Clinical outcomes of conversion total hip replacements from previous hip fracture operations in the older population

Abstract

Background

Conversion total hip arthroplasty (THA) is a procedure performed to often address complications from previous hip surgery. The objective was (i) to compare primary THA with conversion THA, and (ii) to evaluate the clinical outcomes and complications of different types of conversion THA.

Methods

This was a retrospective study that included primary and conversion THA operated from 2020 to 2024, aged ≥50 years. Operative time, intraoperative blood loss, post-operative functional status, complication and mortality were evaluated.

Results

A total of 107 THA (51 conversion THA, 56 primary THA) in Chinese patients were evaluated. Patients with conversion THA were significantly older than primary THA. Comparing with primary THA, the conversion THA group had worse function. Mean operative time for conversion THA from hip screws was significantly shorter compared to conversion from other implants.

Conclusion

With proper patient counselling and patient selection, conversion THA is a treatment option for complications arising from previous hip fracture surgery.

Keywords

Conversion THA cephalomedullary nail hemiarthroplasty hip screws primary THA

Introduction

The ageing population is an important issue worldwide, with a huge socioeconomic impact on the healthcare system. Osteoporosis affects one in three women and one in five men over the age of 50 and is a prevalent disease that increases the risk of fragility fractures.¹ An osteoporotic or fragility fracture occurs in the setting of low-energy trauma after a fall from standing height or less and is associated with increased mortality rates. One of the most common and serious forms of fragility fractures is the hip fracture, which can cause high rates of mortality within one year, reaching 36%.² There are also challenges posed in the operation for these patients as bone quality is often poor with the addition of multiple medical co-morbidities, which frequently warrants a multidisciplinary approach.³ Over the years, fracture liaison services with orthogeriatric co-care have been established to better manage these patients and to prevent secondary fractures occurring due to high imminent risk of fractures as well.⁴

The mainstay of treatment for elderly patients with un-displaced neck of femur fractures and intertrochanteric fractures is internal fixation due to the lower risk of avascular necrosis.² For displaced neck of femur fractures, the treatment is typically cemented hemiarthroplasty due to the higher risk of avascular necrosis.⁵ With the increasing number of operations performed due to the ageing population, it is expected that complications would also arise. Surgical complications that occur after hip fracture surgery include fixation failure, avascular necrosis, acetabular erosion and non-union. In fact, previous studies have shown that reoperation rates within 24 months were more than 20% in hip fractures with fixation.⁶ Furthermore, age is a significant risk factor for acetabular wear after hemiarthroplasty in elderly patients.⁷ Therefore, revision operations may be required to further treat these patients should surgical complications arise.

Conversion total hip arthroplasty (THA) is an established surgical procedure for treatment of previous hip fracture complications, but it is classically known to be a technically demanding procedure with considerable blood loss, lengthy operation time and complications.⁸ Hong Kong is a city with one of the longest life expectancies worldwide,⁹ and in existing literature, there are few studies focusing on Chinese patients. Therefore, in this study we aim to (i) compare primary THA with conversion THA, and (ii) evaluate the clinical outcomes and complications of different types of conversion THA.

Material and methods

This was a retrospective study that included primary and conversion THA at the Prince of Wales Hospital, Hospital Authority, Hong Kong, China from 2020 to 2024 in a team, aged 50 years or above. This study was approved by the Joint Chinese University of Hong Kong – New Territories East Cluster Clinical Research Ethics Committee (CRE Ref No.: 2024.345). Due to its respective nature, formal consent was not required. The exclusion criteria were patients with THA performed following joint infection, pathological fracture due to bone tumor and previous acetabular fixation. All THAs were performed using the standard posterior approach with the patient in a lateral position. Cemented or uncemented prosthesis was used based on the bone quality of the patient. Uncemented prosthesis was used for patients with satisfactory bone quality (e.g., Dorr A/B femoral bone). Cemented prosthesis was used for patients with Dorr C femoral bone in view of a higher risk of periprosthetic fracture if an uncemented prosthesis was used.¹⁰ Perioperative standard antibiotic prophylaxis with first-generation cephalosporin and mechanical thromboembolism prophylaxis was given to all patients. Data from all our operation records is recorded into the Clinical Management System (CMS) database prospectively.¹¹ For nomenclature, conversion THA is a term for THA performed following previous hip surgery. Primary THA refers to THA performed without previous hip surgery. The indication of THA for all cases was documented.

