to lysis, loosening, and other wear debris-related problems. The evidence suggests that the compromise could be a diameter of 32 or 36 mm, depending on the bearing articulation.
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1 Large Heads in Hip Arthroplasty
The head size in total hip arthroplasty (THA) has always been a topic of controversy. Although it is undisputed that Charnley established the replacement of the hip joint as a standard procedure with his philosophy of “low friction arthroplasty” relying on a small head diameter (22.25 mm) [9], the use of larger heads has never lost its attraction for appealing reasons: greater stability and increased range of motion (Fig. 1.1). At the same time, the disadvantages of increasing the head diameter have always been recognized: higher friction moments and greater wear in hard-soft bearing articulations, which can lead to a higher revision rate. A comparison between the Charnley and Mueller prostheses more than 30 years ago reported better results for the Charnley type, “possibly due to the smaller head” [42]. Nevertheless, as long as the National Joint Replacement Registry of the Australian Orthopaedic Association reports “loosening / lysis and dislocation of prosthesis components” as the two most common reasons for revision (29 and 23 %, respectively [4]), the desire for larger heads will continue (Fig. 1.2). This became very clear by the rapid adoption of larger head sizes in England and Wales between 2003 and 2011: the use of the “traditional” head size of 28 mm decreased by nearly 50 % during this period, while the use of larger diameters increased (Fig. 1.3). This increase was driven by two achievements: the improvement of the wear characteristics of polyethylene (PE) by highly cross-linking (HX-PE) and the renewed popularity of hip resurfacing (HR) with large metal-on-metal (MoM) articulations, initiated by Derek McMinn and Harlan Amstutz [3, 32]. The design surgeons and manufactures were convinced that the problems that had led to failure of large MoM bearings more than 30 years previously had been recognized and resolved with the new designs. Due to the advantages of large heads early postoperatively, many surgeons followed this rapid development. The consequence of this “hype” is now hitting the orthopedic community hard: MoM articulations and HR have nearly disappeared from the market as a consequence of high revision rates in the registries in comparison with conventional THAs. Adverse responses to metallic debris arising from wear and corrosion, generated either at the bearing articulation and/or the taper interface between head and stem or elevated metal ions in blood or serum, are the dominant reasons for these revisions.
This chapter discusses the potential advantages of large-diameter heads in THA, critically weighing clinical observations with the potential benefits.
2 Head Size and Metal-on-Metal Bearing Articulations
Three different prosthesis types can be differentiated for MoM bearings (Fig. 1.4): modular small heads (≤32 mm) THA, modular large heads (≥36 mm), and hip resurfacing arthroplasty. The definition of 36 mm as a cutoff between small and large is somewhat arbitrary and some sources also categorize 36 mm as the largest small head. The three different types show quite different performance in clinical application (Fig. 1.5). The small head modular MoM bearings have been used quite successfully for the last 25 years and show revision rates similar to other conventional bearing articulations. Large head modular MoM bearings demonstrate poor performance, and several authors suggest omitting them completely in the future based on the registry results [44]. A European consensus statement explicitly warns against this type of MoM bearing [18]. Larger modular heads have also been shown to exhibit more fretting and crevice corrosion at the head taper interface [13]. This seems to occur if the head is not sufficiently fixed on the stem taper. This seems to be the origin of the increased serum metal ion concentrations and revision rates observed for large-diameter modular MoM bearings in comparison with large-diameter HR [4, 15]. In the worst case, this can result in fracture of the stem taper, typically close to the open end of the head taper (Fig. 1.6). High friction moments in the joint articulation in adverse lubrication situations may generate micromotions at the taper junction between head and stem [7] or cup loosening [30, 33]. This friction increase with head diameter is pronounced for MoM and ceramic-on-ceramic (CoC) articulations and further enhanced by the negative effect of resting periods on start-up friction (Fig. 1.7) [7, 8, 35].
In HR, the tendency is the opposite: smaller-diameter resurfacing components show an increased risk for revision [21] and higher blood Co and Cr ion concentrations [38]. Two primary factors are cited to explain the contrasting behavior between HR and large head modular MoM THA: firstly, a smaller angle of coverage for smaller monoblock acetabular cups resulting in a higher risk of edge loading and increased wear [16] and secondly different failure mechanisms in women, who tend to have smaller femoral head diameters [20].
