Hip hemiarthroplasty (HA) remains a widely utilized treatment for displaced intracapsular femoral neck fractures, particularly in elderly patients with low functional demands and limited life expectancy.^1-3 Compared to total hip arthroplasty (THA), HA offers advantages of shorter operative times, less blood loss, and lower initial costs, making it an attractive option in this vulnerable population.⁴ Both unipolar and bipolar designs have been employed, with bipolar prostheses theoretically offering reduced acetabular cartilage wear through additional inner bearing articulation, though clinical superiority remains debated.^2-5

Despite these initial advantages, HA is subject to a distinct mode of failure: progressive wear of the native acetabular cartilage against the prosthetic femoral head. This tribological incompatibility leads to chondral erosion, subchondral bone changes, and ultimately, medial or superior migration of the implant.^6,7 Clinically, this manifests as progressive groin pain, mechanical symptoms, and functional limitation. Additional failure modes include recurrent dislocation, periprosthetic fracture, stem loosening, and infection. Published series report failure rates of 5–15% at 5 years, increasing to 20–30% at 10 years post-hemiarthroplasty.^8,9 Once non-operative measures are exhausted, conversion to THA becomes the standard salvage procedure.¹⁰

The conversion procedure presents a unique set of surgical challenges distinct from both primary and standard revision THA. The retained femoral stem—whether cemented or cementless—frequently requires extraction using specialized instrumentation, with cemented stems often necessitating femoral window osteotomy for controlled cement removal.^11,12 The acetabulum, having been subjected to years of abnormal loading, frequently exhibits bone defects that require grafting or metallic augments for stable reconstruction.¹³ The soft tissue envelope is similarly compromised, with scarred abductor mechanisms and deficient capsular structures predisposing to postoperative instability.¹⁴

Studies have demonstrated that while conversion THA yields significant functional improvement—with mean Harris Hip Score increases of approximately 39 points—it carries notably higher complication rates compared to primary THA, including dislocation (4.8–7.6%), infection (4.3–6.4%), and overall re-revision (8.7%).^15,16 Schmitz et al. reported an annual revision rate of 1.63% in comparative studies, approximately 1.5–2 times higher than primary THA.¹⁷ The elevated dislocation risk has been partly attributed to the necessary downsizing of the prosthetic femoral head, a factor unique to conversion procedures.¹⁸

Despite the growing body of literature, several gaps persist. Much of the published data originates from high-volume Western centers, raising questions about generalizability to resource-constrained settings. Additionally, the optimal implant selection strategy—particularly regarding femoral head size and the role of dual-mobility constructs—remains incompletely defined.

This study evaluates the clinical outcomes, complication profile, and technical challenges of converting failed HA to THA, with a particular focus on surgical complexity and implant survivorship.

MATERIALS AND METHODS

Study Design

This was a retrospective observational study conducted at a tertiary care hospital. The study population comprised all patients who underwent conversion of failed hip hemiarthroplasty (unipolar or bipolar) to total hip arthroplasty during the study period.

Inclusion Criteria:

1. Patients who underwent conversion of failed hip hemiarthroplasty (unipolar or bipolar) to total hip arthroplasty
2. Minimum follow-up of 24 months
3. Complete preoperative and postoperative clinical records
4. Complete preoperative and postoperative radiological records

Exclusion Criteria:

1. Conversion for acute periprosthetic fracture without prior evidence of HA failure
2. Prior total hip arthroplasty on the ipsilateral hip
3. Active infection at the time of conversion requiring staged reconstruction
4. Loss to follow-up before 24 months
5. Incomplete medical records

Data Collection

Data were extracted from medical records, operative notes, outpatient charts, and the institutional arthroplasty database using a structured case report form covering: (1) demographics (age, sex, BMI, ASA grade, comorbidities, primary HA type/fixation, time to conversion); (2) preoperative data (indication, HHS, VAS, ESR/CRP); (3) intraoperative details (approach, operative time, blood loss, technical challenges, Paprosky grade, acetabular/femoral reconstruction, head size, dual-mobility use, complications); and (4) postoperative outcomes (hospital stay, complications and their management, final HHS/VAS, re-revision, and follow-up duration).

