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Copyright (c) 2022 Slovenian Medical Journal. This work is licensed under a
Creative Commons Attribution-NonCommercial 4.0 International License.
Comparison of the clinical outcome after total hip 
endoprosthesis via the direct anterior or lateral 
approach: a systematic review with metaanalysis
Primerjava kliničnega izida vstavitve totalne endoproteze kolka preko  
anteriornega in lateralnega pristopa: sistematični pregled z metaanalizo
Samo Roškar,1,2 Rihard Trebše1,2
Abstract
Background: The total hip endoprosthesis is one of the most successful elective surgical procedures in orthopaedic sur-
gery. The choice of a surgical approach importantly influences the outcome of the intervention and globally, there is a 
preference towards the lateral approach. However, the direct anterior approach is gaining popularity, primarily due to less 
soft tissue trauma than in the lateral approach.
Methods: Our meta-analysis only included randomised control trials, which were selected from three English databases: 
PubMed, Cochrane Library, and Clinical Trials. The search was performed in December 2019. Information on country, sam-
ple size, intervention, outcome, and follow-up period has been extracted. The meta-analysis was performed using Review 
Manager 5.3.
Results: Seven randomized controlled trials totalling 723 patients were included. Comparing direct anterior and lateral 
approach to the total hip arthroplasty, no difference was found in the functional status graded using the Harris hip score at 
the end of follow-up, pain reported with visual analogue scale in the early and late postoperative period, blood loss, need 
for transfusion, length of hospital stay and appearance of the intra- and postoperative complications.
Conclusions: Comparison of the direct anterior and the lateral approach shows that there is no significant difference be-
tween the two approaches in functional status, pain reported in the early and late postoperative period, blood loss, need 
for transfusion, length of hospital stays, and occurrence of the intra- and postoperative complications. To date, there is no 
randomized controlled trial directly comparing clinical outcomes between the two approaches with a well-determined 
protocol.
1 Valdoltra Orthopaedic Hospital, Ankaran, Slovenia
2 Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
Correspondence / Korespondenca: Samo Roškar, e: samo.roskar@ob-valdoltra.si
Key words: total hip arthroplasty; lateral approach; direct anterior approach; clinical outcome; metaanalysis
Ključne besede: totalna endoproteza kolka; stranski pristop; neposredni sprednji pristop; klinični izid; metaanaliza
Received / Prispelo: 11. 10. 2020 | Accepted / Sprejeto: 11. 3. 2021
Cite as / Citirajte kot: Roškar S, Trebše R. Comparison of the clinical outcome after total hip endoprosthesis via the direct anterior or 
lateral approach: a systematic review with metaanalysis. Zdrav Vestn. 2022;91(5–6):226–36. DOI: https://doi.org/10.6016/ZdravVestn.3179
eng slo element
en article-lang
10.6016/ZdravVestn.3179 doi
11.10.2020 date-received
11.3.2021 date-accepted
Surgery, orthopaedics, traumatology Kirurgija, ortopedija, travmatologija discipline
Systematic review Sistematični pregledni članek article-type
Comparison of the clinical outcome after total 
hip endoprosthesis via the direct anterior or 
lateral approach: a systematic review with 
metaanalysis
Primerjava kliničnega izida vstavitve totalne en-
doproteze kolka preko anteriornega in lateralnega 
pristopa: sistematični pregled z metaanalizo
article-title
Comparison of the clinical outcome after total 
hip endoprosthesis via the direct anterior or 
lateral approach
Primerjava kliničnega izida vstavitve totalne en-
doproteze kolka preko anteriornega in lateralnega 
pristopa
alt-title
total hip arthroplasty, lateral approach, direct 
anterior approach, clinical outcome, meta-
analysis
totalna endoproteza kolka, stranski pristop, ne-
posredni sprednji pristop, klinični izid, metaanal-
iza
kwd-group
The authors declare that there are no conflicts 
of interest present.
