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 Table of Contents  
ORIGINAL ARTICLE
Year : 2023  |  Volume : 6  |  Issue : 1  |  Page : 27-31

Effect of surgical approach on functional outcome and component positioning in total hip arthroplasty


Department of Orthopaedics, Nizam's Institute of Medical Sciences, Hyderabad, Telangana, India

Date of Submission23-Apr-2022
Date of Decision03-Jul-2022
Date of Acceptance03-Sep-2022
Date of Web Publication27-Dec-2022

Correspondence Address:
Sreekanth Kashayi-Chowdojirao
Associate Professor, Department of Orthopaedics, Nizam's Institute of Medical Sciences, Hyderabad, Telangana
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jodp.jodp_37_22

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  Abstract 


Context: Total hip arthroplasty (THA) is commonly performed through a posterior or a direct lateral (Hardinge) approach, and each one has merits and demerits. Aims: The purpose of this study was to examine the difference between the lateral and posterior approaches with respect to functional outcome, component positioning, intraoperative blood loss, and patient satisfaction. Settings and Design: This is a prospective comparative study of short- to mid-term outcome of cementless THA using two approaches. Subjects and Methods: Seventy hips satisfying our inclusion criteria were selected, of which 21 hips operated by lateral approach in supine position were included in lateral approach group (LAG), and 49 hips operated by posterior approach in lateral position were included in posterior approach group (PAG). Functional assessment was performed 1 day before surgery, 1 year after surgery, and at the latest follow-up using Harris Hip score (HHS). Component positioning of acetabular cup and femoral stem was assessed in plain radiographs at the latest follow-up. Generic satisfaction questionnaire was used to measure satisfaction after THA at the latest follow-up. Radiographic measurements (cup inclination, cup version, and femoral stem tip position) were performed postoperatively using low-centered pelvic anteroposterior and cross-table lateral hip radiographs. Results: At an average of 3 years and 6 months of follow-up, the mean HHSs were 88.05 and 90.32, respectively, in LAG and PAG; the difference was not significant (P = 0.178). The average inclination of the cup in LAG was 37.9° and in PAG was 45.02° with a significant difference (P = 0.00027), both of which are in the normal range. The cups were significantly (P ≤ 0.0001) more anteverted in the PAG (average angle of 27.69° vs. 16.14°). The mean blood loss was significantly more in PAG (510 ml vs. 436.67 ml; P = 0.04). Majority of femoral stems in lateral approach had their tips directed posterior. Nineteen out of 21 LAG patients and 45 out of 49 PAG were very satisfied/satisfied with their outcomes after THA. Statistical Analysis Used: Data were collected using prestructured data forms and analyzed with unpaired Student's t-test with 95% confidence interval. Conclusions: There was no significant difference in functional outcome and patient satisfaction at short- to mid-term follow-up between both approaches. The cup anteversion was significantly more in PAG. For better conclusions, other factors (i.e. immediate postoperative pain, and long-term survival), combined anteversion and spinopelvic parameters, have to be included in the study with a larger sample size.

Keywords: Cup anteversion, cup inclination, functional outcome, lateral approach, patient satisfaction, posterior approach, stem tip position, total hip arthroplasty


How to cite this article:
Kashayi-Chowdojirao S, Khazi Syed AH, Boddeda S, Patnala C. Effect of surgical approach on functional outcome and component positioning in total hip arthroplasty. J Orthop Dis Traumatol 2023;6:27-31

How to cite this URL:
Kashayi-Chowdojirao S, Khazi Syed AH, Boddeda S, Patnala C. Effect of surgical approach on functional outcome and component positioning in total hip arthroplasty. J Orthop Dis Traumatol [serial online] 2023 [cited 2023 Jan 30];6:27-31. Available from: https://jodt.org/text.asp?2023/6/1/27/365277




