Total hip arthroplasty (THA) is nowadays a frequent surgery in orthopedic practice surgery [1] [2] . The damaged joint replacement improves the patient’s life quality. It suppresses pain and restores almost normal hip mobility [1] . Surgical technique and instrumentation have improved since Charnley [3] [4] . Advances made it possible to extend the indications for THA to previously considered difficult cases, and therefore ineligible for arthroplasty [5] . A complex hip condition is a hip with unusual bone and/or soft tissue disorder. It includes displastic hip, ankylosed hip, protrusio acetabuli, fractures about the hip, and some neuromuscular conditions [1] [2] [5] [6] . We added neglected hip dislocations and advanced hip necrosis in hemoglobinopathies patients. THA in these cases remains a challenge and requires good preoperative planning. It is often necessary to have custom implants or modular implants [5] [6] . In a low-resource setting, bringing together the technical logistical conditions conducive to this surgery is an additional difficulty.

This work aims are to: 1) determine the spectrum of conditions with difficult primary THA, 2) assess surgical strategies and 3) evaluate the outcome of our cases series.

This was a retrospective study that concerned patients operated on for total hip arthroplasty between January 2015 and December 2022 at the medical center “La Grâce” in Bobo-Dioulasso, Burkina Faso.

Patients with coxarthrosis (on hip dysplasia, acetabular protrusio, acetabular malunion or neurological hip) and those with ankylosis of the hip, osteonecrosis secondary to neglected dislocation of the hip or hemoglobinopathy with obstruction of the femoral canal were included. THA revisions were not included.

We collected information’s from clinical files concerning age, sex, THA indications, operative planning and technique and post-operative evolution.

Pre-operative Planning: We used standard anteroposterior (AP) pelvic X-rays with 100% magnification. Hip dysplasia was assessed through coxometry. Acetabular dysplasia was described according to the Crowe classification [7] . The ilio-ischiatic line evaluated acetabuli protrusio. We graded protrusio minor (less than 3 mm overhanging), moderate or coxa profunda (between 3 and 5 mm overhanging), and major (more than 5 mm overhanging). CT scans weren’t always available for all patients.

A total of 31 total hip replacements were performed in 30 patients. The mean age of patients at the surgery time was 36.2 years with extremes of 17 and 61 years. The male-to-female sex ratio was 1.

THA surgery has become a routine procedure that can be challenging in low-resource settings [8] - [10] . Difficulties stretched from preoperative conditions, perioperative anesthesia, and surgical issues to postoperative rehabilitation. For example, spinal stiffness in ankylosing spondylitis is challenging for anesthesia positioning and rehabilitation [11] . Procedure planning and effective surgical anesthesia and pain control during the rehabilitation ensure a better functional outcome [1] [5] .

In this study, the indications for THA were mainly made up of coxarthrosis secondary to hip dysplasia and aseptic osteonecrosis of neglected hip dislocation. In acetabular dysplasia, the challenge is to cover the cup anteriorly and superiorly [2] [12] . Cup coverage and proper positioning are the keys to its survival. To achieve these two objectives, Dunn and Hess proposed medialization of the cup positioned deep beyond the acetabular base, before performing a bone autograft for optimal coverage [13] . This technique guaranteed an acetabular cup survival rate of 100% at four years and 93.2% at 10 years [13] . According to Chougle et al., the rate of loosening of the acetabular cup is proportional to the severity of the dysplasia [12] . We used the technique of Dunn and Hess [13] to have a deep cup but without going beyond the bottom. The structured bone graft was harvested from the femoral head screwed anteriorly and superiorly. Correct reaming resulted in an acetabular cup bed with uniform continuity ( Figure 1 ). After 45 months, we had a cup survival rate of 100% for all dysplastic acetabula.

An acetabular protrusio is a form of central acetabular dysplasia resulting from the migration of the femoral head beyond the Kohler’s line [14] . This acetabular bone deficiency requires reconstruction of the acetabular bottom. It can be done with fragmented bone grafts harvested from the femoral head. This reconstruction prevents medialization of the hip rotation center [15] [16] . The hip rotation center restoration is important in cup survival [17] [18] . Baghdadi demonstrated that there is a 24% risk of acetabular cup revision in patients with a 1 mm medial or lateral difference between the native hip center and the prosthetic head center [16] [18] [19] . After grafting, an uncemented cup can be impacted. If the bone quality is not sufficient, it is preferable to choose a cemented cup alone or with a metal reinforcement plate [14] . A failure to assess bone quality can lead to early migration of the acetabular cup [20] [21] . After 29 months of mean follow-up time, no cup migration was observed in acetabular protrusio.

THA in hip ankylosis was mainly driven by the patient’s desire to recover from certain functional activities (driving, work, etc.). Loss of hip mobility also leads to soft-tissue retractions [22] . The ideal approach gives large access to the femoral neck and allows the femoral neck osteotomy and location of the paleo-acetabulum [22] . Posterolateral, direct anterior, and lateral approaches with trochanterotomy are discussed [22] [23] . Some authors recommend the use of fluoroscopy [1] [5] .

In low-resource settings, chronic trauma injuries are common especially neglected hip dislocations [24] - [26] . THR in neglected hip dislocations has two main issues: the paleo-acetabulum access and the muscular retractions. The paleo-acetabulum is filled with vascularized fibrous tissues and muscular retractions prevent hip relocation. Some authors suggest primary skeletal bone traction in these cases with fair results [27] [28] . We prefer large muscular release and the help of an iliofemoral distractor to achieve prosthetic hip reduction.

The large spectrum of challenges in complex hip management requires effective preoperative planning. Also, the lack of custom-made implants and acetabular reconstruction solutions in our daily practice might be kept in mind to find safe and effective alternatives. Preoperative planning minimizes complications and ensures a better outcome.