Avtorji so izjavili, da ne obstajajo nobeni 
konkurenčni interesi. conflict
year volume first month last month first page last page
2022 91 5 6 226 236
name surname aff email
Samo Roškar 1,2 samo.roskar@ob-valdoltra.si
name surname aff
Rihard Trebše 1,2
eng slo aff-id
Valdoltra Orthopaedic Hospital, 
Ankaran, Slovenia
Ortopedska bolnišnica Valdoltra, 
Ankaran, Slovenija 1
Faculty of Medicine, University 
of Ljubljana, Ljubljana, Slovenia
Medicinska fakulteta, Univerza v 
Ljubljani, Ljubljana, Slovenija 2
Slovenian Medical Journallovenian Medical Journal
227
SYSTEMATIC REVIEW
Comparison of the clinical outcome after total hip endoprosthesis via the direct anterior or lateral approach
1 Introduction
Total hip arthroplasty (THA) is one of the most 
common and successful elective procedures in or-
thopaedic surgery. It is the treatment of choice in ad-
vanced osteoarthritis regardless of the cause, signifi-
cantly improving an individual’s quality of life (1). The 
development of the THA protocol has enabled shorter 
hospital stays, faster rehabilitation and greater patient 
satisfaction with the procedure. Among the important 
factors influencing the improvement of THA success 
rate is the choice of surgical approach (2). Particular-
ly in Europe, the lateral approach (LA) is probably the 
most commonly used; worldwide, it is used by approx-
imately 42% of surgeons (3). The posterior approach, 
slightly more popular in the United States than in 
Europe, is also commonly used. The downside of the 
lateral approach is the need for at least a partial disin-
sertion, damaging the muscles during the approach to 
the joint (4). In contrast to LA, the direct anterior ap-
proach (DAA) has recently become more popular, but 
is currently performed by significantly fewer surgeons 
than LA (3). When describing DAA, most authors have 
the patient in the supine position; however, certain au-
thors note the patient in the lateral decubitus position. 
For the anterior approach, a normal operating table or 
a specialized extension table are used; with the latter, 
the table allows hip hyperextension. In DAA, the inci-
sion is normally oblique, 2–4 cm distally and laterally 
to the anterior superior iliac spine (ASIS) to a few cen-
timetres before the major trochanter. This is followed 
Izvleček
Izhodišča: Totalna endoproteza kolka velja za enega najuspešnejših posegov v ortopedski kirurgiji. Pomemben dejavnik 
vpliva na izid je izbira kirurškega pristopa. Trenutno je v svetu najbolj razširjen stranski pristop, v zadnjem času pa postaja 
zaradi manj poškodb mehkih tkiv vse bolj priljubljen sprednji pristop.
Metode: V sistemski pregled smo vključili randomizirane kontrolirane raziskave iz podatkovnih baz PubMed in Cochrane 
Library ter raziskave, prijavljene pri Clinical Trials. Iskanje smo opravili decembra 2019. Zabeležili smo podatek o državi, 
velikosti vzorca, posegu, izidu in času spremljanja. Metaanalizo smo opravili s programom Review Manager 5.3.
Rezultati: V metaanalizo smo vključili 7 randomiziranih kontroliranih raziskav s 723 preiskovanci. Med sprednjim in stran-
skim pristopom totalne endoproteze kolka ni razlik v funkcionalnem stanju, vrednotenem po Harrisu ob koncu spremlja-
nja, v oceni bolečine po vizualni analogni lestvici tako v zgodnjem kot poznem obdobju po operaciji, v izgubi krvi, v potrebi 
po transfuziji, v trajanju bolnišnične oskrbe in v pojavnosti zapletov med operacijo in po njej.