  Introduction Top


Osteoarthritis of the hip (OA), secondary to avascular necrosis (AVN) of the head of femur, is a progressive joint disease causing pain, reduced physical function, and reduced quality of life. Total hip arthroplasty (THA) provides pain reduction and improves physical function and quality of life in most patients with end-stage hip OA.[1],[2] In the US, 427,000 hip replacements are performed each year, and the incidence is expected to increase due to the growing elderly population.[3],[4] Of the various surgical approaches for THA,[5],[6],[7],[8],[9],[10],[11],[12] two of the most commonly used approaches are the direct lateral[8] (Hardinge approach) and the posterior (Southern, Moore, Gibson, or posterolateral[7]) approaches. A Cochrane review by Jolles and Bogoch[13] concluded that despite numerous studies examining the effect of surgical approach in THA, they were insufficient to enable a firm conclusion regarding whether one approach was superior to the other. Of the four prospective cohort studies included in the Cochrane review, only one study by Barber et al.[2] included functional outcomes using Harris Hip Score (HHS) with a short follow-up of 2 years and involving only 49 patients. The effect of surgical approach on dislocation rates after primary THA also has been the primary focus of numerous studies.[14],[15],[16] Pellicci et al.[17] reported no incidence of posterior dislocation in 395 patients operated by the posterior approach, when they used an enhanced posterior soft tissue repair. Downing et al.[18] reported that the lateral approach, though it gives an excellent exposure, disturbance of the abductor mechanism is common. A Cochrane review by Jolles and Bogoch[13] concluded that there are no long-term randomized control trials comparing variation of acetabular component positioning with the approach selected for THA. A significant degree of variability exists between various authors when comparing mean angles of anteversion and inclination of acetabular component.[19],[20],[21],[22],[23]

Orthopedic surgeons continue to discuss which surgical approach is best for primary THA, because both of these approaches have merits and demerits. The purpose of this prospective study was to examine the difference between the lateral and posterior approaches with respect to functional outcome, component positioning, intraoperative blood loss, and satisfaction rates.


  Subjects and Methods Top


Study design: The present prospective clinical and radiological comparative study included 82 patients satisfying our inclusion criteria. Patients between the age group of 15–60 years with hip OA secondary to AVN of femur head, for whom THA was planned, were included in our study. Patients with significant comorbidities, history of hip fractures, previous hip surgeries, and spine problems were not taken into the study. Patients operated between January 2018 and January 2019 were taken into the study. Of all THA cases, 82 hips satisfying inclusion criteria were included in the study. Follow-ups were available for 70 patients (21 lateral approach and 49 posterior approach hips). Etiology was sickle cell anemia for 2 patients, lupus for 1 patient, and idiopathic AVN for 67 patients. Study approval was taken from the Institutional Ethics Committee (ethics committee approval number: 663/2018). Informed consent was obtained from all patients prior to inclusion. Preoperative HHS was calculated for all patients.

Surgical technique

THA was performed by a group of senior surgeons in our institute with an experience of more than 15–20 years, who were well versed with both lateral and posterior approaches. Lateral approach was performed with the patient in the supine position and posterior approach with the patient in the lateral position. [Figure 1] shows preoperative radiographs and intraoperative images of THA. Cementless tapered titanium straight stem with hydroxyapatite surface coating (Corail, DePuy), cementless titanium press-fit cup (Pinnacle or Duraloc, Depuy) with or without screws, ceramic or metal head, and polyethylene liner with 10° elevated lip were used in all patients.
Figure 1: Preoperative radiographs (a). Intraoperative images (b and c) of THA, THA: Total hip arthroplasty

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Follow-up and assessment

HHS and radiographic measurements (cup inclination, cup version, and femoral stem tip position) were calculated at 12 months and at the latest follow-ups using low-centered anteroposterior (AP) radiographs of the pelvis and cross-table lateral hip radiographs in both groups. Anteversion angle was calculated using the cup anteversion inclination app (version 3.5) available in the Apple app store and cross-checked with cross-table lateral radiographs [Figure 2] and [Figure 3]. An AP radiograph was uploaded to the app, and the following points are marked with pointers: T1, T2, C3, C4, C5, and C6. Once all the above points are marked, the application calculates the version angle based on long diameter (D1) and short diameter (D2) of the oval formed at the base of the cup [Figure 4]. Generic satisfaction questionnaire[24] was used to measure satisfaction after THA at the latest follow-up.
Figure 2: Radiographic measurements of cup inclination (IA) and cup version (v) angles (posterior approach) using cup inclination app (version 3.5) on anteroposterior (a) and cross-table lateral radiographs (b)

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Figure 3: Radiographic measurements of cup inclination (IA) and cup version (v) angles (lateral approach) using cup anteversion inclination app (version 3.5) on anteroposterior (a) and cross-table lateral (b) radiographs

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Figure 4: Screenshot of cup anteversion inclination app (version 3.5) while calculating inclination and version angles of acetabulum cup, and line diagram showing points to be marked with a pointer (T1: right or left acetabular tear drop, C3: Right most medial point of the cup, C4: Right most lateral point of the cup, C5: Right most caudal point of the cup, C6: Cephalad point of the cup). D1(long diameter) line in blue color and the D2 (short diameter) line in violet color are diameters of oval formed by the base of the cup on AP radiograph, which are utilized by the app to calculate cup version angles

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Statistical analysis

Data were collected using prestructured data forms and analyzed with unpaired Student's t-test with 95% confidence interval.