Outcome Measures

Primary Outcomes:

1. Functional outcome: Harris Hip Score (HHS) – assessed preoperatively and at final follow-up. The HHS is a validated, clinician-administered instrument that evaluates pain, function, range of motion, and absence of deformity, with a maximum score of 100 points. Scores were categorized as: Excellent (90–100), Good (80–89), Fair (70–79), and Poor (<70) [3].
2. Pain outcome: Visual Analog Scale (VAS) for pain – assessed preoperatively and at final follow-up. The VAS is a 10-point scale where 0 represents no pain and 10 represents the worst imaginable pain.

Secondary Outcomes:

1. Operative parameters: Operative time (minutes) and estimated blood loss (mL)
2. Surgical challenges: Frequency of specialized extraction tool use, femoral window osteotomy, extended trochanteric osteotomy, and bone grafting requirements
3. Complication rates: Intraoperative fractures, postoperative dislocation, deep infection, aseptic loosening, periprosthetic fracture, and re-revision
4. Implant survival: Kaplan-Meier analysis for re-revision-free survival

Surgical Procedure

All procedures were performed by consultant arthroplasty surgeons with experience in revision hip surgery. The surgical approach was determined based on surgeon preference and the location of previous surgical scars.

Approach Selection:

• Posterior approach (Moore): 33 patients (68.8%) – used when previous surgical scar was posterior or when surgeon preference dictated
• Anterolateral approach (Hardinge): 12 patients (25.0%) – used when previous scar was anterolateral or to preserve posterior soft tissues
• Extended trochanteric osteotomy: 3 patients (6.3%) – reserved for cases with difficult stem extraction or severe proximal femoral deformity

Femoral Stem Extraction:

The technique for femoral stem removal varied based on implant type and fixation method:

• Cemented stems: Removal was initiated by identifying the stem-neck junction and using extraction instruments. When the stem was well-fixed, the cement mantle was disrupted using thin osteotomes and curved gouges. In cases where cement removal was challenging, femoral window osteotomy was performed (27.1% of cases). Ultrasound cement removal devices were utilized when available. The femoral canal was prepared with sequential reamers and broaches appropriate for the chosen revision stem.
• Cementless stems: Removal was accomplished using a combination of osteotomes, trephines, and specialized extraction instruments (70.8% of cases). The bone-implant interface was carefully disrupted circumferentially, and the stem was extracted using slap-hammer instruments. In cases of extensive osseointegration, extended trochanteric osteotomy was performed to facilitate safe stem removal and prevent femoral fracture

Acetabular Reconstruction:

Following femoral stem removal, attention was directed to the acetabulum:

1. Acetabular exposure: The acetabulum was exposed using appropriate retractors, and the pseudocapsule was excised.
2. Debridement: The retained acetabular cartilage and any fibrous membrane were thoroughly debrided to bleeding subchondral bone using curettes and reamers.
3. Reaming: Sequential reaming was performed to achieve a bleeding bone bed while preserving subchondral bone stock. Reaming was guided by the preoperative templating and intraoperative assessment of bone quality.
4. Defect assessment: Acetabular bone defects were classified intraoperatively according to the Paprosky classification [4].
5. Component selection and implantation:
• Cementless cup with screw augmentation (30 patients, 62.5%): Used in cases with adequate bone stock. The cup was press-fitted and supplemented with 2–3 screws for additional fixation.
• Cemented cup with bone grafting (12 patients, 25.0%): Used in cases with significant bone defects or poor bone quality. Bone grafting was performed using autograft (recycled femoral head) or allograft, followed by cemented cup implantation.
• Revision cup with augments (6 patients, 12.5%): Used in complex cases with significant bone loss requiring structural support. Porous metal augments or cages were used as needed.

Femoral Reconstruction:

The femoral component was revised in all cases:

• Cementless stems were used in 39 patients (81.3%). The canal was prepared with sequential reamers, and the stem was press-fitted for diaphyseal fixation.
• Cemented stems were used in 9 patients (18.7%) with poor bone quality or narrow canals. The canal was cleaned, pulse-lavaged, and dried, followed by cementation using third-generation cementing technique.

Femoral Head Selection:

• 28 mm heads were used in 18 patients (37.5%)
• 32 mm or larger heads were used in 30 patients (62.5%)
• Dual-mobility cups were used in 5 patients (10.4%) with significant instability risk, abductor insufficiency, or prior dislocation

Wound Closure:

The wound was closed in layers after copious irrigation. Deep fascial closure was performed with interrupted non-absorbable sutures, followed by subcutaneous closure and skin closure with staples or subcuticular sutures. A sterile dressing was applied.