Zaključki: Primerjava sprednjega in stranskega pristopa kaže, da med pristopoma ni statistično pomembnih razlik v funk-
cionalnem stanju ob koncu spremljanja, v oceni bolečine tako v zgodnjem kot poznem obdobju po operaciji, v izgubi krvi, 
v potrebi po transfuziji, v trajanju bolnišnične oskrbe in v pojavnosti zapletov med operacijo in po njej. Trenutno ne poteka 
nobena randomizirana kontrolirana raziskava, ki bi primerjala izid sprednjega in stranskega pristopa z natančno zastavlje-
nim protokolom spremljanja.
by the appearance of the fascia of the tensor fasciae 
latae muscle under the subcutaneous tissue, which is 
incised longitudinally. Blunt dissection in the interval 
between the sartorius and lateral tensor fasciae latae 
muscles enables access to the hip joint (5). DAA pro-
ponents argue that unlike LA, DAA results in less soft 
tissue damage because the joint is accessed between 
muscles and in the plane between nerves. Proponents 
of LA, on the other hand, argue that it allows for a bet-
ter hip joint visualization and is associated with a low 
complication rate (4). Several randomized controlled 
trials (RCTs) are currently available comparing DAA 
and LA (6-12). Most of these have small sample sizes 
and report different outcomes. So far, four meta-analy-
ses comparing DAA and LA have been conducted (13-
16). In their meta-analysis, Yue et al included RCTs 
and other types of clinical research. In their conclu-
sion, they report that current evidence is insufficient 
to determine which approach is better (14). Putanon et 
al also included the posterior approach alongside DAA 
and LA in their network meta-analysis. By indirectly 
comparing individual approaches in the meta-analy-
sis, they concluded that DAA was superior, followed 
by LA (15). In their meta-analysis, Kucukdurmaz et al 
compared DAA with other approaches and, based on 
indirect comparisons, concluded that DAA provided 
the best functional outcome in the early postoperative 
period, while after six weeks, there was no difference 
between individual approaches (16). However, in their 
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Figure 1: PRISMA diagram of the meta-analysis selection process.
Publications aer duplicate removal 
(n = 288)
Identification of
publications in PubMed 
andCochrane Library 
(n = 290)
Review of publications 
(n = 288)
Full text 
review 
(n = 7)
Publications included 
in further analysis 
(n = 7)
Excluded publications
(n = 281)
Excluded publications 
aer a full text review 
(n = 0)
Id
e
n
ti
fi
ca
ti
o
n
R
e
vi
e
w
R
e
le
va
n
ce
In
cl
u
si
o
n
Publications included 
in the meta-analysis 
(n = 7)
Additionally identified 
publications in other sources 
(n = 0)
meta-analysis, Wang et al compared only DAA and 
LA. The study concluded that in DAA, a trend towards 
less pain and blood loss was seen compared to LA, but 
further RCTs with larger sample sizes are needed to 
confirm this (13).
The problem with all meta-analyses to date is that 
in addition to RCTs, they include other types of clini-
cal studies or compare all three THA approaches, per-
forming only an indirect comparison of DAA and LA. 
None of the meta-analyses to date include an addition-
al review of ongoing research in this field reported to 
the Clinical Trials database. The aim of our meta-anal-
ysis is to review the current RCTs comparing LA and 
DAA and to further analyze the ongoing research on 
the comparison between LA and DAA, included in the 
Clinical Trials database.
2 Materials and methods
The systematic review with meta-analysis 
was performed in accordance with the PRISMA 
recommendations (Preferred Reporting Items for Sys-
tematic Reviews and Meta-Analyses (Figure 1).
2.1 Literature search
Publications in English from the PubMed and Co-
chrane Library databases were included in the system-
atic review. We conducted the search in December 
2019. We used the following search string: (“Arthro-
plasty, Replacement, Hip [MeSH Terms]” OR “THA” 
OR “THR” OR “total hip replacement” OR “total hip 
arthroplasty”) AND (“direct anterior approach «OR» 
anterior approach «OR» anterior »OR» Hueter ap-
proach «OR» Smith-Petersen approach «OR» lateral 
approach «OR» Hardinge approach”).
Additionally, we included currently ongoing re-
search comparing DAA and LA in the systematic re-
view. A search of the Clinical Trials database of the 
National Institute of Health (NIH) was conducted in 
December 2019. We used “total hip arthroplasty” and 
“total hip replacement” for the search strings.
