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The Bone & Joint Journal
Vol. 106-B, Issue 6 | Pages 603 - 612
1 Jun 2024
Ahmad A Egeland EH Dybvik EH Gjertsen J Lie SA Fenstad AM Matre K Furnes O

Aims

This study aimed to compare mortality in trochanteric AO/OTA A1 and A2 fractures treated with an intramedullary nail (IMN) or sliding hip screw (SHS). The primary endpoint was 30-day mortality, with secondary endpoints at 0 to 1, 2 to 7, 8 to 30, 90, and 365 days.

Methods

We analyzed data from 26,393 patients with trochanteric AO/OTA A1 and A2 fractures treated with IMNs (n = 9,095) or SHSs (n = 17,298) in the Norwegian Hip Fracture Register (January 2008 to December 2020). Exclusions were made for patients aged < 60 years, pathological fractures, pre-2008 operations, contralateral hip fractures, fractures other than trochanteric A1/A2, and treatments other than IMNs or SHSs. Kaplan-Meier and Cox regression analyses adjusted for type of fracture, age, sex, cognitive impairment, American Society of Anesthesiologists (ASA) grade, and time period were conducted, along with calculations for number needed to harm (NNH).


Orthopaedic Proceedings
Vol. 106-B, Issue SUPP_6 | Pages 55 - 55
2 May 2024
McCann C Ablett A Feng T Macaskill V Oliver W Keating J
Full Access

Subtrochanteric femoral fractures are a subset of hip fractures generally treated with cephalomedullary nail fixation\[1\]. Single lag screw devices are most commonly-used, but integrated dual screw constructs have become increasingly popular\[2,3\]. The aim of this study was to compare outcomes of fixation of subtrochanteric femoral fractures using a single lag screw (Gamma3 nail, GN) with a dual screw device (InterTAN nail, IN). The primary outcome was mechanical failure, defined as lag screw cut-out, back-out, nail breakage or peri-implant fracture. Consecutive adult patients (18yrs) with subtrochanteric femoral fracture treated in a single centre were retrospectively identified using electronic records. Patients that underwent surgical fixation using either a long GN (2010–2017) or IN (2017–2022) were included. Medical records and radiographs were reviewed to identify complications of fixation. Cox regression analysis was used to determine the risk of mechanical failure and secondary outcomes by implant design. Multivariable regression models were used to identify predictors of mechanical failure. The study included 622 patients, 354 in the GN group (median age 82yrs, 72% female) and 268 in the IN group (median age 82yrs, 69% female). The risk of any mechanical failure was increased two-fold in the GN group (HR 2.44 \[95%CI 1.13 to 5.26\]; _p=0.024_). Mechanical failure comprising screw cut-out (_p=0.032_), back-out (_p=0.032_) and nail breakage (_p=0.26_) was only observed in the GN group. Technical predictors of failure included varus >5° for cut-out (OR 19.98 \[2.06 to 193.88\]; _p=0.01_), TAD;25mm for back-out (8.96 \[1.36 to 58.86\]; p=0.022) and shortening 1cm for peri-implant fracture (7.81 \[2.92 to 20.91\]; _p=<0.001_). Our results demonstrate that an intercalated screw construct is associated with a lower risk of mechanical failure compared with the a single lag screw device. Intercalated screw designs may reduce the risk of mechanical complications for patients with subtrochanteric femoral fractures


Orthopaedic Proceedings
Vol. 106-B, Issue SUPP_6 | Pages 3 - 3
2 May 2024
Bayram JM Kanesan H Clement N
Full Access