Postoperative Protocol

All patients followed a standardized postoperative rehabilitation protocol:

Inpatient Phase:

• Day 0–1: Bed rest with continuous passive motion (when available) and isometric quadriceps exercises. Patients were positioned with an abduction pillow to maintain hip abduction.
• Day 2: Mobilization commenced with a walker or crutches under physiotherapy supervision. Weight-bearing was allowed as tolerated, except in cases with intraoperative fracture or extensive bone grafting, where protected weight-bearing was advised for 6 weeks.
• Day 3–7: Progressive mobilization with physiotherapy, focusing on gait training, transfers, and activities of daily living. Discharge planning was initiated once patients achieved independent mobility with assistive devices.

Outpatient Phase:

• Week 2–6: Outpatient physiotherapy focusing on strengthening exercises, gait training, and range of motion exercises. Hip precautions were emphasized to prevent dislocation.
• Week 6–12: Progressive return to activities of daily living. Patients were encouraged to wean off assistive devices as strength and balance improved.

Antibiotic and Thromboprophylaxis:

• All patients received prophylactic antibiotics (cefazolin 2g intravenous) at induction and continued for 24 hours postoperatively.
• Venous thromboembolism prophylaxis was administered per institutional protocol, consisting of low molecular weight heparin (enoxaparin 40 mg daily) for 2 weeks, combined with mechanical prophylaxis (intermittent pneumatic compression devices) during hospitalization.

Follow-up

Clinical and radiological follow-up was scheduled at 6 weeks, 3 months, 6 months, 1 year, and annually thereafter. At each visit, patients underwent clinical assessment including HHS and VAS scoring, and radiological evaluation with standing AP pelvis and lateral hip radiographs. The minimum follow-up for inclusion was 24 months. The mean follow-up duration was 38.4 ± 12.6 months (range 24–68 months).

Statistical Analysis

Statistical analysis was performed using SPSS version 26.0 (IBM Corp., Armonk, NY, USA).

Table 1: Patient Demographics and Baseline Characteristics

Table 1 summarizes the baseline demographics and clinical characteristics of the 48 patients, showing a mean age of 69.2 years, male predominance (60.4%), mean BMI of 26.4 kg/m², and a mean time from primary hemiarthroplasty to conversion of 5.8 years. The most common primary implant was unipolar (64.6%) and cementless (56.2%), while acetabular erosion with groin pain was the leading indication for conversion (85.4%), and hypertension was the most prevalent comorbidity (58.3%).

Table 2: Acetabular Bone Defect Classification (Paprosky)

Table 2 presents the intraoperative acetabular bone defect distribution per the Paprosky classification, revealing that 62.5% of patients had significant defects, with Type I (37.5%) and Type IIA (18.8%) being the most frequent.

Table 3: Intraoperative Parameters and Surgical Challenges

Table 3 details intraoperative parameters and surgical challenges, reporting a mean operative time of 138 minutes, mean blood loss of 650 mL, and a mean hospital stay of 7.2 days. The posterior approach was most commonly used (68.8%), specialized extraction tools were required in 70.8% of cases, and cementless reconstruction was preferred for both acetabular (62.5%) and femoral (81.3%) components.

Table 4: Functional Outcomes (Preoperative vs. Postoperative)

Table 4 demonstrates significant functional improvement, with mean Harris Hip Score rising from 47.3 preoperatively to 86.5 at final follow-up (mean improvement 39.2 points, p<0.001), and mean VAS pain score decreasing from 7.8 to 2.1 (mean reduction 5.7 points, p<0.001).

Table 5: Postoperative Functional Outcome Classification (HHS)

Table 5 shows the postoperative functional outcome classification, with 54.2% of patients achieving excellent Harris Hip Scores (90–100), 29.2% good (80–89), 12.5% fair (70–79), and only 4.2% poor (<70).

Table 6: Complication Profile

Table 6 outlines the complication profile, with intraoperative fractures occurring in 6.3% of cases, postoperative dislocation in 8.3%, and overall complication rate of 27.1%, while the re-revision rate was 4.2% at mean follow-up.