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Comparison of the clinical outcome after total hip endoprosthesis via the direct anterior or lateral approach
Legend of monitored outcomes: 1 − functional state; Harris hip score (HHS); 2 – pain assessment with a visual analogue scale 
(VAS); 3 – surgery duration; 4 – intraoperative blood loss; 5 – need for transfusion; 6 – hospitalization duration; 7 – incidence of 
intraoperative and postoperative complications. DAA – direct anterior approach; LA – lateral approach; BMI – body mass index; 
RCT − randomized controlled trial.
State DAA LA Mean 
age
Proportion 
of women 
(%)
BMI Outcome Study 
type
Follow-up 
duration
Mayr 2009 Austria 16 17 66.9 66 25.6 2, 3, 4 RCT 3 months
Resterpo 2010 USA 50 50 67.2 70 27.6 1, 3, 4, 5, 6, 7 RCT 4 years
Mjalaand 2015 Norway 84 80 66.9 66 27.6 1, 2, 3, 4, 5 RCT Until discharge
Parvizi 2016 USA 50 50 72.4 62 28 4, 6 RCT 1 year
Zomar 2018 Canada 36 42 60.2 52 27.9 1, 2, 6 RCT 3 months
Brismar 2018 Sweden 50 50 66.5 65 27.8 3, 4, 6, 7 RCT 5 years
Reichert 2018 Germany 77 71 62.6 43 28.2 1, 2, 7 RCT 1 year
Table 1: General characteristics of studies, included in the meta-analysis.
2.2 Inclusion criteria
1. Subjects: Patients with clinically and radiologically 
confirmed advanced osteoarthritis of the hip joint.
2. Procedure: THA with DAA.
3. Control: THA with LA.
4. Recorded outcome: functional outcome deter-
mined by the Harris hip score (HHS) at the end 
of follow-up, duration of surgery, blood loss, need 
for transfusion, duration of hospitalization, visual 
analogue scale (VAS) pain assessment and the in-
cidence of THA-related complications.We included 
all studies that recorded at least one of the identified 
outcomes.
5. Study design: RCT.
2.3 Choice of studies
Studies for the meta-analysis were selected by one 
of the authors. Based on a review of the title and ab-
stract and defined inclusion criteria, they decided to 
select studies that were then reviewed in their entirety. 
Data for meta-analysis were obtained from the results 
reported in each published article.
2.4 Data acquisition
Data in included studies include: general study 
characteristics (authors, year of publication, country, 
number of subjects, mean age of subjects, proportion of 
female subjects, body mass index - BMI), recorded re-
sults (HHS, VAS, duration of surgery, blood loss, need 
for transfusion, duration of hospitalization, THA com-
plications incidence) and follow-up duration.
2.5 Statistical analysis
Statistical analysis was performed with Review 
Manager 5.3 software (The Cochrane Collaboration, 
Copenhagen, Denmark). The statistical significance 
was set at a p-value ≤ 0.05. The odds ratio (OR) with 
a 95% confidence interval (CI) was calculated for dis-
crete variables, need for transfusion and incidence of 
complications, while the mean difference and 95% CI 
were used for continuous variables. In cases of statis-
tically insignificant heterogeneity between individu-
al studies (I2 <50%), we used the fixed effects model. 
However, when high sample heterogeneity (I2 ≥ 50%) 
was identified, the random effects model was used.
3 Results
3.1 Meta-analysis characteristics
During the search and selection of relevant pub-
lished studies for our meta-analysis, we found 290 
publications by searching databases. Based on the in-
clusion criteria, we excluded 281 studies. Finally, we 
fully reviewed and included data from seven studies 
(6-12). General characteristics of the included studies 
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Principal 
investigator
Year of 
application
State Study 
type
Expected 
sample size
Inclusion criteria Status
Hozack 2009 USA RCT 100 All with hip arthrosis Finished, without publication
Sorladent Hospital HF 2012 Norway RCT 120 Persons 20 – 80 years old with hip arthrosis
Ongoing, does not 
currently include patients
Viorel Nistor 2016 Romania RCT 100 Persons 35 – 80 years old with hip arthrosis Still including patients
Table 2: Currently ongoing studies comparing the direct anterior approach (DAA) and lateral approach (LA), included in 
the Clinical Trials database.
