Avascular necrosis (AVN), also known as osteonecrosis of the femoral head, is a progressive pathological condition resulting from compromised blood supply to the femoral head, leading to ischemic death of bone cells, structural collapse of the femoral head, secondary degenerative arthritis, and ultimately severe functional disability [1-3]. The disease commonly affects young and middle-aged adults and represents a major cause of hip pain and loss of mobility in this population. Several risk factors have been implicated in the development of AVN, including chronic alcohol consumption, prolonged corticosteroid therapy, trauma, hemoglobinopathies, connective tissue disorders, and metabolic abnormalities [1-3].

The natural history of untreated AVN is characterized by progressive collapse of the subchondral bone and deterioration of the articular surface. In the early stages, joint-preserving procedures such as core decompression, bone grafting, and osteotomies may delay disease progression. However, once femoral head collapse and secondary arthritic changes occur, as seen in Grade IV disease, total hip replacement (THR) becomes the most reliable treatment option for restoring function and alleviating pain [2,3].

Total hip replacement is widely regarded as one of the most successful reconstructive procedures in modern orthopaedics. Since the pioneering low-friction arthroplasty introduced by Charnley, advances in implant design, bearing surfaces, fixation techniques, and perioperative care have resulted in excellent long-term survivorship and patient satisfaction [4,5]. THR has consistently demonstrated significant improvements in pain relief, gait restoration, hip function, and quality of life among patients with advanced hip pathology [4,5].

An important determinant of postoperative outcome in THR is the surgical approach employed. Various approaches have been described, including posterior, direct lateral, anterolateral, and direct anterior approaches. Among these, the posterior and direct lateral approaches remain the most widely practiced because they provide adequate exposure of the acetabulum and proximal femur while facilitating accurate component placement [6-8].

The posterior approach offers excellent visualization of the acetabulum and femur and preserves the abductor musculature, which may facilitate postoperative gait recovery. However, disruption of the posterior capsule and short external rotators has traditionally been associated with an increased risk of postoperative instability and dislocation [6,9]. Contemporary modifications involving meticulous posterior soft-tissue repair have substantially reduced this complication, yet concerns regarding stability continue to influence surgical decision-making [9].

The direct lateral or Hardinge approach preserves posterior stabilizing structures and has historically been associated with lower dislocation rates [10]. Nevertheless, splitting of the gluteus medius and minimus muscles may potentially lead to postoperative abductor weakness, limping, gait disturbances, and superior gluteal nerve injury [10,11]. Consequently, considerable debate remains regarding the superiority of one approach over the other.

Several comparative studies have evaluated functional outcomes and complications associated with different THR approaches. Jolles and Bogoch reported no major difference in long-term outcomes between posterior and lateral approaches [12]. Witzleb et al. similarly demonstrated comparable short-term recovery following both procedures [13]. Rosenlund et al. observed equivalent patient-reported outcomes after THR regardless of surgical approach [14]. Castioni et al. further reported comparable improvements in functionality and quality of life among patients treated through posterior and lateral approaches [15]. In contrast, Skoogh et al. reported higher reoperation rates due to dislocation following the posterior approach, highlighting the continuing controversy surrounding approach selection [16].

Patients with AVN differ from those undergoing arthroplasty for primary osteoarthritis because they are often younger, more active, and have greater long-term functional demands. Therefore, optimization of postoperative function while minimizing complications is of particular importance in this population [1-3]. Comparative evaluation of the posterior and lateral approaches may help surgeons select the most appropriate surgical technique and provide evidence-based recommendations for clinical practice.

Therefore, the present study was undertaken to compare the functional outcomes and complication rates of total hip replacement performed through posterior and direct lateral approaches in patients with Grade IV avascular necrosis of the hip.

This prospective comparative study was conducted in the Department of Orthopaedics, Pt. Jawahar Lal Nehru Memorial Medical College and Dr. B.R.A.M. Hospital, Raipur, Chhattisgarh, India. Institutional Ethics Committee approval was obtained before commencement of the study, and written informed consent was obtained from all participants.

 Study Population

Patients presenting with Grade IV avascular necrosis of the hip and planned for primary total hip replacement were considered eligible for inclusion.