  Results Top


Functional outcome

Demographic data and preoperative HHS are summarized in [Table 1]. The mean HHS attained at the end of average 3.6 years after surgery in the lateral approach group (LAG) was 88.05 and in the posterior approach group (PAG) was 90.32 with P = 0.178. PAG did marginally better than the LAG, but no significant difference was observed in HHS.
Table 1: Demographic data and mean preoperative Harris Hip score

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Radiological outcome

Average inclination of the cup in the lateral approach was 37.9° (32–51) and in the posterior approach was 45.02° (23–62); P = 0.00027 (Student's t-test). Result was significant at P < 0.05. Hence, the angle of inclination of the acetabular cup was significantly high in the posterior approach compared with the LAG, while both the mean values were in Lewinnek safe zone.[19] The average cup version angle in the lateral approach was 16.14° (4–32) and in the posterior approach was 27.69° (6–48) with P ≤ 0.00001. Cup version angle was significantly more in the posterior approach compared to the lateral approach. In the postoperative AP radiographs, in the LAG, 17 femoral stems were in neutral, and four stems were in the valgus position. In the PAG, 44 femoral stems were in neutral, four stems in valgus, and one stem in varus. No significant variation in femoral component positioning between the two groups. In postoperative sagittal cross-table lateral films of the LAG, stems were aligned with the proximal part anterior and tip directed posterior in 18 hips and proximal and distal parts in the center in 3 hips. In the PAG, stems were aligned with the proximal anterior and tip-directed posterior in 26 hips and the proximal and distal parts in the center in 23 hips. A significant variation in component positioning in the sagittal plane is present. Majority of stems (18 of 21) in the lateral approach have their tips directed posterior, while only half (26 of 49) of the cases in the posterior approach have tips directed toward the posterior cortex of the femur.

The mean blood loss during surgery in the lateral approach was 436.67 ml and in the posterior approach was 510 ml (P = 0.04). There was significantly more blood loss in the posterior approach compared to the lateral approach. Nineteen out of 21 lateral approach patients and 45 out of 49 posterior approach patients are very satisfied/satisfied with their outcomes after THA according to Mahomed et al.'s[24] generic satisfaction scale for joint replacement arthroplasty.

Complications

None of our patients had dislocation, prosthetic joint infection, component loosening, or component subsidence. Two patients in LAG and three patients in PAG had suture abscesses, treated with superficial debridement, daily dressings, and antibiotic support. One patient in the PAG group needed a secondary wound closure. Ten patients in LAG and six patients in PAG had abductor weakness and limp at 3-month follow-up, which were corrected subsequently with abductor strengthening physiotherapy exercises. One patient in the PAG group (sickle cell etiology) was readmitted 3 months after surgery with pulmonary complications and was discharged in a week after an appropriate treatment.


  Discussion Top


In our study, both the treatment groups did not differ by means of age distribution (P = 0.05094), preoperative HHS values (P = 0.1352), and severity of hip arthritis according to Kellgren and Lawrence[25] classification, thus allowing a fair comparison between both the groups. The mean age in our study was 35.9 years for the lateral approach and 40.14 years for the PAG with no significant difference (P = 0.050943) in distribution of age between the two groups. Smaller age group in our study may be attributed to cases with hip arthritis secondary to AVN of the femoral head (which occurs commonly in the 30–40 years age group).

Barber et al.[2] evaluated functional outcomes in a consecutive series of 49 patients. Patients of both lateral and PAG s improved their score to obtain the same mean score of 94 2 years after surgery. A Cochrane review (4 studies and 260 patients) by Jolles and Bogoch[13] concluded that there is no significant difference in HHS attained by patients between lateral and PAGs. Witzleb et al. compared lateral and posterior approaches in 60 patients,[22] and the mean HHS for the LAG was 77, while that for the PAG was 83 at the end of 3 months of surgery, with no significant difference (P = 0.075). In our study, the mean HHS at 1-year follow-up in the lateral group was 87.05 (standard deviation [SD] =8.62) and that of the posterior group was 90.38 (SD = 5.94). Posterior group did marginally well, but the difference is not statistically significant (P = 0.114). Hence, from our study, there was no significant effect of surgical approach on functional outcome of THA.