In preclinical testing, larger MoM heads outperformed smaller ones. The resulting design objective was to minimize clearance and increase diameter to optimize wear behavior [12]. The partial success of these HR designs in preclinical testing were misleading, since the overall clinical revision rate for HR is much higher than for small-diameter modular MoM THAs. A recent study voices concerns even for well-functioning HR bearings. Differences in bone and cardiac function between patient groups suggest that chronic exposure to low elevated metal concentrations in patients with well-functioning HR prostheses may have systemic effects [41]. Furthermore, patients with unexplained hip pain leading to revision of a metal-on-metal hip arthroplasty sometimes exhibit satisfactory acetabular cup orientation and low wear rates, which are the factors typically associated with problems [19]. This is the basis for Hart’s speculation that patient-specific factors may have been responsible for the failure in a large proportion of these patients. With all these problems, large THA MoM bearings, be they modular or HR, have more or less disappeared from the market.
3 Range of Motion
Some of the most commonly claimed reasons for the use of large heads are the improved range of motion (RoM) and function. During normal daily activities, the RoM utilized is quite substantial: flexion/extension can reach up to 124°, abduction/adduction up to 28°, and internal/external rotation up to 33° [23]. During athletic activities such as running, cycling, kick boxing, alpine skiing, wrestling, or free climbing, which are being practiced by some patients with THA (as claimed on the homepages of the respective companies), the RoM is most certainly higher.
The achievable range of motion is limited by impingement between femoral neck and acetabular rim and is determined by prosthesis design as well as component positioning. Head size directly influences this technical RoM. Component positioning determines the “zero” point of the RoM, i.e., how much of the RoM in flexion-extension is actually usable for flexion. Increasing the head size from 28 to 36 mm yields an increase of 13° in the technical RoM (from 123° to 136°). This applies to a hemispherical cup with a modern 12/14 mini taper completely embedded in the head and a slender neck design (proximal neck diameter smaller than the distal diameter of the taper). The technical RoM is not directly related to the active or passive RoM achieved by the patient. The “true” RoM of the patient is heavily influenced by the orientation of the components, the muscular and soft tissue situation. The limit to the RoM is reached, when the neck of the stem impinges on the cup or pelvic bone or when bony impingement occurs somewhere else between femur and pelvis.
Clinically, the theoretical advantage of larger head sizes is not really reflected. Prosthetic design has been shown to be unlikely as a limiting factor to the range of motion, provided that the positioning of the acetabular component is adequate [29]. One year after surgery, increased head size was shown not to improve function [1, 17], and range of motion was not increased at 2 years postoperatively [39]. The benefit of increased RoM of larger heads seems to be limited by the bony anatomy [25]. Extra-large-diameter femoral components may cause iliopsoas impingement, which might be the cause of postoperative pain [10]. These reports demonstrate that the increased technical RoM of larger heads is not directly related to the clinically observed RoM and function and therefore an improved RoM is not a sufficient argument for the use of large heads.
4 Dislocation Risk
Nearly all publications document a decrease in the dislocation rate for an increase in head diameter (Fig. 1.8). The absolute numbers, however, are quite different. For heads with a 28 mm diameter (Fig. 1.5), they range over 0.6 % [5], 2.0 % [24], 2.5 % [40], 3.0 % [6], 3.1 % [2], and 3.6 % [37]. For smaller head diameters, the range is even greater: 3.8 % [6] to 18.8 % [37] for a 22 mm head. For larger head diameters, the rates are very low: for heads with 32 mm diameter only 0.5 % [2], and even 0.0 % for 38 mm [40]. This indicates that the head diameter itself is only partly responsible for the dislocation rate. Implant position and soft tissue tension achieved by the surgeon are probably equally, or even more, important: “The theoretical gain in stability obtained by using a large femoral head (above 36 mm) is negligible in cases where there is a high cup abduction angle [43].” Already in 2004, Roy Crowninshield stated that the use of larger femoral heads contributes little to joint stability but elevates the stress within the polyethylene with high abduction acetabular component orientation [11]. The role of combined anteversion [34] and high preoperative range of motion [27] as well as several other factors besides head size was shown to be important for dislocation risk (Paprowsky acetabulum classification, hip abductor deficiency [46]). In excessively obese patients, it was even shown that a reduced cup abduction angle more effectively reduces dislocation risk than head diameter [14].
Considering the advantages and disadvantages of large heads, the important question becomes: How large does it have to be? The 2013 annual joint registry report of the Australian Orthopaedic Association makes a very clear statement in this regard: “Smaller head sizes (less than 32 mm) have the highest rate of revision for dislocation in all age groups. Increasing head size from 32 to 36 mm or larger does not appear to confer any additional protection against revision for dislocation.”