Figure 2: Forest plot of the functional state, assessed with the Harris hip score (HHS) in THA with the direct anterior 
approach (DAA) and lateral approach (LA).
DAA below the graph means that the functional state, assessed with HHS, is better with DAA; when LA is below the graph, the 
functional state is better with it.
Legend: SD – standard deviation; IV – inverse variance; random – random effects model; 95% CI − 95% confidence interval; 
df – degrees of fredom.
are shown in Table 1. A total of 723 subjects were in-
cluded in the meta-analysis. Of these, 363 underwent 
THA with DAA and 360 with LA. All included studies 
were published between 2009 and 2018.
During the search of ongoing studies in the Clinical 
Trials database, we found 733 registered studies with 
the “total hip arthroplasty” string and 712 studies with 
the “total hip replacement” string. After exclusion of 
inconsistent or overlapping studies and studies that did 
not fit our inclusion criteria, we included three studies 
in our meta-analysis (Table 2) (17-19).
3.2 Evaluation of individual outcomes
3.2.1 Functional outcome defined by the Harris 
hip score at the end of follow-up
At the end of follow-up, HHS was reported by five 
studies involving 590 subjects (297 DAA and 293 LA). 
At the end of the study, there was no statistically signif-
icant difference in the functional status of patients who 
underwent DAA or LA (mean difference = 0.97, 95% 
CI (-1.13; 3.08), p = 0.37) (Figure 2).
3.2.2 Pain assessment with the visual analogue 
scale
Pain assessment with VAS was reported by four 
studies involving 375 subjects (186 DAA and 189 LA). 
Among the study groups, the VAS assessment at dis-
charge showed no difference in pain intensity between 
the two approaches, both in the early postoperative 
period and later during follow-up. On discharge from 
hospital, the mean difference was –0.49, 95% CI (–1.86; 
0.88), p = 0.49; after six weeks of follow-up, the mean 
difference was 0.02, 95% CI (–0.99; 1.03), p = 0.97; after 
12 weeks of follow-up, the mean difference was 0.13, 
95% CI (–0.12; 0.37), p = 0.68 (Figure 3).
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Comparison of the clinical outcome after total hip endoprosthesis via the direct anterior or lateral approach
Figure 3: Forest plot of pain assessment with VAS in THA with the direct anterior approach (DAA) and lateral approach (LA).
VAS, recorded at discharge, six weeks after surgery and 12 weeks after surgery.
DAA below the graph means that the VAS-assessed pain was lesser with DAA; when LA is below the graph, pain is lesser with it.
Legend: SD – standard deviation; IV – inverse variance; random – random effects model; 95% CI − 95% confidence interval; 
df – degrees of freedom.
Figure 4: Forest plot of the surgery duration in THA with the direct anterior approach (DAA) and lateral approach (LA).
DAA below the graph means that the surgery duration was shorter with DAA; when LA is below the graph, the surgery duration 
was shorter with it.
Legend: duration in minutes; SD – standard deviation; IV – inverse variance; random – random effects model; 95% CI − 95% 
confidence interval; df – degrees of freedom.
3.2.3 Surgery duration
The data on surgery duration was reported by five 
studies involving 497 subjects (DAA 250 and LA 247). 
Among the study groups, LA had a slightly shorter 
surgery duration (mean difference = 6.97 min, 95% CI 
(–3.54; 17.45), p = 0.19), but the difference was not 
statistically significant (Figure 4).