Data was collected from the CMS on patient demographics, including age, sex, body mass index (BMI), American Society of Anesthesiologist (ASA) class, age-adjusted Charlson Comorbidity Index (ACCI) and drug history. The indication for operation, operative details including operative time, implant choice and intraoperative blood loss was also retrieved. For conversion THA, the details of the previous operation were also retrieved. To evaluate the clinical outcomes and complications of conversion THA, the operative details, functional status after operation and mortality were evaluated. To compare conversion THA with primary THA, clinical outcomes and complications in the two groups were compared. Comparison amongst different types of conversion THA was also evaluated.

All statistical analyses were conducted using IBM SPSS Statistics, version 29 (SPSS Inc., Chicago, IL, USA), with a p < 0.05 considered to be statistically significant. Continuous variables were reported as mean ± standard deviation, while categorical variables were presented as frequency (percentage). Prior to conducting any statistical tests, assumptions were checked to ensure validity. The Shapiro–Wilk test was used to assess normality for continuous variables. For the comparison of continuous variables between two independent groups, an independent t-test or the Mann–Whitney U test was applied. For analyses involving three or more groups, either a one-way analysis of variance or a Kruskal–Wallis test was performed, depending on whether test assumptions were met. Bonferroni-adjusted post-hoc tests were conducted if significant differences were detected to determine which groups differed significantly. Categorical variables were analyzed using either a Chi-square test or Fisher's exact test, and column proportions tests with Bonferroni corrections were performed as pairwise comparison tests to examine group differences.

Results

Patient demographics

A total of 107 (n = 107) THA in Chinese patients were evaluated, where 51 were conversion THA (n = 51) and 56 were primary THA (n = 56). The mean follow-up time for conversion THA was 2.05 ± 1.3 years (747 ± 478 days) and the mean follow-up time for primary THA was 2.10 ± 1.1 years (768 ± 392 days), which was not significantly different. There were no significant differences in sex, BMI, ASA class, ACCI and usage of antiplatelet or anticoagulation drugs between the conversion THA group and primary THA group. The mean age of patients with conversion THA was 79 years old (79.2 ± 8.9), and the mean age of patients with primary THA was 70 years old (70.4 ± 9.2), which was significantly different (p < 0.001) (Table 1). The mean operative time was generally longer and the mean blood loss was generally higher for conversion THA compared to primary THA, but there were no statistically significant differences in blood loss and operative time between the two groups (Table 2).

Table 1.

Demographic characteristics for conversion THA and primary THA patients.

	Conversion THA (N = 51)	Primary THA (N = 56)	p value
Age at THA (year)	79.2 ± 8.9 (59–94)	70.4 ± 9.2 (59–92)	<0.001
Sex			0.155
Male	40 (78.4)	37 (66.1)
Female	11 (21.6)	19 (33.9)
BMI	22.5 ± 3.6 (14.5–29.7)	23.3 ± 4.1 (14.8–31.8)	0.285
Smoking	0 (0)	7 (12.5)	0.013
Alcohol drinking	1 (2)	7 (12.5)	0.062
Usage of aspirin/ anticoagulant			0.074
Use of aspirin	12 (23.5)	7 (12.5)
Use of anticoagulant	7 (13.7)	3 (5.4)
Myocardial infarction	4 (7.8)	0 (0)	0.056
Congestive heart failure	3 (5.9)	3 (5.4)	1.000
Peripheral vascular disease	0 (0)	1 (1.8)	1.000
Stroke or TIA	4 (7.8)	8 (14.3)	0.292
Dementia	5 (9.8)	1 (1.8)	0.101
Liver cirrhosis	1 (2.0)	0 (0)	0.477
Diabetes	7 (13.7)	12 (21.4)	0.298
Chronic kidney disease	3 (5.9)	5 (8.9)	0.718
Malignancy	3 (5.9)	5 (8.9)	0.547
Charlson Comorbidities Index	4 (2–8)	3 (1–8)	0.005
ASA physical score			0.147
1	0 (0)	2 (3.6)
2	21 (41.2)	29 (52.7)
3	29 (56.9)	24 (43.6)
4	1 (2)	0 (0)
Follow-up (years)	2.05 ± 1.3	2.10 ± 1.1	0.789

Data expressed as mean ± SD (range) or frequency (percentage). THA: total hip arthroplasty; BMI: body mass index; TIA: transient ischemic attack; ASA: The American Society of Anesthesiologists; SD: standard deviation.