5 Final Remarks
Considering the pros and cons of large and extra-large heads, it is proposed that the head diameter should be limited to about 36 mm in primary hip arthroplasty – the “36 and under club” founded in 2008 by Carsten Perka from the Charité in Berlin and the first author of this paper is still appropriate; in hard-on-soft bearings utilizing polyethylene, the limit should possibly be 32 mm, since for hard-on-soft bearings wear increases with head diameter. The superior wear characteristics of cross-linked PE reduces but does not remove the increase in wear with increasing head diameter [28]. Larger heads also require thinner inserts, which have shown higher PE wear rates in simulators [22]. In CoC bearings, wear is not influenced by head diameter, but larger heads have been found to generate a greater rate of noises. A recent study of large ceramic-on-ceramic designs reported 21 % squeaking [31]. Thinner ceramic liners have not been reported to have a higher fracture risk than thicker liners if implanted correctly (Fig. 1.9).
Larger heads reduce the early dislocation rate due to dislocation. However, in the long term, larger heads have been shown to have a greater cumulative revision rate after 9–21 years [45]. An analysis of the Finnish Arthroplasty Register recently showed a reduced risk for dislocation (−90 %) but a higher revision rate (+2 %) after 10 years for head diameters above 36 mm [26].
Total hip arthroplasty is the most successful surgical intervention in the history of orthopedics. The growing number of surgeries performed every year and the success rates in the registries confirm this. From a biomechanical and materials point of view, established prosthesis designs are safe and have the potential to achieve good results in the vast majority of patients over periods in excess of 15 years, as long as patient and surgeon act carefully and responsibly. There is a continuing need to improve implants and utilize newly available materials, but in this process, the risks and side effects of new developments must be carefully considered without focusing purely on the benefits. Continuous surgeon education and training for new implants and procedures is an essential requirement for the introduction of any new development into the clinics. The present problems with large MoM bearings and taper issues have once more demonstrated that successful preclinical testing does not guarantee clinical success but rather comprises a minimal requirement. Novel failure mechanisms, which never appeared in the past, cannot be prevented by preclinical testing, which is based on known problems. The international standards should be extended to include testing of adverse implant conditions rather than considering only the optimal situation. However, even this will not remove the need for a stage-wise clinical introduction of new designs. The challenge in the future will be to differentiate designs that should be categorized as “new.”
In summary, there is compelling evidence that larger heads can effectively reduce the early dislocation and revision rates and that smaller heads reduce late revision due to osteolysis and loosening. A sensible choice of the optimum head diameter for the individual patient (as outlined before: not above 32 with X-PE or 36 mm with CoC in primary THA) combined with accurate component positioning will help to further improve the results of total hip arthroplasty.
References
Allen CL, Hooper GJ, Frampton CM. Do larger femoral heads improve the functional outcome in total hip arthroplasty? J Arthroplasty. 2013 [Epub before print].
Amlie E, Hovik O, Reikeras O. Dislocation after total hip arthroplasty with 28 and 32-mm femoral head. J Orthop Traumatol. 2010;11(2):111–5.
Amstutz HC, Le Duff MJ. Background of metal-on-metal resurfacing. Proc Inst Mech Eng H. 2006;220(2):85–94.
Australian Orthopaedic Association. National Joint Replacement Registry. Annual Report. Adelaide: AOA; 2012.
Archbold HA, Slomczykowski M, Crone M, Eckman K, Jaramaz B, Beverland DE. The relationship of the orientation of the transverse acetabular ligament and acetabular labrum to the suggested safe zones of cup positioning in total hip arthroplasty. Hip Int. 2008;18(1):1–6.
Berry DJ, von Knoch M, Schleck CD, Harmsen WS. Effect of femoral head diameter and operative approach on risk of dislocation after primary total hip arthroplasty. J Bone Joint Surg Am. 2005;87(11):2456–63.
Bishop NE, Hothan A, Morlock MM. High friction moments in large hard-on-hard hip replacement bearings in conditions of poor lubrication. J Orthop Res. 2013;31(5):807–13.
Bishop NE, Waldow F, Morlock MM. Friction moments of large metal-on-metal hip joint bearings and other modern designs. Med Eng Phys. 2008;30(8):1057–64.
Charnley J. Low friction arthroplasty of the hip. Berlin: Springer; 1979.
Cobb JP, Davda K, Ahmad A, Harris SJ, Masjedi M, Hart AJ. Why large-head metal-on-metal hip replacements are painful: the anatomical basis of psoas impingement on the femoral head-neck junction. J Bone Joint Surg Br. 2011;93(7):881–5.