3.2.4 Intraoperative blood loss and the need for 
transfusion
Intraoperative blood loss was reported by five studies 
involving 497 subjects (DAA 250 and LA 247). The com-
parison of the study groups did not show a statistically 
significant difference (mean difference = –28.93 ml, 95% 
CI (–68.06; 10.20), p = 0.15) (Figure 5).
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Figure 5: Forest plot of  recorded blood loss in THA with the direct anterior approach (DAA) and lateral approach (LA).
DAA below the graph means that blood loss was less extensive with DAA; when LA is below the graph, blood loss was less 
extensive with it.
Legend: mean blood loss in mililitres; SD – standard deviation; IV – inverse variance; random – random effects model; 95% CI − 
95% confidence interval; df – degrees of freedom.
Figure 6: Forest plot of the need for transfusion in THA with the direct anterior approach (DAA) and lateral approach (LA).
DAA below the graph means that transfusion was less frequently needed with DAA; when LA is below the graph, transfusion 
was not needed as frequently with it.
Legend: SD − standard deviation; M-H − Mantel-Haenszel test; fixed – fixed effects model; 95% CI − 95% confidence interval; 
df – degrees of freedom.
The need for transfusion was reported by two stud-
ies involving 164 subjects (DAA 134 and LA 130). A 
comparison of the study groups showed no statistically 
significant difference (odds ratio = 0.8, 95% CI (0.38; 
1.67), p = 0, 55) (Figure 6).
3.2.5 Duration of hospitalization
The duration of hospitalization after surgery was 
reported by four studies involving 387 subjects (DAA 
186, LA 201). There was no statistically significant dif-
ference in the duration of hospitalization after THA 
(mean difference = –0.63 days, 95% CI (–1.27; 0.00), p 
= 0.05) (Figure 7).
3.2.6 Incidence of complications
Complications associated with THA were reported 
by five studies involving 582 subjects (DAA 290 and LA 
292). The reported complications vary between authors. 
Complications of DAA include transient lateral femoral 
cutaneous nerve sensory abnormalities and early hip 
dislocation, which is treated with closed reduction. In 
both approaches, superficial and deep infections, dif-
ferences in leg length greater than one centimetre and 
fractures have been reported. Complications in LA in-
clude hip abductor insufficiency, gluteus minimis and 
medius disinsertion and late dislocation with the need 
for open reduction with internal fixation. There was 
no statistically significant difference in the incidence 
of complications during and after surgery between the 
study groups (odds ratio = 1.17, 95% CI (0.7; 1.95), p = 
0.56) (Figure 8).
4 Discussion
4.1 Main findings
In our systematic review of the literature with a me-
ta-analysis, we found that individual studies included 
comparable patient populations. Only patients with 
primary hip osteoarthritis were included in all studies, 
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Comparison of the clinical outcome after total hip endoprosthesis via the direct anterior or lateral approach
Figure 7: Forest plot of the hospitalization duration in THA with the direct anterior approach (DAA) and lateral approach 
(LA).
Legend: hospitalization duration, defined as the number of hospital days after the procedure; SD – standard deviation; IV – 
inverse variance; random – random effects model; 95% CI − 95% confidence interval; df – degrees of freedom.
DAA below the graph means that the hospitalization duration after THA was shorter with DAA; when LA is below the graph, the 
hospitalization duration after THA was shorter with it.
Figure 8: Forest plot of  intraoperative and postoperative surgery complications in THA with the direct anterior approach 
(DAA) and lateral approach (LA).
DAA below the graph means that there were less complications with DAA; when LA is below the graph, there were less surgery 
complications with it.
Legend: SD − standard deviation; M-H − Mantel-Haenszel test; fixed – fixed effects model; 95% CI − 95% confidence interval; 
df – degrees of freedom.
their mean age ranged from 60 to 70 years; the stud-
ies included a higher proportion of women than men, 
and the mean BMI ranged from 25 to 30 kg/m2. Our 
meta-analysis, which compared THA with DAA ver-
sus LA, found that there was no statistically significant 
difference between the approaches to THA. The me-
ta-analysis showed that there was no difference be-
tween HHS at the end of follow-up, pain assessment 
with VAS in both early and late postoperative peri-
ods, blood loss, need for transfusions, and incidence 
of complications during and after surgery. Only in the 
duration of hospitalization after THA was the differ-
ence between DAA and LA on the border of statistical 
significance (p = 0.05), with the two studies included 
in our meta-analysis showing statistically significant-
ly shorter hospital stays with DAA compared to LA 
(6,12).