Table 2.

Surgical characteristics for conversion THA and primary THA patients.

	Conversion THA (N = 51)	Primary THA (N = 56)	p value
Laterality			0.02
Left	25 (49.0)	31 (55.4)
Right	26 (51.0)	19 (33.9)
Left & right	0 (0.0)	6 (10.7)
Implant type			0.074
Cementless implant	38 (74.5)	50 (89.3)
Cemented implant	13 (25.5)	6 (10.7)
Operation time (min)	115.8 ± 47.9 (60–295)	100.8 ± 29.4 (55–225)	0.117
Blood loss (ml)	453 ± 432 (50–2000)	430 ± 352 (50–2000)	0.611

Functional status after operation

For functional status after operation, there was an overall significant difference between conversion THA and primary THA (p = 0.002) (Table 3). Column proportions test showed a significantly larger proportion of patients could walk unaided after primary THA compared to conversion THA (p < 0.05). Subgroup analysis by sex showed that for females, an overall significant difference was found between conversion THA and primary THA (p = 0.029). Column proportions test showed a larger proportion of females could walk unaided after primary THA compared to conversion THA (p < 0.05) (Figure 1(a)), whilst no significant difference was found for males (Figure 1(b)) (Table 4).

Table 3.

Clinical outcomes for conversion THA and primary THA patients.

	Conversion THA (N = 51)	Primary THA (N = 56)	p value
Perioperative complications			0.209
No	50 (98.0%)	51 (91.1%)
Yes	1 (2.0%)	5 (8.9%)
Post-operative complications			1.000
No	50 (98.0%)	55 (98.2%)
Yes	1 (2.0%)	1 (1.8%)
Post-operative function status			0.002
Unaided	4 (7.8%)	22 (39.3%)
Stick / Quadripod	23 (45.1%)	16 (28.6%)
Frame	12 (23.5%)	10 (17.9%)
Wheelchair	12 (23.5%)	8 (14.3%)
Mortality			1.000
No	48 (94.1%)	52 (92.9%)
Yes	3 (5.9%)	4 (7.1%)

Table 4.

Post-operative functional status in conversion THA and primary THA cases by sex.

	Female (N = 77)			Male (N = 30)
	Conversion THA (n = 40)	Primary THA (n = 37)	p value^a	Conversion THA (n = 11)	Primary THA (n = 19)	p value^a
Unaided	2 (5%)	11 (29.7%)	<0.05	2 (18.2%)	11 (57.9%)	ns
Stick / Quadripod	19 (47.5%)	11 (29.7%)	ns	4 (36.4%)	5 (26.3%)	ns
Frame	11 (27.5%)	10 (27.0%)	ns	1 (9.1%)	0 (0%)	ns
Wheelchair	8 (20%)	5 (13.5%)	ns	4 (36.4%)	3 (15.8%)	ns

Data expressed as frequency (percentage). THA: total hip arthroplasty; ns: non-significant.

^ap-value was indicated as results of column proportions test adjusted with Bonferroni correction.

Complications and mortality

For complications, six patients (5.6% of entire cohort) were documented with perioperative complications, including fever, acute retention of urine, delirium and transient hypotension, which were all minor complications. Two patients with delayed complications were identified. One patient had foot drop after primary THA and 1 patient had periprosthetic fracture after conversion THA. There were no significant differences between perioperative or delayed complication rates between conversion THA and primary THA (Table 3). For mortality, there were seven cases documented, all of which the cause of death had no direct relationship with THA performed. Causes of death were pneumonia (n = 4), urinary traction infection (n = 1), end-stage renal failure (n = 1) and and heart failure (n = 1).

Outcomes of conversion THA

For the 51 conversion THA (n = 51) in the study, 25 were from hip screws (n = 25), 17 were from a cephalomedullary device (n = 17) and 9 were from hip hemiarthroplasty (n = 9). There were no significant differences for sex, BMI, ASA class, ACCI and usage of antiplatelet or anticoagulation drugs. The patients who had conversion THA from previous hip screw were significantly younger compared to those from cephalonmedullary nail and hip hemiarthroplasty (p = 0.019) (Table 5).

Table 5.

Demographics and effects of cephalomedullary devices used for conversion THA on post-operative functional status, complications and mortality.

