uncemented. While this may have a bearing on operativetime, and by extrapolation, an effect on the complica-tion rate, it was not thought to be a likely major con-founding factor within the context of this study.
Literature ReviewSeveral previous studies have compared bilateral se-quential and simultaneous groups, but no study has yetbeen published using only one cemented femoral com-ponent type. Eggli, Huckell, and Ganz (1996) concludedthat there was no difference in complication rates, butthat the simultaneous procedure resulted in a reducedlength of hospital stay and its associated cost. This studyincluded relatively large numbers: 128 hips in the simul-taneous group and 382 hips in the sequential group. Thelimitations of this study were the use of different pros-thesis and the short-term follow-up (mean follow-up of1.5 years). Another study by Parvizi et al. (2006) reportedreduced length of stay with the simultaneous procedureand, in addition, showed higher complication rates inthe sequential group. This study only evaluated unce-mented stems. A further study by Alfaro-Adrian, Bayona,Rech, and Murray (1999) advocated the simultaneousprocedure but accepted that there was an associatedhigher blood transfusion rate. Again, this study includedmore than one stem type. Macaulay et al. (2002) ac-cepted that in medically fit patients, postoperative com-plications are within acceptable limits in simultaneousbilateral operations, but stated that complication ratescan be 1.3 times higher in this group in comparison to
The aim of this study was to compare the outcomes ofbilateral sequential versus bilateral simultaneous hip replace-ments, using the collarless polished taper cemented hipprosthesis, in relation to complications, revisions, patientsatisfaction rates, and Harris Hip Score. Data were collectedby independent practitioners and processed within theUniversity Audit Department. A total of 594 patients wereidentified as having undergone bilateral hip replacementsurgery. Patient satisfaction rates were consistently high inboth groups. Harris Hip Scores improvements were similarand reflected a marked improvement in pain and function.The sequential bilateral group experienced an increasedlength of hospital stay and therefore potential cost implica-tions, which may be offset by the lower incidence of ad-verse events. Bilateral simultaneous hip replacement re-mains an important option, for which there is strongsupportive evidence.
More than 43,000 hip replacements are car-ried out in the UK National Health Serviceevery year. It is one of the most commonand effective surgical procedures per-
formed in the field of orthopaedics. Single-stage bilat-eral operations, which have the advantages of reducedhospital stay, one anesthetic session, and the subse-quently reduced costs, are becoming increasingly com-mon. However, there are concerns regarding the degreeof surgical trauma to the body, increased blood loss,and the impact these may have on existing comorbidi-ties. Macaulay, Salvati, Sculco, and Pellicci, (2002) pre-viously reported that single-stage bilateral operationsshould be contraindicated in patients with significantcomorbidities such as heart disease and diabetes.
This study compared bilateral sequential and bilat-eral simultaneous hip replacements with a single hipsystem: collarless polished taper. The design principlesof this system have been used for more than 30 years inthe treatment of osteoarthritis, rheumatoid arthritis,and other disabling conditions of the hip. The acetabu-lar components are a combination of cemented and
Bilateral Simultaneous HipReplacement Versus BilateralSequential Hip ReplacementA 7-Year Data Review
Linda R. Johnston ▼ Benedict A. Clift ▼ Rami J. Abboud
RESEARCH
Linda R. Johnston, RGN, BN, MSc, Department of Orthopaedic andTrauma Surgery, University of Dundee, TORT Centre, Ninewells Hospital,Dundee, Scotland.
Benedict A. Clift, BMSc (Hons), MBChB, FRCS Ed, FRCS Orth, Directorateof Orthopaedic and Trauma Surgery, Ninewells Hospital, Dundee, Scotland.
Rami J. Abboud, BEng, MSc, PhD, SMIEEE, ILTM, Department ofOrthopaedic and Trauma Surgery, University of Dundee, TORT Centre,Ninewells Hospital, Dundee, Scotland.
The authors have disclosed that they have no financial interests to anycommercial company related to this educational activity.
unilateral surgery. Lorenze, Huo, Zatorski, and Keggi(1998) reported no differences between bilateral sequen-tial and simultaneous groups in perioperative complica-tions but highlighted the reduced length of stay associ-ated with the simultaneous procedure. One limitation ofthis study was that it included only 40 patients in eachgroup. Berend et al. (2005) used similar outcome mea-sures but only compared bilateral simultaneous to uni-lateral hip arthroplasty. Their study showed prostheticsurvival to be similar in both groups, with no differencein Harris Hip Scores (HHS). However, an increased riskof thromboembolic complications in the simultaneousbilateral group implied that this procedure should per-haps be performed on patients with no significant co-morbidities. Deep infection rates in bilateral sequentialand simultaneous groups have been reported to be simi-lar (Huotari, Lyytikainen, & Seitsalo, 2007).