4.2 Comparison with other meta-analyses
So far, four meta-analyses have been published com-
paring different THA approaches (13-16). In addition 
to RCTs, most included other types of clinical research. 
They compared all three THA approaches, performing 
only an indirect comparison of DAA and LA. None of 
the meta-analyses to date included an additional re-
view of relevant ongoing studies included in the Clinical 
Trials database. Only one of the previous meta-analy-
ses directly compared DAA and LA and included only 
RCTs, analyzing five RCTs with 457 subjects (13). Our 
meta-analysis included seven RCTs with a total of 723 
subjects. Although Yue et al published a meta-analysis 
of 12 studies with a total of 4,901 subjects, they included 
cohort studies in addition to the RCTs (14). In their me-
ta-analysis, Wang et al reported that DAA was associated 
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with significantly less blood loss and less pain six weeks 
after surgery. For the other variables considered, there 
were no significant differences between DAA and LA in 
previous or our meta-analysis (12). Our meta-analysis 
differs significantly from previous ones in that it deals 
only with RCTs that compare only DAA and LA. Ad-
ditionally, our meta-analysis provided an overview of 
currently ongoing studies included in the Clinical Trials 
database, which are the basis for new publications in this 
field in the near future.
4.3 Clinical significance of findings
Like Wang et al, our meta-analysis found that 
there was no difference between DAA and LA in the 
HHS-evaluated functional status of patients at the end 
of follow-up (13). It is important to emphasize the 
fact that all meta-analyses of functional status, includ-
ing ours, compared HHS, estimated at different times 
during follow-up, which ranged from a few days (time 
to discharge) to five years between individual studies. 
Individual studies assessed HHS at different points in 
time without a uniform time of recording HHS. In stud-
ies that monitored the functional status of patients with 
HHS for a longer period of time, we observed that in 
the early postoperative period, HHS was higher when 
DAA was used, while after a longer follow-up period, 
there were no differences in HHS between DAA and 
LA (6,10,11). Thus, in their study, Zomar et al reported 
that the functional outcome, evaluated with HSS, was 
statistically significantly better with DAA compared to 
LA; the patients were followed for up to three months af-
ter discharge (12). However, the remaining studies with 
clinical follow-up durations of more than a year did not 
report a difference in functional outcome between DAA 
and LA.
In an analysis of pain assessment, Wang et al found 
less VAS-assessed pain in the early postoperative period 
in the DAA group (13). When reviewing the literature, 
we found that in the original article by Mjalaand et al, 
we were unable to decipher data on pain assessment 
with VAS pain six months after THA, which Wang et 
al included in their meta-analysis. In pain assessment 
with VAS after six weeks, Mayr et al showed that with 
DAA, there was less pain, while Zomar and co-workers 
showed less pain with LA (7,12). After 12 weeks, how-
ever, only Zomar et al found less pain with LA (12). 
Our meta-analysis includes three studies reporting pain 
assessment with VAS at discharge and after six and 12 
weeks, with no differences between the two approaches. 
Based on varying assessments of pain, we can only say 
that further research and a longer duration of follow-up 
are required to differentiate between the degree of post-
operative pain with DAA or LA.
Similar to previous meta-analyses, we did not find 
statistically significant differences in surgery duration 
between DAA and LA (13-16). It should be noted that 
individual studies, included in the meta-analysis, did 
not report the surgeon’s experience with DAA. Studies 
to date have shown that the surgeon’s experience is im-
portant, particularly for DAA (13). In our meta-analysis, 
we found that Mjalaand et al and Brismar et al reported 
shorter surgery durations with LA compared to DAA; 
the first study involved five surgeons, each with at least 
several hundred performed surgeries, and the second 
included two surgeons, each with at least 40 performed 
surgeries (6,8).