Crowninshield RD, Maloney WJ, Wentz DH, Humphrey SM, Blanchard CR. Biomechanics of large femoral heads: what they do and don’t do. Clin Orthop Relat Res. 2004;429:102–7.
Dowson D. Tribological principles in metal-on-metal hip joint design. Proc Inst Mech Eng H. 2006;220(2):161–71.
Dyrkacz RM, Brandt JM, Ojo OA, Turgeon TR, Wyss UP. The influence of head size on corrosion and fretting behaviour at the head-neck interface of artificial hip joints. J Arthroplasty. 2013;28:1036–40.
Elkins JM, Daniel M, Pedersen DR, Singh B, Yack HJ, Callaghan JJ, Brown TD. Morbid obesity may increase dislocation in total hip patients: a biomechanical analysis. Clin Orthop Relat Res. 2013;471(3):971–80.
Garbuz DS, Tanzer M, Greidanus NV, Masri BA, Duncan CP. The John Charnley Award: metal-on-metal hip resurfacing versus large-diameter head metal-on-metal total hip arthroplasty: a randomized clinical trial. Clin Orthop Relat Res. 2010;468(2):318–25.
Griffin WL, Nanson CJ, Springer BD, Davies MA, Fehring TK. Reduced articular surface of one-piece cups: a cause of runaway wear and early failure. Clin Orthop Relat Res. 2010;468(9):2328–32.
Hanna SA, Sewell MD, Sri-Ram K, Miles J, Aston WJ, Pollock RC, Carrington RW, Briggs TW. The effect of femoral head size on functional outcome in primary total hip arthroplasty: a single-blinded randomised controlled trial. Hip Int. 2012;22(6):592–7.
Hannemann F, Hartmann A, Schmitt J, Lutzner J, Seidler A, Campbell P, Delaunay CP, Drexler H, Ettema HB, Garcia-Cimbrelo E, Huberti H, Knahr K, Kunze J, Langton DJ, Lauer W, Learmonth I, Lohmann CH, Morlock M, Wimmer MA, Zagra L, Gunther KP. European multidisciplinary consensus statement on the use and monitoring of metal-on-metal bearings for total hip replacement and hip resurfacing. Orthop Traumatol Surg Res. 2013;99:263–71.
Hart AJ, Matthies A, Henckel J, Ilo K, Skinner J, Noble PC. Understanding why metal-on-metal hip arthroplasties fail: a comparison between patients with well-functioning and revised birmingham hip resurfacing arthroplasties. AAOS exhibit selection. J Bone Joint Surg Am. 2012;94(4):e22.
Hinsch A, Vettorazzi E, Morlock MM, Ruther W, Amling M, Zustin J. Sex differences in the morphological failure patterns following hip resurfacing arthroplasty. BMC Med. 2011;9:113.
Jack CM, Walter WL, Shimmin AJ, Cashman K, de Steiger RN. Large diameter metal on metal articulations. Comparison of total hip arthroplasty and hip resurfacing arthroplasty. J Arthroplasty. 2013;28(4):650–3.
Johnson AJ, Loving L, Herrera L, Delanois RE, Wang A, Mont MA. Short-term wear evaluation of thin acetabular liners on 36-mm femoral heads. Clin Orthop Relat Res. 2014;472(2):624–9.
Johnston R, Smidt G. Hip motion measurements for selected activities of daily living. Clin Orthop Relat Res. 1970;72:205–15. Ref Type: Journal (Full).
Khatod M, Barber T, Paxton E, Namba R, Fithian D. An analysis of the risk of hip dislocation with a contemporary total joint registry. Clin Orthop Relat Res. 2006;447:19–23.
Klingenstein GG, Yeager AM, Lipman JD, Westrich GH. Increased range of motion to impingement with large head total hip arthroplasty: point of diminishing returns. Hip Int. 2012;22(3):261–5.
Kostensalo I, Junnila M, Virolainen P, Remes V, Matilainen M, Vahlberg T, Pulkkinen P, Eskelinen A, Makela KT. Effect of femoral head size on risk of revision for dislocation after total hip arthroplasty. Acta Orthop. 2013;84(4):342–7.
Krenzel BA, Berend ME, Malinzak RA, Faris PM, Keating EM, Meding JB, Ritter MA. High preoperative range of motion is a significant risk factor for dislocation in primary total hip arthroplasty. J Arthroplasty. 2010;25(6 Suppl):31–5.