	Hip screw (N = 25)	Gamma nail (N = 17)	Hip hemi-arthroplasty (N = 9)	p value
Age at THA (years)	76 ± 10 (59–92)	83 ± 6 (74–94)	82 ± 7 (68–91)	0.019
Female	21 (84.0%)	13 (76.5%)	6 (66.7)	0.487
BMI (kg/m²)	22.8 ± 3.9 (14.5–29.7)	22.2 ± 3.7 (16.2–28.8)	22.2 ± 2.7 (16.2–24.5)	0.819
Reason of surgery				-
Implant complications	2 (8.0%)	9 (52.9%)	9 (100%)
AVN / OA	23 (92.0%)	8 (47.1%)	0 (0%)
Operative time (min)	91 ± 19 (60–121)	128 ± 31 (70–180)	161 ± 83 (80–295)	<0.001
Blood loss (ml)	296 ± 150 (100–900)	546 ± 489 (50–1600)	717 ± 669 (100–2000)	0.304
Post-operative functional status				0.619
Unaided	2 (8.0%)	1 (5.9%)	1 (11.1%)
Stick / Quadripod	10 (40.0%)	7 (41.2%)	6 (66.7%)
Frame	7 (28.0%)	5 (29.4%)	0 (0%)
Wheelchair	6 (24.0%)	4 (23.5%)	2 (22.2%)
Perioperative complications	0 (0%)	0 (0%)	1 (11.1%)	0.176
Delayed complications	0 (0%)	0 (0%)	1 (11.1%)	0.176
Mortality	2 (8.0%)	0 (0%)	0 (0%)	0.667

Data expressed as mean ± SD (range) or frequency (percentage). THA: total hip arthroplasty; AVN: avascular necrosis; OA: osteoarthritis; BMI: body mass index; SD: standard deviation.

The majority of patients who had conversion THA from hip screws were due to avascular necrosis of the femoral head after hip screws fixation. Patients who had conversion THA from cephalomedullary device were due to implant cut-out or avascular necrosis of the femoral head. The cause for conversion THA from hip hemiarthroplasty was acetabular erosion.

The mean operative time for conversion THA from hip screw was 91.2 ± 19.4 min, which was significantly shorter compared to conversion THA with other implants (p < 0.001) (Figure 2). There were no significant differences for intraoperative blood loss between the groups.

There were no significant differences for functional status and complication rates between the different conversion THA groups post-operatively (Table 5). Furthermore, in the subgroup analysis for sex in the functional status, results showed that there was no significant difference between the female subgroup and male subgroup, respectively (p > 0.05).

Discussion

Conversion THA is an established operation that is effective in terms of pain relief and improved function after failure of previous operation.¹² The most common indications for conversion THA include avascular necrosis of the femoral head, acetabular erosion and post-traumatic arthritis¹³ from previous hip joint operations. This is consistent with the findings from our study, where patients that had failed hip operations constituted the patients who underwent conversion THA. In fact, internal fixation for undisplaced neck of femur fractures has overall failure rates reaching as high as 40%.¹⁴ This also explained the preference of arthroplasty surgery in selected elderly patients with neck of femur fracture in recent literature.¹⁵ A previous study showed that there was a positive correlation between ACCI and complications, and direct arthroplasty surgery for patients with Garden I/II and ACCI ≥6 or Garden III/IV and ACCI ≥4 was suggested.¹¹

It is understandable that the average age of conversion THA was higher than primary THA as the procedure would be done after an initial operation. From previous studies, the average age of hip fracture patients was 77.1 years old in mainland China¹⁶ and 84.3 years old in Hong Kong, China.¹⁷ For fragility fractures, sarcopenia is also common as it is found in 95% of male and 64% of female after a fragility fracture.¹⁸ A recent study also showed that 82.2% of hip fracture patients had osteosarcopenia.¹⁹ It is known that increased age is associated with deteriorating mobility and mortality in hip fracture patients.²⁰ Generally, hip fracture patients have a high mortality rate ranging 14–58%.²¹ The poor mobility that exists in general and in correlation with age may explain why the patients in the conversion THA group had worse function compared to primary THA.

Conversion THA had a trend of a longer operative time compared with primary THA as it needs time for removal of previous implants or even broken screws and cut-out¹² and may require more resources with the larger scale of operation anticipated.²² Therefore, much research efforts have also been conducted to enhance osteoporotic fracture healing as well, in which many were pre-clinical studies.²³ According to a previous article, conversion THA took 32 min longer than a primary THA on average (p < 0.0001).²⁴ Another study also revealed longer operative time in conversion THA compared to primary THA (p = 0.015) in their pool of patients with failed hip fracture surgery.²⁵ However, in our study, we did not reach statistical significance which may be explained by the fact that majority of our cases are conversion from hip screws that take less time in general.