In contrast to previous meta-analyses, which show 
statistically significantly lower blood loss in THA with 
DAA compared to LA (13,14), our meta-analysis did 
not find statistically significant differences in recorded 
intraoperative blood loss between the approaches. Ad-
ditionally, similar to previous meta-analyses, no statis-
tically significant difference in the need for transfusion 
was found between the two approaches (13).
Like Wang et al, our meta-analysis did not reveal sta-
tistically significant differences in hospitalization dura-
tion, with the inclusion of recent studies by Risterp et 
al and Reichert et al (10,11,13). It is worth noting the 
difference in the reported hospitalization duration be-
tween European and American studies, as the mean hos-
pitalization duration after THA is on average longer in 
Europe than in the US (6,9,11,12).
In our study, similarly to previous meta-analyses, due 
to their low incidence, we could not avoid combining 
intraoperative and postoperative complications. Com-
plications of DAA include transient lateral femoral cu-
taneous nerve sensory abnormalities and early hip dis-
location, which is treated with closed reduction. In both 
approaches, superficial and deep infections, differences 
in leg length greater than one centimetre and fractures 
have been reported. Complications in LA include hip 
abductor insufficiency, gluteus minimis and medius 
disinsertion and late dislocation with the need for open 
reduction with internal fixation. Similar to previous me-
ta-analyses, we find that there are no statistically signif-
icant differences in the incidence of complications be-
tween DAA and LA (13).
A review of the Clinical Trials database shows that no 
randomized clinical trial is currently underway that in-
cludes a sufficiently large sample size and has a well-de-
fined follow-up protocol for both groups (17-19). A 
235
SYSTEMATIC REVIEW
Comparison of the clinical outcome after total hip endoprosthesis via the direct anterior or lateral approach
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review of the database revealed that a cohort multicentre 
study was reported in May 2011, which was expected to 
include 500 DAA, 100 LA, and 100 posterior THA ap-
proaches (20). The survey is currently noted to be com-
pleted with only 50 patients included, but without fur-
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meta-analyses and our meta-analysis, to more precisely 
define the differences between DAA and LA, we need 
new, larger RCTs, which will consistently measure indi-
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4.4 Limitations
Our meta-analysis included only seven RCTs with a 
total of 723 subjects with conflicting study results. With 
the availability and inclusion of more RCTs, even small-
er differences between DAA and LA could be identified. 
There were important differences in the recording of 
outcomes between the individual studies we included, as 
comparable outcomes only partially overlapped. Most of 
the included studies had a short follow-up period, with 
only two surveys following subjects for more than one 
year. Among the limitations of our meta-analysis, it is 
important to note that not all studies included indicated 
the level of experience of the surgeons involved in each 
study, which can have a significant impact on the record-
ed outcome.
5 Conclusion
Comparison of THA approaches (DAA and LA) 
shows that there are no statistically significant differenc-
es in functional status at the end of follow-up, early and 
late postoperative pain, blood loss, need of transfusion, 
duration of hospitalization and the incidence of intraop-
erative and postoperative complications. A review and 
meta-analysis of previous studies shows that in order to 
more accurately identify possible differences between 
DAA and LA, we need new, larger RCTs that will con-
sistently measure individual variables. A review of on-
going reported studies shows that no RCTs are currently 
underway that compare DAA and LA outcomes with a 
well-defined follow-up protocol. A RCT is still missing 
that would focus specifically on trochanteric pathology, 
which is an important source of persistent symptoms af-
ter THA, but is still completely unexplored in terms of 
approach.
Conflict of interest
None declared.
236
SURGERY, ORTHOPAEDICS, TRAUMATOLOGY
Zdrav Vestn | May – June 2022 | Volume 91 | https://doi.org/10.6016/ZdravVestn.3179
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