 Inclusion Criteria

• Age greater than 18 years
• Radiologically confirmed Grade IV AVN of the hip
• Willingness to undergo surgery and participate in follow-up

 Exclusion Criteria

• Active infection
• Neurological disorders affecting gait
• Severe systemic illness affecting mobility
• Non-compliant patients

 Study Groups

A total of 48 patients were included in the study and were allocated according to the surgical approach used:

• Group A (Posterior Approach): 26 patients
• Group B (Direct Lateral Approach): 22 patients

All procedures were performed by experienced orthopaedic surgeons under standard aseptic precautions using contemporary THR techniques.

 Preoperative Assessment

All patients underwent detailed clinical examination, radiographic evaluation, routine laboratory investigations, and baseline functional assessment. Harris Hip Score (HHS) was recorded preoperatively for every participant.

 Postoperative Management

Standard postoperative care was provided, including antibiotics, analgesics, thromboprophylaxis, physiotherapy, and early mobilization. Patients were encouraged to commence rehabilitation according to institutional protocols. Hip precautions were explained and reinforced during follow-up visits.

Follow-up and Outcome Assessment

Patients were evaluated at:

• 3 weeks
• 6 weeks
• 3 months
• 6 months

The primary outcome measure was functional outcome assessed using the Harris Hip Score (HHS). Secondary outcomes included postoperative complications such as:

• Limp
• Limb length discrepancy (LLD)
• Dislocation
• Infection
• Other procedure-related complications

 Statistical Analysis

Data were entered into Microsoft Excel and analyzed using SPSS version 20.0. Continuous variables were expressed as mean ± standard deviation, whereas categorical variables were presented as frequencies and percentages. Independent t-tests were used for comparison of continuous variables between groups, and Chi-square tests were applied for categorical variables. Paired t-tests were utilized to assess changes in HHS during follow-up within each group. A p-value <0.05 was considered statistically significant.

A total of 48 patients with Grade IV avascular necrosis of the hip underwent total hip replacement during the study period. Twenty-two patients were operated using the direct lateral approach and twenty-six patients underwent surgery using the posterior approach. Both groups were comparable with respect to demographic characteristics, disease profile, and baseline functional status, thereby allowing a meaningful comparison of postoperative outcomes.

Table 1. Baseline Demographic and Clinical Characteristics of the Study Population

Figure 1. Baseline demographic profile of study participants.

The majority of patients were males (81.3%), reflecting the known epidemiology of AVN. Right-sided hip involvement was slightly more common than left-sided disease (56.3% vs. 43.8%). Most patients had no associated co-morbidity (70.8%), while hypertension was the commonest associated medical condition. No statistically significant differences were observed between the two study groups.

Table 2. Etiological Distribution of Grade IV AVN

Figure 2. Etiological distribution of avascular necrosis in both groups.

Alcohol-related AVN constituted the largest etiological category and accounted for nearly half of all cases (43.8%). Idiopathic and sickling-related AVN each contributed 22.9% of cases, whereas steroid-induced disease represented only 10.4% of the study population. Alcohol-related disease predominated in both surgical groups.

Table 3. Comparison of Harris Hip Scores Between Groups During Follow-up

Figure 3. Mean Harris Hip Score progression during follow-up.

Both approaches demonstrated marked improvement in functional status after surgery. Baseline HHS scores were comparable between groups. Although no significant differences were observed at 3 weeks and 6 weeks, the lateral approach demonstrated significantly higher HHS values at 3 months (p=0.014). At the final six-month assessment, both groups achieved excellent functional recovery, and the difference was no longer statistically significant.

Table 4. Final Functional Outcome According to Harris Hip Score Grade

Figure 4. Distribution of final HHS grades in both groups.

At six months, excellent outcomes were achieved in 59.6% of patients, while an additional 31.9% achieved good outcomes. Only four patients demonstrated fair or poor outcomes. Although excellent results were numerically more frequent in the lateral approach group, the difference between groups did not reach statistical significance.

Table 5. Postoperative Functional Parameters: Limp and Range of Motion

Figure 5. Comparison of postoperative limp and ROM scores.

Most patients demonstrated satisfactory gait recovery and preserved hip mobility at final follow-up. Absence of limp was documented in 59.6% of patients, while 89.4% achieved the maximum ROM score of 5. No statistically significant difference was observed between the surgical approaches for either parameter.

Table 6. Limb Length Discrepancy and Dislocation

Figure 6. Comparison of LLD and dislocation rates.