According to a previous study found that conversion THA had higher risk of revision due to dislocation and periprosthetic fracture.²⁶ However, in our study, we did not identify patients with post-operative dislocation, but there was one patient that underwent conversion THA from hemiarthroplasty, sustaining a periprosthetic fracture. The reason for the decreased risk of dislocation may be due to the use of dual mobility implants.

The complexity and outcome of conversion THA varies depending on pre-existing anatomy, biology and what type of implantation done. Our study found that a conversion THA surgery from hip screw was faster than a conversion THA surgery from other implants. The outcome of conversion THA from hip screws has been reported to be similar to primary THA,²⁷ and it can provide a safe choice to those who had index operation failure. Conversion THA from other implants, including cephalomedullary device, hemiarthroplasty and acetabular implants often predicts higher surgical complexity, evidenced by its longer operative duration. There are concerns regarding instability and dislocation after conversion THA from hemiarthroplasty²⁸ but this can potentially be addressed by using dual mobility cups to improve the head-to-neck ratio and jump distance again.²⁹ There are studies reporting lower 10-year survivorship by 20% and more complications in patients who had conversion THA from acetabular fixation than primary THA.³⁰

The strength of this study is that there are currently a limited number of existing studies focusing on conversion THA in the Chinese population, and in a city with one of the longest life expectancies. There is also a direct comparison and evaluation of intraoperative and post-operative outcomes between different types of conversion THA. The limitations of this study were the limited sample size and that the study was performed in a single tertiary hospital. Furthermore, this was a retrospective review.

Conclusion

Conversion THA is classically believed to be a technically demanding procedure. Results from this study showed there were no significant differences in intraoperative blood loss, operative time and complication rate between conversion THA and primary THA. There is significantly shorter operation time in conversion THA from hip screws than from other types of implants. With proper patient counselling and patient selection, conversion THA is a treatment option for complications arising from previous hip fracture surgery. However, the function is worse compared to primary THA.

Footnotes

ORCID iD

Ronald Man Yeung Wong

Ethical approval and consent to participate

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. For this retrospective study, formal consent is not required.

Funding

The authors disclosed receipt of the following financial support for the research, authorship and/or publication of this article: This study was funded by the General Research Fund, Research Grants Council (Ref: 14116223).

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship and/or publication of this article.

Data availability

Data is contained within the article. Individual data is unavailable due to privacy or ethical restrictions. Further inquiries can be directed to the corresponding author.

References

Wong

RMY

Cheung

Chow

SKH

, et al. Recommendations on the post-acute management of the osteoporotic fracture – patients with “very-high” re-fracture risk. J Orthop Transl 2022; 37: 94–99.

Bhandari

Swiontkowski

. Management of acute hip fracture. N Engl J Med 2017; 377: 2053–2062.

Wong

RMY

Wong

Liu

, et al. Vibration therapy as an intervention for trochanteric hip fractures – a randomized double-blinded, placebo-controlled trial. J Orthop Translat 2025; 51: 51–58.

Wong

RMY

Law

Lee

, et al. Secondary prevention of fragility fractures: instrumental role of a fracture liaison service to tackle the risk of imminent fracture. Hong Kong Med J 2019; 25: 235–242.

Fernandez

Achten

Parsons

, et al. Cemented or uncemented hemiarthroplasty for intracapsular hip fracture. N Engl J Med 2022; 386: 521–530.

Nauth

Creek

Zellar

, et al. Fracture fixation in the operative management of hip fractures (FAITH): an international, multicentre, randomised controlled trial. Lancet 2017; 389: 1519–1527.

Macheras

Pallis

Tsivelekas

, et al. Acetabular erosion after bipolar hip hemiarthroplasty for femoral neck fracture in elderly patients: a retrospective study. Hip Int 2024; 34: 402–408.

Raiford

Barra

Myers

. A conversion total hip arthroplasty is not a primary total hip arthroplasty. Oper Tech Orthop 2019; 29: 100725.

Wong

RMY

Wai

, et al. Fragility fractures and imminent fracture risk in Hong Kong: one of the cities with longest life expectancies. Arch Osteoporos 2019; 14: 104.