Materials and MethodsData were extracted from a multicenter hip database.Bilateral cases dated back to 1993, so operations from1993 to 2005 were included. This database contains dataon hip systems collected by independent practitionersand processed within our clinical audit services unit.Surgeons participate in this outcome study to monitortheir own performance, the performance of the prosthe-ses used, and patient satisfaction. All patients of the 32participating surgeons from 10 centers throughout theUnited Kingdom admitted for elective hip arthroplastysurgery consented for electronic storage of their dataand subsequent usage for dissemination. Each centerhad a clinical audit practitioner, who was trained by asingle coordinator to collect the data according to a sin-gle protocol. This multiplicity of surgeons and centersavoids drawing conclusions on the basis of an isolatedpractice in a single “center of excellence.” It therefore isrelevant to everyday orthopaedic practice.
Preoperative baseline information and HHS, as de-scribed by Harris (1969), were collected by independentclinical audit practitioners. The same fully trained inde-pendent practitioner then reviewed patients at 1, 3, 5,and 7 years postoperatively. HHS, complications, revi-sions, and patient satisfaction were recorded at each re-view. Patient satisfaction was ascertained by asking pa-tients whether they were happy with their surgery and ifnot why not. From the database, 594 patients were iden-tified as having undergone bilateral hip replacementsurgery. The simultaneous group comprised 68 patients(26 men and 42 women) with the sequential group hav-ing 526 (208 men and 318 women). The sequentialgroup had more patients as it is presently much lesscommon to perform bilateral simultaneous hip replace-ment surgery than bilateral sequential staged surgery inthe United Kingdom.
STATISTICAL METHODS
Variables were explored for distribution and extremevalues. Plausible normality of distribution was deter-mined using the Shapiro–Wilks test. Outlying datapoints were identified and investigated.
Where appropriate, confidence intervals for quantita-tive variables in each group (sequential and simultaneous),
and the difference between them, were established.Repeated-measures analysis of variance was applied toHHS at pre- and postoperative reviews. The within-subjects factor was Review and the between-subjectsfactor was Group. Variables with extreme values wereinvestigated using the Mann-Whitney U test. Categoricalvariables were investigated using chi-square methods.
ResultsThe demographics of patients in the sequential andsimultaneous groups were similar (see Table 1). Theproportions of men and women in the sequential andsimultaneous groups were comparable (39.5% male inthe sequential group and 38.2% in the simultaneousgroup; p � .84). Patients in the sequential group wereslightly older than those in the simultaneous group(mean age � 66.5 and 61.5 years, respectively; p � .001),but both groups lay firmly within the “standard” agerange for the procedure.
The sequential group had a lower percentage of pa-tients with Charnley classification C (bilateral diseasewith comorbidities); 76% compared with 93% in the si-multaneous group. This may reflect the practice of somesurgeons in offering a single operation to less-healthypatients, in the belief that this may lead to less cumula-tive morbidity than two operations, particularly in thecontrolled environment of the operating theatre. Clearlythe simultaneous group did not include carefully se-lected healthier patients.
The mean BMI for each group was in the overweightrange but comparable across groups (27.2 and 27.4 forsequential and simultaneous patients, respectively; p �.78). As can be expected, the preoperative HHS scoreswere in the poor range with marginally higher scores inthe sequential group, however not significantly different.At 1 year postoperatively, HHS scores were improvedsignificantly with slightly higher scores in the sequentialgroup (82.2 [0.5] falling in the good range) compared to
TABLE 1. DEMOGRAPHICS AND OUTCOMES OF PATIENTS IN
SEQUENTIAL AND SIMULTANEOUS PATIENTS (QUANTITATIVE)
Number Parameter Replacement of Cases Mean (SE)
Age Sequential 526 66.5 (0.5)*Simultaneous 68 61.5 (1.3)
Body mass index Sequential 512 27.2 (0.2)Simultaneous 68 27.4 (0.6)
the simultaneous group (78.9 [1.8] falling in the fairrange). This difference was significant at the p � .04level. In looking at HHS improvement scores, the differ-ence between the 1 year and the preoperative score wascalculated. Improvements in HHS at 1 year were compa-rable (41.4 and 42.3, respectively; p � .66) across groups.At 3- and 5-year reviews, HHS was comparable in bothgroups with mean scores falling in the good range. The7-year review for the simultaneous group had HHS of79.5 in comparison with 83.2 for the sequential group,but the numbers were small (see Table 1).
There were several exceptional lengths of stay ineach of the two groups that were attributable to compli-cations. Including extremes, the median stay in the se-quential and simultaneous groups were 9 and 13.5 days,respectively (p � .001). When cases with complicationswere excluded, median stays were 9 and 12 days, respec-tively (p � .001). Because of the long-term follow-up in-volved in this study, some operations dated back to1993, thus explaining the long lengths of stay. The meanlength of stay of patients operated on for a primary hipreplacement in 1993 was 15.9 days in comparison with8.9 days in 2005.
Satisfaction rates are displayed as a percentage ofthose who answered that they were satisfied with theirsurgery against those who were not satisfied. This ques-tion was asked at each review period. There were no sig-nificant between-group differences in satisfaction ratesat any postoperative review (see Table 2). However, pa-tients who underwent sequential hip replacement wereless likely to have adverse events, as shown by the lowerpercentage of readmissions (see Table 2). With the ex-ception of superficial infection, these differences werenot statistically significant.