The aims were to assess whether vitamin D deficiency influenced mortality risk for patients presenting with a hip fracture. A retrospective study was undertaken including all patients aged over 50 years that were admitted with a hip fracture to a single centre during a 24-month period. Serum vitamin D levels were assessed. Patient demographics and perioperative variables and mortality were collected. Cox regression analysis (adjusting for confounding) was utilised to determine the independent association between serum vitamin D level and patient mortality. The cohort consisted of 2075 patients with a mean age of 80.7 years and 1471 (70.9%) were female. 1510 (72.8%) patients had a serum vitamin D level taken, of which 876 (58.0%) were deficient (50nmol/l). The median follow up was 417 (IQR 242 to 651) days. During follow up there were 464 (30.7%) deaths. Survival at 1 year was significantly (p=0.003) lower for patients who were vitamin D deficient (71.7%, 95% confidence intervals (CI) 68.6 to 74.9) compared to those who were not (79.0%, 95% CI 75.9 to 82.3). Vitamin D deficiency was also independently associated with an increased mortality risk at 2-years (HR 1.25, 95% CI 1.03 to 1.53, p=0.025), but not at 1-year (p=0.057). Hip fracture patients with vitamin D deficiency had an increased mortality risk. This risk was independent of confounders at 2 years. The role of measuring vitamin D levels in these patients is unclear. Improved public health policy about vitamin D may be required to reduce deficiency in this patient population


The Bone & Joint Journal
Vol. 106-B, Issue 5 Supple B | Pages 125 - 132
1 May 2024
Carender CN Perry KI Sierra RJ Trousdale RT Berry DJ Abdel MP

Aims

Uncemented implants are now commonly used at reimplantation of a two-stage revision total hip arthoplasty (THA) following periprosthetic joint infection (PJI). However, there is a paucity of data on the performance of the most commonly used uncemented femoral implants – modular fluted tapered (MFT) femoral components – in this setting. This study evaluated implant survival, radiological results, and clinical outcomes in a large cohort of reimplantation THAs using MFT components.

Methods

We identified 236 reimplantation THAs from a single tertiary care academic institution from September 2000 to September 2020. Two designs of MFT femoral components were used as part of an established two-stage exchange protocol for the treatment of PJI. Mean age at reimplantation was 65 years (SD 11), mean BMI was 32 kg/m2 (SD 7), and 46% (n = 109) were female. Mean follow-up was seven years (SD 4). A competing risk model accounting for death was used.


The Bone & Joint Journal
Vol. 106-B, Issue 5 Supple B | Pages 89 - 97
1 May 2024
Scholz J Perka C Hipfl C

Aims. There is little information in the literature about the use of dual-mobility (DM) bearings in preventing re-dislocation in revision total hip arthroplasty (THA). The aim of this study was to compare the use of DM bearings, standard bearings, and constrained liners in revision THA for recurrent dislocation, and to identify risk factors for re-dislocation. Methods. We reviewed 86 consecutive revision THAs performed for dislocation between August 2012 and July 2019. A total of 38 revisions (44.2%) involved a DM bearing, while 39 (45.3%) and nine (10.5%) involved a standard bearing and a constrained liner, respectively. Rates of re-dislocation, re-revision for dislocation, and overall re-revision were compared. Radiographs were assessed for the positioning of the acetabular component, the restoration of the centre of rotation, leg length, and offset. Risk factors for re-dislocation were determined by Cox regression analysis. The modified Harris Hip Scores (mHHSs) were recorded. The mean age of the patients at the time of revision was 70 years (43 to 88); 54 were female (62.8%). The mean follow-up was 5.0 years (2.0 to 8.75). Results. DM bearings were used significantly more frequently in elderly patients (p = 0.003) and in hips with abductor deficiency (p < 0.001). The re-dislocation rate was 13.2% for DM bearings compared with 17.9% for standard bearings, and 22.2% for constrained liners (p = 0.432). Re-revision-free survival for DM bearings was 84% (95% confidence interval (CI) 0.77 to 0.91) compared with 74% (95% CI 0.67 to 0.81) for standard articulations, and 67% (95% CI 0.51 to 0.82) for constrained liners (p = 0.361). Younger age (hazard ratio (HR) 0.92 (95% CI 0.85 to 0.99); p = 0.031), lower comorbidity (HR 0.44 (95% CI 0.20 to 0.95); p = 0.037), smaller heads (HR 0.80 (95% CI 0.64 to 0.99); p = 0.046), and retention of the acetabular component (HR 8.26 (95% CI 1.37 to 49.96); p = 0.022) were significantly associated with re-dislocation. All DM bearings which re-dislocated were in patients with abductor muscle deficiency (HR 48.34 (95% CI 0.03 to 7,737.98); p = 0.303). The radiological analysis did not reveal a significant relationship between restoration of the geometry of the hip and re-dislocation. The mean mHHSs significantly improved from 43 points (0 to 88) to 67 points (20 to 91; p < 0.001) at the final follow-up, with no differences between the types of bearing. Conclusion. We found that the use of DM bearings reduced the rates of re-dislocation and re-revision in revision THA for recurrent dislocation, but did not guarantee stability. Abductor deficiency is an important predictor of persistent instability. Cite this article: Bone Joint J 2024;106-B(5 Supple B):89–97