10.

Kheir

Dilley

Speybroeck

, et al. The influence of Dorr type and femoral fixation on outcomes following total hip arthroplasty for acute femoral neck fractures: a multicenter study. J Arthroplasty 2023; 38: 719–725.

11.

Wong

RMY

Chau

, et al. High Charlson Comorbidity Index Score is associated with early fracture-related complication for internal fixation of neck of femur fractures. Sci Rep 2022; 12: 4749.

12.

Srivastav

Mittal

Agarwal

. Total hip arthroplasty following failed fixation of proximal hip fractures. Indian J Orthop 2008; 42: 279–286.

13.

Hernandez

Chalmers

Perry

, et al. Total hip arthroplasty after in situ fixation of minimally displaced femoral neck fractures in elderly patients. J Arthroplasty 2018; 33: 144–148.

14.

Ramadanov

Toma

Herkner

, et al. Factors that influence the complications and outcomes of femoral neck fractures treated by cannulated screw fixation. Sci Rep 2020; 10: 758.

15.

Kim

Park

Lee

. Complications after internal screw fixation of nondisplaced femoral neck fractures in elderly patients: a systematic review. Acta Orthop Traumatol Turc 2020; 54: 337–343.

16.

Zhang

Feng

Wang

, et al. Incidence of and trends in hip fracture among adults in urban China: a nationwide retrospective cohort study. PLoS Med 2020; 17: e1003180.

17.

Wong

RMY

RWK

Chau

, et al. Montreal Cognitive Assessment (MoCA) is highly correlated with 1-year mortality in hip fracture patients. Osteoporos Int 2022; 33: 2185–2192.

18.

Wong

RMY

Wong

Zhang

, et al. The relationship between sarcopenia and fragility fracture – a systematic review. Osteoporos Int 2019; 30: 541–553.

19.

Wong

RMY

Wong

Chau

, et al. Very high prevalence of osteosarcopenia in hip fracture patients: risk and protective factors. J Orthop Surg Res 2025; 20: 423.

20.

Chow

Qin

Wong

, et al. One-year mortality in displaced intracapsular hip fractures and associated risk: a report of Chinese-based fragility fracture registry. J Orthop Surg Res 2018; 13: 235.

21.

Schnell

Friedman

Mendelson

, et al. The 1-year mortality of patients treated in a hip fracture program for elders. Geriatr Orthop Surg Rehabil 2010; 1: 6–14.

22.

Schwarzkopf

Baghoolizadeh

. Conversion total hip arthroplasty: primary or revision total hip arthroplasty. World J Orthop 2015; 6: 750–753.

23.

Wong

RMY

Choy

VMH

, et al. Fibrinolysis as a target to enhance osteoporotic fracture healing by vibration therapy in a metaphyseal fracture model. Bone Joint Res 2021; 10: 41–50.

24.

Hunter

Desmarais

Quilligan

, et al. Conversion total hip arthroplasty in the era of bundled care payments: impacts on costs of care. J Arthroplasty 2023; 38: 998–1003.

25.

Winemaker

Gamble

Petruccelli

, et al. Short-term outcomes of total hip arthroplasty after complications of open reduction internal fixation for hip fracture. J Arthroplasty 2006; 21: 682–688.

26.

Gjertsen

Lie

Fevang

, et al. Total hip replacement after femoral neck fractures in elderly patients: results of 8,577 fractures reported to the Norwegian Arthroplasty Register. Acta Orthop 2007; 78: 491–497.

27.

Mäkelä

Eskelinen

Pulkkinen

, et al. Total hip arthroplasty for primary osteoarthritis in patients fifty-five years of age or older. An analysis of the Finnish arthroplasty registry. J Bone Joint Surg Am 2008; 90: 2160–2170.

28.

Diwanji

Kim

Seon

, et al. Clinical results of conversion total hip arthroplasty after failed bipolar hemiarthroplasty. J Arthroplasty 2008; 23: 1009–1015.

29.

Chalmers

Perry

Hanssen

, et al. Conversion of hip hemiarthroplasty to total hip arthroplasty utilizing a dual-mobility construct compared with large femoral heads. J Arthroplasty 2017; 32: 3071–3075.

30.

Morison

Moojen

Nauth

, et al. Total hip arthroplasty after acetabular fracture is associated with lower survivorship and more complications. Clin Orthop Relat Res 2016; 474: 392–398.