The incidence of superficial wound infection in thesimultaneous group was 5.8% (4 cases of 68) in compar-ison with 1.5% (8 cases of 526) in the sequential group.This difference was statistically significant (p � .04).There were no cases of thromboembolic episodes in thesimultaneous group although 8 cases (1.5%) occurredin the sequential group. The dislocation rate in the si-multaneous group was 5.8% and 3.2% in the sequentialgroup. Dislocation rates of 14.5% at 10-year follow-up
have been reported using the Trent regional arthro-plasty register (Allami et al., 2006).
DiscussionThe results from our collarless polished taper datashowed a reduced length of stay but an increased inci-dence of adverse events in the simultaneous bilateralgroup. This is consistent with the findings of other studies.
The incidence of superficial wound infection in thesimultaneous group was 5.8% in comparison with 1.5%in the sequential group. Our finding differs from that ofHuotari et al. (2007), who reported no between-groupdifference regarding infection.
An increase in the incidence of thromboembolicepisodes in the simultaneous group has been suggestedin the literature. Deep venous thrombosis (DVT) rates of2.8% and 9.1% have been recorded after unilateral totalhip replacement (Sudo et al., 2003; White, Romano,Zhou, Rodrigo, & Bargar, 1998). None was recorded inthe simultaneous group in our study, although 1.5%occurred in the sequential group. Many surgeons citeanecdotal evidence of increased thromboembolic prob-lems in patients with bilateral surgery as a reason not toperform it. The present study suggests that this view isnot supported by the evidence.
The dislocation rate in the sequential group waslower than that in the simultaneous group (3.2% com-pared with 5.8%) and those rates reported previously,but much lower than those reported in the Trent reg-istry after long-term review (Allami et al., 2006; Khatod,Barber, Paxton, Namba, & Fithian, 2006; Meek, Allan,Mcphillips, Kerr, & Howie, 2006).
The rate of revision appeared higher in the simultane-ous group, because of a single case having a fall resultingin a periprosthetic femoral fracture. Reasons for revi-sion in the sequential group were infection, groin paindue to leg lengthening, and femoral fracture after a fall.
Interestingly, the mean preoperative HHS for thesimultaneous group was lower (see Table 1), implying aslightly more disabled patient group in terms of pain andfunction. This also is supported by the fact that thesimultaneous group had 93% patients with Charnley
TABLE 2. DEMOGRAPHICS AND OUTCOMES OF PATIENTS IN SEQUENTIAL AND SIMULTANEOUS GROUPS (QUALITATIVE)
Parameter Replacement Percentages Significance
Satisfaction at 1 year Sequential 97 p � .37Simultaneous 95
Satisfaction at 3 years Sequential 96 p � .51Simultaneous 92
Satisfaction at 5 years Sequential 97 p � .35Simultaneous 100
Readmissions at 1 year Sequential 24 p � .65Simultaneous 27
Readmissions at 3 years Sequential 11 p � .52Simultaneous 17
Readmissions at 5 years Sequential 25 p � .65Simultaneous 29
Revisions at 1 year Sequential 0.8 p � .55Simultaneous 1.5
classification C, indicating the presence of comorbiditiesin comparison with 76% in the sequential group, whichhad 15% of patients with Charnley classification A, withsimultaneous group having none. Thus, simultaneousbilateral procedures were performed on patients withmore comorbidities than the sequential group. This iscontrary to what may be expected.
The strengths of this study are the use of a single pro-tocol, independent assessors, independent analysis, andone type of femoral stem for all patients (see Figure 1),thus reducing bias from confounding factors. The limi-tations are the relatively small numbers in the simulta-neous group and the participation of more than one sur-geon, which may have resulted in the use of differentapproaches and surgical techniques. In addition, morein-depth information could have been collected on ex-isting comorbidities. It would also have been of interestto ascertain any nursing care issues related to simulta-neous bilateral operations. There was an increased dis-location rate in the simultaneous group, but only oneoccurred during the acute hospital stay.
ConclusionSequential bilateral surgery is performed more commonlythan simultaneous bilateral surgery in the UnitedKingdom. While there are cost implications with in-creased length of stay for the sequential bilateral group,this may be offset by the lower incidence of adverse events.
Patient satisfaction rates were consistent and high inboth simultaneous and sequential groups. HHS im-provements were also similar and reflected a markedimprovement in pain and function. These results do notshow any major problem with either approach to thecommon clinical presentation of bilateral hip arthritis.Authoritative statements that either the sequential orthe simultaneous procedure is better seem unjustified.The decision is likely to continue to be based upon sur-geon and patient preference, rather than on dubiousclaims related to either mortality or cost, both of whichare often cited within the surgical community.
ACKNOWLEDGMENTS
The authors have no professional or financial affilia-tions that may be perceived to have biased the presenta-tion. The authors thank the contributing surgeons foraccess to their anonymized data.
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