The Bone & Joint Journal
Vol. 106-B, Issue 5 Supple B | Pages 112 - 117
1 May 2024
Hickie KL Neufeld ME Howard LC Greidanus NV Masri BA Garbuz DS

Aims

There are limited long-term studies reporting on outcomes of the Zimmer Modular Revision (ZMR) stem, and concerns remain regarding failure. Our primary aim was to determine long-term survival free from all-cause revision and stem-related failure for this modular revision stem in revision total hip arthroplasty (THA). Secondary aims included evaluating radiological and functional outcomes.

Methods

We retrospectively identified all patients in our institutional database who underwent revision THA using the ZMR system from January 2000 to December 2007. We included 106 patients (108 hips) with a mean follow-up of 14.5 years (2.3 to 22.3). Mean patient age was 69.2 years (37.0 to 89.4), and 51.9% were female (n = 55). Indications for index revision included aseptic loosening (73.1%), infection (16.7%), fracture (9.3%), and stem fracture (0.9%). Kaplan-Meier analysis was used to determine the all-cause and stem-related failure revision-free survival. At most recent follow-up, Oxford Hip Scores (OHS) were collected, and radiological stem stability was determined using the Engh classification.


Aims

The aims of this study were to evaluate the incidence of reoperation (all cause and specifically for periprosthetic femoral fracture (PFF)) and mortality, and associated risk factors, following a hemiarthroplasty incorporating a cemented collarless polished taper slip stem (PTS) for management of an intracapsular hip fracture.

Methods

This retrospective study included hip fracture patients aged 50 years and older treated with Exeter (PTS) bipolar hemiarthroplasty between 2019 and 2022. Patient demographics, place of domicile, fracture type, delirium status, American Society of Anesthesiologists (ASA) grade, length of stay, and mortality were collected. Reoperation and mortality were recorded up to a median follow-up of 29.5 months (interquartile range 12 to 51.4). Cox regression was performed to evaluate independent risk factors associated with reoperation and mortality.


The Bone & Joint Journal
Vol. 106-B, Issue 4 | Pages 352 - 358
1 Apr 2024
Wilson JM Trousdale RT Bedard NA Lewallen DG Berry DJ Abdel MP

Aims

Dislocation remains a leading cause of failure following revision total hip arthroplasty (THA). While dual-mobility (DM) bearings have been shown to mitigate this risk, options are limited when retaining or implanting an uncemented shell without modular DM options. In these circumstances, a monoblock DM cup, designed for cementing, can be cemented into an uncemented acetabular shell. The goal of this study was to describe the implant survival, complications, and radiological outcomes of this construct.

Methods

We identified 64 patients (65 hips) who had a single-design cemented DM cup cemented into an uncemented acetabular shell during revision THA between 2018 and 2020 at our institution. Cups were cemented into either uncemented cups designed for liner cementing (n = 48; 74%) or retained (n = 17; 26%) acetabular components. Median outer head diameter was 42 mm. Mean age was 69 years (SD 11), mean BMI was 32 kg/m2 (SD 8), and 52% (n = 34) were female. Survival was assessed using Kaplan-Meier methods. Mean follow-up was two years (SD 0.97).