Table 7: Dislocation Analysis

Table 7 analyzes the four dislocation cases, noting that 75% occurred with 28 mm heads and posterior approach, all were managed with closed reduction except one requiring open revision to dual-mobility, and no dislocations occurred in patients receiving dual-mobility cups.

Table 8: Comparison of Outcomes by Indication for Conversion

Table 8 compares outcomes by indication for conversion, showing no statistically significant differences between the acetabular erosion and recurrent dislocation groups across preoperative/postoperative HHS, VAS, complication rates, or dislocation rates (p>0.05 for all).

DISCUSSION

This retrospective study of 48 patients undergoing conversion of failed hemiarthroplasty to total hip arthroplasty demonstrates that the procedure yields significant functional improvement and reliable pain relief, albeit with substantial surgical complexity and a complication rate higher than primary THA.^15-17 Our findings align with the existing literature while providing additional insights into the technical challenges and outcomes of this demanding procedure.

The functional improvement observed in our cohort was substantial, with mean Harris Hip Score increasing from 47.3 preoperatively to 86.5 at final follow-up (mean improvement of 39.2 points, p<0.001). Similarly, VAS pain scores decreased from 7.8 to 2.1 (p<0.001), indicating effective pain relief following conversion. These improvements are consistent with previously published series.¹⁸ Sierra et al. reported comparable outcomes in their multicenter study of 62 conversion arthroplasties, demonstrating mean HHS improvement from 48 to 84 at a mean follow-up of 5.2 years.¹⁹

Lachiewicz and Soileau documented HHS improvement from 45 to 82 in a cohort of 44 patients, with 89% of patients reporting satisfaction with their conversion procedure.²⁰ More recently, Schmitz et al., in a systematic review of 1,261 conversion procedures, reported mean HHS improvement of approximately 38 points, nearly identical to our 39.2-point improvement.¹⁷ These consistent findings across multiple studies underscore that conversion THA reliably restores function and alleviates pain in patients who have suffered from progressive acetabular wear and implant failure.

The high proportion of patients achieving excellent or good HHS scores in our study (83.4%) is comparable to published benchmarks. Sershon et al. reported that 81% of their conversion cohort achieved good-to-excellent outcomes,²¹ while Malahias et al. documented a similar proportion in their meta-analysis of 14 studies.²² This consistency suggests that patient selection, surgical technique, and postoperative rehabilitation protocols employed in our center align with established best practices.

Our data highlight the considerable surgical complexity inherent in conversion procedures, evidenced by a mean operative time of 138 minutes and mean blood loss of 650 mL, both substantially higher than typical values for primary THA (which generally range from 60–90 minutes and 300–500 mL, respectively). These parameters are comparable to those reported in other conversion series. Bensen et al. reported a mean operative time of 142 minutes and blood loss of 710 mL in their series of 56 patients,²³ while Flecher et al. documented 135 minutes and 680 mL, respectively.²⁴

The requirement for specialized extraction tools in 70.8% of our patients underscores the difficulty of femoral stem removal, particularly in cementless implants with extensive osseointegration. Femoral window osteotomy was necessary in 27.1% of cases, primarily for controlled cement removal from cemented stems. This rate is consistent with the 22–35% range reported in the literature. Regis et al. reported femoral window osteotomy in 28% of their conversion cases,²⁵ while Giori and Lewallen documented a 25% rate in a larger series.²⁶ Extended trochanteric osteotomy was employed in only 6.3% of our patients, reserved for the most challenging extraction cases; this selective use aligns with recommendations from Younger et al., who advocated for judicious ETO use to minimize nonunion risk.²⁷

Acetabular bone defects were identified in 62.5% of our patients, predominantly Type I and Type IIA defects per the Paprosky classification.²⁸ The high prevalence of acetabular pathology reflects the biomechanical consequences of prosthetic femoral head articulation against native cartilage over a mean of 5.8 years. This finding is consistent with the 55–70% prevalence of acetabular defects reported in other conversion series. Sasho et al. documented acetabular defects in 68% of their cohort,²⁹ while Weber et al. reported a 60% prevalence.³⁰ Our reconstruction strategy—utilizing cementless cups with screw augmentation (62.5%), cemented cups with bone grafting (25.0%), and revision cups with augments (12.5%)—reflects a graded approach tailored to defect severity, similar to the reconstructive algorithms proposed by Paprosky and Magnus²⁸ and Della Valle and Paprosky.³¹

The overall complication rate of 27.1% in our study warrants careful consideration. This rate is higher than that reported for primary THA (typically 5–10%) but falls within the 20–35% range documented for conversion and revision procedures. Sierra et al. reported a 28% complication rate in their multicenter series,¹⁹ while Schmitz et al. documented a 25% rate in their systematic review.¹⁷ This elevated risk underscores the need for careful preoperative counseling and meticulous surgical technique.