Lewinnnek et al.[19] proposed safe zones for acetabular component positioning in THA to be 30°–50° of inclination and 5°–25° of anteversion, and found that the majority of dislocated hips are outside this safe zone. A Cochrane review by Jolles and Bogoch[13] concluded that there are no long-term randomized control trials comparing variation of acetabular component positioning with the approach selected for THA. A significant degree of variability between articles was found when comparing the mean angles of anteversion and inclination [Table 2]. None of these studies have mentioned the use of elevated acetabular liners.
Table 2: Comparison of our study with previous studies

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In our study, we achieved the mean acetabular cup inclination of 37.9° in the lateral approach and 45.02° in the PAG. Difference was found to be significant (P = 0.0027). Both the means are within the Lewinnek safe zone. The mean cup version in lateral approach was 16.14° and in the posterior approach was 27.69°, with a significant difference between the two groups (P ≤ 0.0001). This also prevents posterior dislocation, which is more common in the posterior approach compared to the lateral approach owing to weak posterior muscles and soft tissues after surgery. Elevated acetabular liners with 10° lip were used in all our cases, positions of which cannot be assessed in postoperative radiographs. This gives us extra play with acetabular shells without compromising femoral head coverage. Standard deviation of cup inclination was more in the PAG (SD = 12.8) than lateral approach (SD = 9.65). This could be due to positioning problems in the posterior approach (lateral position).

Vaughan et al.[27] compared femoral component positioning (100 hips with 50 in each group) in lateral and posterior approaches, and found there was a significant difference between the two approaches in sagittal stem tip position only (P = 0.01), but not in coronal tip position (P = 0.1).When not in neutral, stems inserted in lateral approach showed a marked deviation toward the posterior cortex. This was not the case with the posterior approach. In our study, femoral stem position was assessed in both coronal plane (in anteroposterior radiographs) and sagittal plane (in lateral radiographs) for stem alignment. A posterior entry point and neutral stem positioning in the sagittal plane and a neutral/valgus stem positioning in the coronal plane are recommended in both lateral and posterior approaches. In the sagittal plane, 18 out of 21 hips in the LAG showed a marked deviation of tip of femoral component toward the posterior cortex with an anterior entry point in the proximal femur; whereas in PAG, 26 out of 49 hips showed deviation of tip of femoral component toward posterior cortex.

None of our cases had dislocation, prosthetic joint infection, component loosening, or component subsidence. These results of our study are not comparable to previous studies as we have excluded patients with other significant comorbidities and conditions, which could be confounding factors for HHS.

Limitations of our study include small sample size, short- to mid-term follow-up, and calculation of cup angles with standard radiographs rather than CT scans. Further long-term randomized control trials with large sample size, inclusion of patient satisfaction, combined anteversion, and spinopelvic parameters are needed to make definitive conclusions.


  Conclusions Top


There was no significant difference in functional outcome at an average of 3 years and 6 months of follow-up between posterior and direct lateral (Hardinge) approaches in THA. Cup anteversion was significantly more in the PAG in our study. With availability of elevated liners, we propose an extended safe zone for cup version up to 30° upper limit for posterior approach cases to compensate for weak posterior musculature and soft tissues in which hips do well, provided the elevated liner is cautiously used and a good muscle balance and soft tissue tension is achieved. To make definitive conclusions, all clinically relevant factors (i.e. mid- to long-term function, patient satisfaction, complication rates, and long-term survival), combined anteversion, and spinopelvic parameters have to be included in the study. Satisfaction rate is excellent with THA regardless of approach. We are of the opinion that surgeons should follow the approach in which they are trained and comfortable with.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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Downing ND, Clark DI, Hutchinson JW, Colclough K, Howard PW. Hip abductor strength following total hip arthroplasty: A prospective comparison of the posterior and lateral approach in 100 patients. Acta Orthop Scand 2001;72:215-20.  Back to cited text no. 18
    
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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]
 
 
    Tables

  [Table 1], [Table 2]



 

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