Limb length discrepancy was observed in 39.6% of patients and occurred with similar frequency in both groups. Hip dislocation occurred in only two patients overall, one in each surgical group. Statistical analysis demonstrated no significant association between surgical approach and either complication.

Table 7. Infection and Other Complications

Figure 7. Distribution of postoperative complications.

Postoperative complications were uncommon. Only one patient developed superficial wound infection, which responded to debridement and antibiotic therapy. Protrusio acetabuli occurred in three posterior-approach cases. Neither complication demonstrated a statistically significant association with the surgical approach employed

Table 8. Improvement in Harris Hip Score from Baseline to Six Months

Figure 8. Mean gain in Harris Hip Score after THR.

Within-group analysis demonstrated highly significant improvement in HHS at every follow-up interval in both cohorts (all p<0.001). Patients undergoing the lateral approach experienced a mean HHS gain of 61.52 points, while those undergoing the posterior approach demonstrated an improvement of 57.42 points. These findings confirm substantial functional recovery irrespective of the surgical approach utilized.

Overall Summary of Results

The study demonstrated that both posterior and lateral approaches for total hip replacement in Grade IV AVN of the hip provide excellent functional recovery with low complication rates. The lateral approach showed a statistically significant advantage at the 3-month follow-up; however, this benefit was not sustained at six months. Final HHS grades, postoperative mobility, dislocation rates, infection rates, and overall complication profiles were comparable between groups, indicating that both approaches are safe and effective options for managing advanced AVN of the hip.

The present study compared the functional outcomes and complication rates of total hip replacement performed through direct lateral and posterior approaches in patients with Grade IV avascular necrosis of the hip. The findings demonstrated significant postoperative improvement in both groups, with excellent functional recovery and low complication rates. Although the lateral approach showed superior functional scores at the three-month follow-up, both approaches achieved comparable outcomes at six months.

The mean age of patients included in the present study was 40.73 years, with no statistically significant difference between the two groups. Most patients belonged to the third and fourth decades of life, reflecting the well-established epidemiology of AVN. Mont et al. reported that osteonecrosis predominantly affects young and middle-aged adults and frequently results in severe disability during their most productive years [2]. Similar age distributions have been reported by Barati et al. and Patel et al. in studies evaluating THR outcomes among patients with AVN [17,18].

Male predominance was observed in the present study, with males accounting for more than four-fifths of all cases. This finding is consistent with previous literature indicating a higher incidence of AVN among men, largely attributable to greater exposure to risk factors such as alcohol consumption and trauma [19,20]. Alcohol-related AVN was the most common etiology in the present study, accounting for 43.8% of cases, which further supports these observations.

A major finding of the present study was the substantial improvement in Harris Hip Scores following surgery. Patients treated through the lateral approach improved from a mean preoperative HHS of 31.00 to 92.52 at six months, whereas patients undergoing the posterior approach improved from 31.27 to 88.69 during the same period. These results demonstrate the effectiveness of THR in restoring hip function in advanced AVN. Similar findings have been reported by Rosenlund et al., Castioni et al., and Restrepo et al., who documented marked postoperative improvements in function and quality of life following THR regardless of surgical approach [14,15,21].

Although baseline and early postoperative HHS scores were comparable between groups, the lateral approach demonstrated significantly higher scores at three months postoperatively. This finding suggests that the lateral approach may facilitate more rapid intermediate recovery. Comparable observations have been reported by Upadhyay and Kumar et al., who described improved early gait recovery and functional performance among patients undergoing non-posterior approaches [22,23]. Preservation of posterior soft-tissue stabilizers may contribute to increased patient confidence and accelerated rehabilitation during the early postoperative period.

Despite the observed difference at three months, the advantage was not maintained at six months. Both groups achieved excellent final HHS values, and the difference between approaches was no longer statistically significant. These findings are in agreement with the observations of Jolles and Bogoch, Witzleb et al., Berstock et al., and Khan et al., who concluded that long-term outcomes after THR are largely independent of surgical approach when modern operative techniques are employed [12,13,24,25].

Evaluation of final HHS grades further supports this conclusion. Excellent outcomes were achieved in nearly 60% of patients, while more than 90% attained good-to-excellent functional results. Although the lateral group demonstrated a slightly higher proportion of excellent outcomes, the difference was not statistically significant. Similar results have been reported by Patel et al. and Reddy et al., who observed comparable long-term functional recovery following both approaches [18,26].