Bone & Joint Open
Vol. 5, Issue 2 | Pages 123 - 131
12 Feb 2024
Chen B Duckworth AD Farrow L Xu YJ Clement ND

Aims

This study aimed to determine whether lateral femoral wall thickness (LWT) < 20.5 mm was associated with increased revision risk of intertrochanteric fracture (ITF) of the hip following sliding hip screw (SHS) fixation when the medial calcar was intact. Additionally, the study assessed the association between LWT and patient mortality.

Methods

This retrospective study included ITF patients aged 50 years and over treated with SHS fixation between 2019 and 2021 at a major trauma centre. Demographic information, fracture type, delirium status, American Society of Anesthesiologists grade, and length of stay were collected. LWT and tip apex distance were measured. Revision surgery and mortality were recorded at a mean follow-up of 19.5 months (1.6 to 48). Cox regression was performed to evaluate independent risk factors associated with revision surgery and mortality.


Orthopaedic Proceedings
Vol. 106-B, Issue SUPP_4 | Pages 5 - 5
8 Feb 2024
Ablett AD McCann C Feng T Macaskill V Oliver WM Keating JF
Full Access

This study compares outcomes of fixation of subtrochanteric femoral fractures using a single lag screw (Gamma3 nail, GN) with a dual lag screw device (InterTAN nail, IN). The primary outcome was mechanical failure, defined as lag screw cut-out, back-out, nail breakage or peri-implant fracture. Technical factors associated with mechanical failure were also identified. All adult patients (>18yrs) with a subtrochanteric femoral fracture treated in a single centre were retrospectively identified using electronic records. Included patients underwent surgical fixation using either a long GN (2010–2017) or IN (2017–2022). Cox regression analysis was used to determine the risk of mechanical failure and technical predictors of failure. The study included 587 patients, 336 in the GN group (median age 82yrs, 73% female) and 251 in the IN group (median age 82yrs, 71% female). The IN group exhibited a higher prevalence of osteoporosis (p=0.002) and CKD□3 (p=0.007). There were no other baseline differences between groups. The risk of any mechanical failure was increased two-fold in the GN group (HR 2.51, p=0.020). Mechanical failure comprising screw cut-out (p=0.040), back-out (p=0.040) and nail breakage (p=0.51) was only observed in the GN group. The risk of peri-implant fracture was similar between the groups (HR 1.10, p=0.84). Technical predictors of mechanical included varus >5° for cut-out (HR 15.61, p=0.016), TAD>25mm for back-out (HR 9.41, p=0.020) and shortening >1cm for peri-implant fracture (HR 6.50, p=<0.001). Dual lag screw designs may reduce the risk of mechanical complications for patients with subtrochanteric femoral fractures


The Bone & Joint Journal
Vol. 106-B, Issue 2 | Pages 189 - 194
1 Feb 2024
Donald N Eniola G Deierl K

Aims

Hip fractures are some of the most common fractures encountered in orthopaedic practice. We aimed to identify whether perioperative hypotension is a predictor of 30-day mortality, and to stratify patient groups that would benefit from closer monitoring and early intervention. While there is literature on intraoperative blood pressure, there are limited studies examining pre- and postoperative blood pressure.

Methods

We conducted a prospective observational cohort study over a one-year period from December 2021 to December 2022. Patient demographic details, biochemical results, and haemodynamic observations were taken from electronic medical records. Statistical analysis was conducted with the Cox proportional hazards model, and the effects of independent variables estimated with the Wald statistic. Kaplan-Meier survival curves were estimated with the log-rank test.


The Bone & Joint Journal
Vol. 106-B, Issue 2 | Pages 144 - 150
1 Feb 2024
Lynch Wong M Robinson M Bryce L Cassidy R Lamb JN Diamond O Beverland D

Aims

The aim of this study was to determine both the incidence of, and the reoperation rate for, postoperative periprosthetic femoral fracture (POPFF) after total hip arthroplasty (THA) with either a collared cementless (CC) femoral component or a cemented polished taper-slip (PTS) femoral component.