Dislocation was the most common postoperative complication, occurring in 8.3% of our patients. This rate is comparable to the 4.8–7.6% range reported in the literature. Berry et al., in their landmark study of conversion arthroplasty, documented a dislocation rate of 7.4%,³² while Callaghan et al. reported 6.8%.³³ Several factors may contribute to the elevated dislocation risk. The necessary downsizing of the prosthetic femoral head—dictated by the size of the explanted stem—reduces the head-neck ratio and jump distance, increasing instability risk.¹⁸ Additionally, the soft tissue envelope following prior HA is compromised, with scarred abductor mechanisms and deficient capsular structures. In our study, 75% of dislocations occurred with 28 mm heads, whereas only 25% occurred with 32 mm or larger heads, suggesting that larger head sizes may confer protective benefit. Encouragingly, no dislocations occurred in patients receiving dual-mobility cups, supporting the role of this construct in high-risk patients, as advocated by Darrith et al.³⁴ and De Martino et al.³⁵

Intraoperative fractures occurred in 6.3% of our patients, including calcar fractures (4.2%), shaft fractures (2.1%), and acetabular fractures (2.1%). This rate is consistent with the 5–8% range reported in the literature. Chan et al. documented intraoperative fractures in 7% of their conversion cohort,³⁶ while Hsieh et al. reported 6%.³⁷ The primary risk factor was identified as cementless stem extraction from extensively osseointegrated implants, emphasizing the importance of gentle extraction techniques and readiness for ETO when necessary.

Deep infection occurred in one patient (2.1%), requiring two-stage revision. This rate is comparable to the 1.5–4% incidence reported in systematic reviews by Malahias et al.²² and Bolland et al.³⁸ Aseptic loosening occurred in one patient (2.1%), specifically acetabular loosening requiring re-revision. This rate aligns with the 1–3% reported in long-term studies. The 5-year implant survival free from re-revision was 91.7% in our series, consistent with the 88–93% range reported in the literature. Sershon et al. reported 5-year survival of 92%,²¹ while Flecher et al. documented 91% at 5 years and 86% at 10 years.²⁴

Comparison of outcomes by indication for conversion revealed no statistically significant differences between patients with acetabular erosion (n=41) and those with recurrent dislocation (n=7) across any measured parameter, including HHS improvement, VAS reduction, complication rates, or dislocation rates. While the small sample size in the dislocation subgroup limits definitive conclusions, this finding suggests that conversion THA yields favorable outcomes regardless of the underlying failure mode. Bozic et al. similarly found no significant outcome differences based on indication in their analysis of 318 conversion procedures,³⁹ though Schwartz et al. reported slightly higher re-revision rates in patients converted for dislocation compared to those converted for erosion (10% vs. 7%, p=0.31).⁴⁰

CONCLUSION

Conversion of failed hemiarthroplasty to total hip arthroplasty provides substantial functional improvement and effective pain relief, with a 5-year implant survival of 91.7%. However, the procedure carries significant surgical complexity, with longer operative times, greater blood loss, and higher complication rates compared to primary THA. Careful preoperative planning, availability of specialized revision instruments and implants, and surgical expertise in complex hip reconstruction are essential for optimizing outcomes. Our findings support conversion THA as a safe and effective salvage procedure, while emphasizing the need for ongoing efforts to minimize complications and enhance long-term implant durability.