The assessment of postoperative gait and hip mobility revealed favorable outcomes in both groups. Most patients were free of residual limp, and nearly 90% achieved the maximum ROM score. Historically, concerns have been raised regarding potential abductor weakness following the lateral approach because of gluteal muscle splitting [10]. However, the present findings suggest that modern surgical techniques and meticulous soft-tissue handling effectively minimize this complication. Comparable observations have been reported by Gwynne-Jones et al., who found no clinically meaningful long-term differences in gait outcomes between surgical approaches [27].

Complication rates in the present study were low. Limb length discrepancy occurred in approximately 40% of patients, but the incidence was comparable between groups and did not significantly influence functional outcomes. Similar findings have been reported by Petis et al. and Sheth et al., who emphasized that minor discrepancies may occur despite careful surgical planning and are frequently clinically insignificant [6,28].

Postoperative dislocation occurred in only two patients, one in each group. The overall dislocation rate of 4.2% compares favorably with previous reports. Skoogh et al. observed higher revision rates related to dislocation following posterior THR; however, advances in capsular repair techniques have substantially reduced this risk in contemporary practice [16]. Chen et al. highlighted the importance of meticulous posterior capsular closure in maintaining postoperative stability and reducing dislocation rates [29].

Only one patient developed superficial wound infection, which resolved with debridement and antibiotic therapy. No deep infections or revision procedures were required. The low infection rate observed in this study reflects adherence to standard perioperative infection prevention measures and is consistent with previously published reports [30].

Protrusio acetabuli occurred in three patients in the posterior group; however, the association was not statistically significant. This complication is more likely related to acetabular preparation, bone quality, and surgical technique rather than the choice of surgical approach itself [6,24].

Overall, the findings of the present study indicate that both posterior and direct lateral approaches provide excellent functional outcomes and acceptable safety profiles in patients undergoing THR for Grade IV AVN. Although the lateral approach demonstrated a temporary advantage during intermediate recovery, both approaches achieved comparable final outcomes. Consequently, surgical approach selection should be individualized according to surgeon experience, technical familiarity, and patient-specific considerations rather than expectations of substantial differences in long-term results.

Total hip replacement provides excellent functional recovery in patients with Grade IV avascular necrosis of the hip. Both direct lateral and posterior approaches resulted in substantial improvement in Harris Hip Scores and achieved favorable clinical outcomes with low complication rates. The lateral approach demonstrated a significant functional advantage at three months; however, this difference was not maintained at six months. Final functional outcomes, range of motion, gait recovery, and complication rates were comparable between groups. Therefore, both approaches can be considered safe and effective options for total hip replacement in advanced AVN of the hip, and the choice of approach should be individualized according to surgeon preference, technical expertise, and patient characteristics.