Lachiewicz PF, Heckman DS, Soileau ES, Mangla J, Martell JM. Femoral head size and wear of highly cross-linked polyethylene at 5 to 8 years. Clin Orthop Relat Res. 2009;467(12):3290–6.
Le Duff MJ, Wisk LE, Amstutz HC. Range of motion after stemmed total hip arthroplasty and hip resurfacing – a clinical study. Bull NYU Hosp Jt Dis. 2009;67(2):177–81.
Long WT, Dastane M, Harris MJ, Wan Z, Dorr LD. Failure of the Durom Metasul acetabular component. Clin Orthop Relat Res. 2010;468(2):400–5.
McDonnell SM, Boyce G, Bare J, Young D, Shimmin AJ. The incidence of noise generation arising from the large-diameter Delta Motion ceramic total hip bearing. Bone Joint J. 2013;95-B(2):160–5.
McMinn D, Treacy R, Lin K, Pynsent P. Metal on metal surface replacement of the hip. Experience of the McMinn prothesis. Clin Orthop Relat Res. 1996;(329 Suppl):S89–S98.
Morlock MM, Bishop N, Zustin J, Hahn M, Ruther W, Amling M. Modes of implant failure after hip resurfacing: morphological and wear analysis of 267 retrieval specimens. J Bone Joint Surg Am. 2008;90 Suppl 3:89–95.
Nakashima Y, Hirata M, Akiyama M, Itokawa T, Yamamoto T, Motomura G, Ohishi M, Hamai S, Iwamoto Y. Combined anteversion technique reduced the dislocation in cementless total hip arthroplasty. Int Orthop. 2014;38(1):27–32.
Nassutt R, Wimmer MA, Schneider E, Morlock MM. The influence of resting periods on friction in the artificial hip. Clin Orthop Relat Res. 2003;407:127–38.
National Joint Registry. 9th Annual Report for England and Wales; 2012. www.njrcentre.org.uk
Padgett DE, Lipman J, Robie B, Nestor BJ. Influence of total hip design on dislocation: a computer model and clinical analysis. Clin Orthop Relat Res. 2006;447:48–52.
Parry MC, Eastaugh-Waring S, Bannister GC, Learmonth ID, Case CP, Blom AW. Blood levels of cobalt and chromium are inversely correlated to head size after metal-on-metal resurfacing arthroplasty. Hip Int. 2013;23(6):529–34.
Penny JO, Ovesen O, Varmarken JE, Overgaard S. Similar range of motion and function after resurfacing large-head or standard total hip arthroplasty. Acta Orthop. 2013;84(3):246–53.
Peters CL, McPherson E, Jackson JD, Erickson JA. Reduction in early dislocation rate with large-diameter femoral heads in primary total hip arthroplasty. J Arthroplasty. 2007;22(6 Suppl 2):140–4.
Prentice JR, Clark MJ, Hoggard N, Morton AC, Tooth C, Paley MN, Stockley I, Hadjivassiliou M, Wilkinson JM. Metal-on-metal hip prostheses and systemic health: a cross-sectional association study 8 years after implantation. PLoS One. 2013;8(6):e66186.
Ritter MA, Stringer EA, Littrell DA, Williams JG. Correlation of prosthetic femoral head size and/or design with longevity of total hip arthroplasty. Clin Orthop Relat Res. 1983;176:252–7.
Sariali E, Lazennec JY, Khiami F, Catonne Y. Mathematical evaluation of jumping distance in total hip arthroplasty: influence of abduction angle, femoral head offset, and head diameter. Acta Orthop. 2009;80(3):277–82.
Smith AJ, Dieppe P, Vernon K, Porter M, Blom AW. Failure rates of stemmed metal-on-metal hip replacements: analysis of data from the National Joint Registry of England and Wales. Lancet. 2012;379(9822):1199–204.
Tarasevicius S, Kesteris U, Robertsson O, Wingstrand H. Femoral head diameter affects the revision rate in total hip arthroplasty: an analysis of 1,720 hip replacements with 9–21 years of follow-up. Acta Orthop. 2006;77(5):706–9.
Wetters NG, Murray TG, Moric M, Sporer SM, Paprosky WG, la Valle CJ. Risk factors for dislocation after revision total hip arthroplasty. Clin Orthop Relat Res. 2013;471(2):410–6.
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Morlock, M.M., Huber, G., Bishop, N. (2014). Large-Diameter Total Hip Replacement Bearings. In: Knahr, K. (eds) Tribology in Total Hip and Knee Arthroplasty. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-45266-6_1
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