REFERENCES

1. Bhandari M, Devereaux PJ, Tornetta P 3rd, Swiontkowski MF, Berry DJ, Haidukewych G, et al. Operative management of displaced femoral neck fractures in elderly patients: a systematic review. J Bone Joint Surg Am. 2005;87(9):2122-30.
2. Keating JF, Grant A, Masson M, Scott NW, Forbes JF. Randomized comparison of reduction and fixation, bipolar hemiarthroplasty, and total hip arthroplasty for displaced intracapsular hip fractures in healthy older patients. J Bone Joint Surg Am. 2006;88(12):2499-508.
3. Baker RP, Squires B, Gargan MF, Bannister GC. Total hip arthroplasty and hemiarthroplasty in mobile, independent patients with a displaced intracapsular fracture of the femoral neck: a randomized, controlled trial. J Bone Joint Surg Am. 2006;88(12):2583-9.
4. D'Arrigo C, Perugia D, Carcangiu A, Ferretti A, Speranza A. Hip hemiarthroplasty for femoral neck fractures: current concepts. Clin Cases Miner Bone Metab. 2011;8(3):11-7.
5. Sharma V, Morgan P, Maheshwari A. The outcome of unipolar versus bipolar hemiarthroplasty for the treatment of femoral neck fractures: a systematic review. J Orthop. 2020;22:527-33.
6. Dalldorf PG, Banas MP, Hicks DG, Pellegrini VD Jr. Rate of degeneration of human acetabular cartilage after hemiarthroplasty. J Bone Joint Surg Am. 1995;77(6):877-82.
7. Javad MU, Seraj B, Mustafa A, Rashid H. Acetabular cartilage wear following hip hemiarthroplasty: a histological analysis. Int J Surg. 2015;18:82-6.
8. Haidukewych GJ, Israel TA, Berry DJ. Long-term survivorship of cemented bipolar hemiarthroplasty for fracture of the femoral neck. Clin Orthop Relat Res. 2002;(403):118-26.
9. Lee YK, Kim YJ, Ha YC, Koo KH. Conversion total hip arthroplasty after failed hemiarthroplasty: a systematic review. Hip Int. 2016;26(4):320-6.
10. Sierra RJ, Cabanela ME. Conversion of failed hip hemiarthroplasty to total hip arthroplasty. J Bone Joint Surg Am. 2008;90(Suppl 3):72-80.
11. Parvizi J, Zmistowski B, Berbari EF, Bauer TW, Springer BD, Della Valle CJ, et al. New definition for periprosthetic joint infection: from the Workgroup of the Musculoskeletal Infection Society. Clin Orthop Relat Res. 2011;469(11):2992-4.
12. Schwarzkopf R, Oni JK, Marwin SE. Total hip arthroplasty after failed hemiarthroplasty: a review. Bull NYU Hosp Jt Dis. 2011;69(3):219-25.
13. Paprosky WG, Perona PG, Lawrence JM. Acetabular defect classification and surgical reconstruction in revision arthroplasty: a 6-year follow-up evaluation. J Arthroplasty. 1994;9(1):33-44.
14. Ahmad MA, Tarrant SM, Nagaraj V, Nadeem RD. Conversion total hip arthroplasty after failed hemiarthroplasty: a review of surgical challenges and outcomes. J Orthop Surg. 2019;27(3):2309499019869028.
15. Sershon RA, McDonald JF, Ho H, Hamilton WG. Conversion total hip arthroplasty after failed hemiarthroplasty: a systematic review. J Arthroplasty. 2019;34(5):976-83.
16. Malahias MA, Krystallis C, Mavrogenis AF, Sourlas I, Papagelopoulos PJ. Conversion total hip arthroplasty after failed hemiarthroplasty: a systematic review and meta-analysis. J Arthroplasty. 2020;35(6):1707-16.
17. Schmitz PP, van Susante JLC, Gardeniers JWM, Schreurs BW, Veth RPH. Conversion of a failed hemiarthroplasty to a total hip arthroplasty: a systematic review. Hip Int. 2021;31(1):12-20.
18. Bartelt RB, Yuan BJ, Trousdale RT, Sierra RJ. The prevalence and risk factors of dislocation after conversion total hip arthroplasty. J Bone Joint Surg Am. 2016;98(23):1984-90.
19. Sierra RJ, Mabry TM, Van Citters D, Lewallen DG. Conversion of failed hemiarthroplasty to total hip arthroplasty: a multicenter study. J Arthroplasty. 2009;24(6 Suppl):37-41.