1. Ficat RP. Idiopathic bone necrosis of the femoral head. J Bone Joint Surg Br. 1985;67(1):3-9.
2. Mont MA, Cherian JJ, Sierra RJ, Jones LC, Lieberman JR. Osteonecrosis of the femoral head. J Bone Joint Surg Am. 2015;97(18):1604-27.
3. Mont MA, Hungerford DS. Nontraumatic avascular necrosis of the femoral head. J Bone Joint Surg Am. 1995;77:459-74.
4. Charnley J. Low friction arthroplasty of the hip. Berlin: Springer; 1979.
5. Learmonth ID, Young C, Rorabeck C. The operation of the century: total hip replacement. Lancet. 2007;370(9597):1508-19.
6. Petis S, Howard JL, Lanting BL, Vasarhelyi EM. Surgical approach in primary total hip arthroplasty: anatomy, technique and clinical outcomes. Can J Surg. 2015;58(2):128-39.
7. Higgins BT, Barlow DR, Heagerty NE, Lin TJ. Anterior vs posterior and lateral approaches in total hip arthroplasty. Orthopedics. 2015;38(2):e120-7.
8. Ang JJM, Onggo JR, Stokes CM, Ambikaipalan A. Comparing direct anterior approach versus posterior or lateral approach in total hip arthroplasty: a systematic review and meta-analysis. Eur J Orthop Surg Traumatol. 2023;33(7):2773-92.
9. Masonis JL, Bourne RB. Surgical approach, abductor function, and total hip arthroplasty dislocation. Clin Orthop Relat Res. 2002;(405):46-53.
10. Hardinge K. The direct lateral approach to the hip. J Bone Joint Surg Br. 1982;64(1):17-9.
11. Khan RJ, MacDowell A, Crossman P, Keene GS. The effect of surgical approach on outcomes of total hip arthroplasty: a systematic review. J Arthroplasty. 2006;21(6):847-54.
12. Jolles BM, Bogoch ER. Posterior versus lateral surgical approach for total hip arthroplasty in adults with osteoarthritis. Cochrane Database Syst Rev. 2004;(1):CD003828.
13. Witzleb WC, Stephan L, Krummenauer F, Neuke A, Gunter KP. Short-term outcome after posterior versus lateral surgical approach for total hip arthroplasty: a randomized clinical trial. Eur J Med Res. 2009;14(6):256-63.
14. Rosenlund S, Broeng L, Holsgaard-Larsen A, Jensen C, Overgaard S. Patient-reported outcome after total hip arthroplasty: comparison between lateral and posterior approach. Acta Orthop. 2017;88(3):239-47.
15. Castioni D, Galasso O, Iannò B, Mercurio M, Gasparini G. Posterior versus lateral surgical approach: functionality and quality of life after total hip arthroplasty in a matched cohort study. BMC Musculoskelet Disord. 2021;22(Suppl 2):932.
16. Skoogh O, Tsikandylakis G, Mohaddes M, Nemes S, Odin D, Grant P, et al. Posterior surgical approach in total hip replacement: still more reoperations due to dislocation compared with direct lateral approach? Acta Orthop. 2019;90(5):411-6.
17. Barati AZ, Lei S, Qi FX, Peng ZJ, Barati SUDD, Adhikari S. Comparison of posterolateral and lateral approach for total hip replacement in avascular necrosis of femoral head: a retrospective study of 46 cases. Int J Adv Res. 2019;7(4):837-43.
18. Patel M, Sidhdhapuria P, Menon H, Chaudhari N. Comparison of functional outcomes of hip arthroplasty via posterior and lateral approach. Int J Orthop Sci. 2019;5(3):278-84.
19. Aaron RK, Ciombor DM. Osteonecrosis of the femoral head. J Am Acad Orthop Surg. 1996;4:231-7.
20. Mankin HJ. Nontraumatic necrosis of bone. N Engl J Med. 1992;326:1473-9.
21. Restrepo C, Parvizi J, Pour AE, Hozack WJ. Prospective randomized study of two surgical approaches for total hip arthroplasty. J Arthroplasty. 2010;25(5):671-9.
22. Upadhyay SS. Early functional outcome and gait comparison between lateral and posterior approaches in THA. Paripex Indian J Res. 2024;13(10).
23. Kumar A, Nama KG, Meena RP, Rawat SS. Functional recovery in avascular necrosis hip following THA: anterior vs posterior approach in Indian population. Int J Res Orthop. 2024.
24. Berstock JR, Blom AW, Beswick AD. A systematic review and meta-analysis of surgical approaches in total hip arthroplasty. Hip Int. 2015;25(1):8-17.
25. Khan RJ, MacDowell A, Crossman P, Keene GS. The effect of surgical approach on outcomes of total hip arthroplasty: a systematic review. J Arthroplasty. 2006;21(6):847-54.
26. Reddy KJ, Rao SK, Prasad R. Functional outcome of THA using posterolateral versus lateral approach. Indian J Orthop Surg. 2019;5(3):210-4.
27. Gwynne-Jones DP, Garneti N, Muirhead-Allwood SK. Surgical approach and early complications after total hip arthroplasty. Hip Int. 2018;28(2):140-6.
28. Sheth D, Cafri G, Inacio MCS, Paxton EW, Namba RS. Anterior and anterolateral approaches compared with posterior approach in total hip arthroplasty. J Bone Joint Surg Am. 2015;97(17):1401-8.
29. Chen R, Jin Y, Chen L, Chen P, Lyu S, Tong P, et al. Surgical technique: a simple technique for closing the capsule of the hip in posterolateral approach total hip arthroplasty. BMC Musculoskelet Disord. 2025;26(1):207.
30. Gupta L, Lal M, Aggarwal V, Rathor LP. Surgical technique of total hip arthroplasty: experience from a tertiary hospital in India. Int J Res Orthop. 2018.