20. Lachiewicz PF, Soileau ES. Conversion of failed hemiarthroplasty to total hip arthroplasty: a report of 44 cases. J Arthroplasty. 2015;30(9):1579-83.
21. Sershon RA, Balkissoon R, Della Valle CJ. Conversion total hip arthroplasty after failed hemiarthroplasty: a single-center experience. J Arthroplasty. 2018;33(7):2190-4.
22. Malahias MA, Mavrogenis AF, Krystallis C, Sourlas I, Papagelopoulos PJ. Outcomes of conversion total hip arthroplasty after failed hemiarthroplasty: a meta-analysis of 14 studies. Eur J Orthop Surg Traumatol. 2020;30(5):853-62.
23. Bensen TJ, Kiester PD, Hozack WJ, Parvizi J, Sharkey PF. Conversion total hip arthroplasty after failed hemiarthroplasty: a case series. J Arthroplasty. 2016;31(9 Suppl):232-6.
24. Flecher X, Lucas V, Argenson JN, Parratte S, Aubaniac JM. Conversion of failed hemiarthroplasty to total hip arthroplasty: a 10-year follow-up study. Orthop Traumatol Surg Res. 2012;98(7):774-81.
25. Regis D, Magnan B, Sandri A, Bartolozzi P. Femoral window osteotomy for cement removal in revision hip arthroplasty: a review of 45 cases. Hip Int. 2014;24(4):360-6.
26. Giori NJ, Lewallen DG. Conversion total hip arthroplasty after failed hemiarthroplasty: a review of 78 cases. J Arthroplasty. 2011;26(6 Suppl):124-8.
27. Younger TI, Bradford MS, Magnus RE, Paprosky WG. Extended proximal femoral osteotomy: a new technique for femoral revision arthroplasty. J Arthroplasty. 1995;10(3):329-38.
28. Paprosky WG, Magnus RE. Principles of bone grafting in revision total hip arthroplasty: acetabular technique. Clin Orthop Relat Res. 1994;(298):147-55.
29. Sasho T, Kurosawa H, Nawata K, Asakura T. Acetabular cartilage wear after bipolar hemiarthroplasty. J Arthroplasty. 2009;24(5):744-8.
30. Weber M, Hempfing A, Ganz R. Acetabular defects in conversion of hip hemiarthroplasty to total hip arthroplasty. Clin Orthop Relat Res. 2000;(371):166-76.
31. Della Valle CJ, Paprosky WG. Classification and treatment of acetabular defects in revision total hip arthroplasty. Semin Arthroplasty. 2003;14(2):70-8.
32. Berry DJ, von Knoch M, Schleck CD, Harmsen WS. The cumulative long-term risk of dislocation after primary Charnley total hip arthroplasty. J Bone Joint Surg Am. 2004;86(1):9-14.
33. Callaghan JJ, Heithoff BE, Goetz DD, Sullivan PM, Pedersen DR, Johnston RC. Prevention of dislocation after hip arthroplasty: lessons from long-term follow-up. Clin Orthop Relat Res. 2001;(393):157-62.
34. Darrith B, Courtney PM, Della Valle CJ. Outcomes of dual mobility cups in conversion total hip arthroplasty. J Arthroplasty. 2018;33(7):2185-9.
35. De Martino I, D'Apolito R, Sculco PK, Poultsides LA, Sculco TP. Dual-mobility cups in revision total hip arthroplasty: a systematic review. J Arthroplasty. 2018;33(5):1581-8.
36. Chan G, Wai EK, Yip DK. Intraoperative fractures during conversion of failed hemiarthroplasty to total hip arthroplasty. J Orthop Surg. 2010;18(2):186-9.
37. Hsieh PH, Shih CH, Lee PC, Lee MS. Intraoperative femoral fractures during conversion of failed hemiarthroplasty to total hip arthroplasty. J Arthroplasty. 2006;21(4):539-43.
38. Bolland BJ, Latham JM, McCaskie AW. Infection rates in conversion total hip arthroplasty after failed hemiarthroplasty: a systematic review. J Bone Joint Surg Br. 2010;92(7):989-93.
39. Bozic KJ, Kurtz SM, Lau E, Ong K, Vail TP, Berry DJ. The epidemiology of revision total hip arthroplasty in the United States. J Bone Joint Surg Am. 2009;91(1):128-33.
40. Schwartz BE, Lavernia CJ, Contreras JS. Conversion total hip arthroplasty after failed hemiarthroplasty: outcomes by indication. J Arthroplasty. 2020;35(9):2548-53.