Methods

We performed a retrospective review of a consecutive series of 11,018 THAs over a ten-year period. All POPFFs were identified using regional radiograph archiving and electronic care systems.


Bone & Joint 360
Vol. 13, Issue 1 | Pages 19 - 22
1 Feb 2024

The February 2024 Foot & Ankle Roundup360 looks at: Survival of revision ankle arthroplasty; Tibiotalocalcaneal nail for the management of open ankle fractures in the elderly patient; Accuracy of a patient-specific total ankle arthroplasty instrumentation; Fusion after failed primary ankle arthroplasty: can it work?; Treatment options for osteochondral lesions of the talus; Managing hair tourniquet syndrome of toe: a rare emergency; Ultrasound-guided collagenase therapy for recurrent plantar fibromatosis: a promising line of therapy?.


The Bone & Joint Journal
Vol. 106-B, Issue 1 | Pages 28 - 37
1 Jan 2024
Gupta S Sadczuk D Riddoch FI Oliver WM Davidson E White TO Keating JF Scott CEH

Aims

This study aims to determine the rate of and risk factors for total knee arthroplasty (TKA) after operative management of tibial plateau fractures (TPFs) in older adults.

Methods

This is a retrospective cohort study of 182 displaced TPFs in 180 patients aged ≥ 60 years, over a 12-year period with a minimum follow-up of one year. The mean age was 70.7 years (SD 7.7; 60 to 89), and 139/180 patients (77.2%) were female. Radiological assessment consisted of fracture classification; pre-existing knee osteoarthritis (OA); reduction quality; loss of reduction; and post-traumatic OA. Fracture depression was measured on CT, and the volume of defect estimated as half an oblate spheroid. Operative management, complications, reoperations, and mortality were recorded.


Bone & Joint Open
Vol. 4, Issue 12 | Pages 932 - 941
6 Dec 2023
Oe K Iida H Otsuki Y Kobayashi F Sogawa S Nakamura T Saito T

Aims

Although there are various pelvic osteotomies for acetabular dysplasia of the hip, shelf operations offer effective and minimally invasive osteotomy. Our study aimed to assess outcomes following modified Spitzy shelf acetabuloplasty.

Methods

Between November 2000 and December 2016, we retrospectively evaluated 144 consecutive hip procedures in 122 patients a minimum of five years after undergoing modified Spitzy shelf acetabuloplasty for acetabular dysplasia including osteoarthritis (OA). Our follow-up rate was 92%. The mean age at time of surgery was 37 years (13 to 58), with a mean follow-up of 11 years (5 to 21). Advanced OA (Tönnis grade ≥ 2) was present preoperatively in 16 hips (11%). The preoperative lateral centre-edge angle ranged from -28° to 25°. Survival was determined by Kaplan-Meier analysis, using conversions to total hip arthroplasty as the endpoint. Risk factors for joint space narrowing less than 2 mm were analyzed using a Cox proportional hazards model.


The Bone & Joint Journal
Vol. 105-B, Issue 12 | Pages 1321 - 1326
1 Dec 2023
Schlenzka T Serlo J Viljakka T Tallroth K Helenius I

Aims

We aimed to assess the cumulative risk of total hip arthroplasty (THA) from in situ fixation for slipped capital femoral epiphysis (SCFE) after a follow-up of almost 50 years.

Methods

In this study, 138 patients with 172 affected hips treated with in situ fixation were evaluated retrospectively. A total of 97 patients (70%) were male and the mean age was 13.6 years (SD 2.1); 35 patients (25%) had a bilateral disease. The median follow-up time was 49 years (interquartile range 43 to 55). Basic demographic, stability, and surgical details were obtained from patient records. Preoperative radiographs (slip angle; SA) were measured, and data on THA was gathered from the Finnish National Arthroplasty Register.


Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_16 | Pages 21 - 21
17 Nov 2023
Matar H van Duren B Berber R Bloch B James P Manktelow A
Full Access

Abstract. Objectives. Total hip replacement (THR) is one of the most successful and cost-effective interventions in orthopaedic surgery. Dislocation is a debilitating complication of THR and managing an unstable THR constitutes a significant clinical challenge. Stability in THR is multifactorial and is influenced by surgical, patient and implant related factors. It is established that larger diameter femoral heads have a wider impingement-free range of movement and an increase in jump distance, both of which are relevant in reducing the risk of dislocation. However, they can generate higher frictional torque which has led to concerns related to increased wear and loosening. Furthermore, the potential for taper corrosion or trunnionosis is also a potential concern with larger femoral heads, particularly those made from cobalt-chrome. These concerns have meant there is hesitancy among surgeons to use larger sized heads. This study presents the comparison of clinical outcomes for different head sizes (28mm, 32mm and 36mm) in primary THR for 10,104 hips in a single centre. Methods. A retrospective study of all consecutive patients who underwent primary THR at our institution between 1st April 2003 and 31st Dec 2019 was undertaken. Institutional approval for this study was obtained. Demographic and surgical data were collected. The primary outcome measures were all-cause revision, revision for dislocation, and all-cause revision excluding dislocation. Continuous descriptive statistics used means, median values, ranges, and 95% confidence intervals where appropriate. Kaplan-Meier survival curves were used to estimate time to revision. Cox proportional hazard regression analysis was used to compare revision rates between the femoral head size groups. Adjustments were made for age at surgery, gender, primary diagnosis, ASA score, articulation type, and fixation method. Results. 10,104 primary THRs were included; median age 68.6 years with 61.5% females. A posterior approach was performed in 71.6%. There were 3,295 hips with 28 mm heads (32.6%), 4,858 (48.1%) with 32 mm heads and 1,951 (19.3%) with 36 mm heads. Overall rate of revision was 1.7% with the lowest rate recorded for the 36mm group (2.7% vs. 1.3% vs. 1.1%). Cox regression analysis showed a decreased risk of all-cause revision for 32mm & 36mm head sizes as compared to 28mm; this was statistically significant for the 32mm group (p = 0.01). Risk of revision for dislocation was significantly reduced in both 32mm (p = 0.03) and 36mm (p = 0.03) head sizes. Analysis of all cause revision excluding dislocation showed no significant differences between head sizes. Conclusion. There was a significantly reduced risk of revision for all causes, but particularly revision for dislocation with larger head sizes (36mm & 32mm vs. 28mm). Concerns regarding increased risk of early revision for aseptic loosening, polyethylene wear or taper corrosion with larger heads appear to be unfounded in this cohort of 10,104 patients with a mean of 6.0-year follow-up. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project


The Bone & Joint Journal
Vol. 105-B, Issue 11 | Pages 1216 - 1225
1 Nov 2023
Fujiwara T Kunisada T Nakata E Mitsuhashi T Ozaki T Kawai A

Aims

Clear cell sarcoma (CCS) of soft-tissue is a rare melanocytic subtype of mesenchymal malignancy. The aim of this study was to investigate the clinical and therapeutic factors associated with increased survival, stratified by clinical stage, in order to determine the optimal treatment.

Methods

The study was a retrospective analysis involving 117 patients with histologically confirmed CCS, between July 2016 and November 2017, who were enrolled in the Bone and Soft Tissue Tumour Registry in Japan.


Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_14 | Pages 5 - 5
10 Oct 2023
Bayram J Kanesan H Clement N
Full Access

The aims were to assess whether vitamin D deficiency influenced mortality risk for patients presenting with a hip fracture. A retrospective study was undertaken including all patients aged over 50 years that were admitted with a hip fracture to a single centre during a 24-month period. Serum vitamin D levels were assessed. Patient demographics and perioperative variables and mortality were collected. Cox regression analysis (adjusting for confounding) was utilised to determine the independent association between serum vitamin D level and patient mortality. The cohort consisted of 2075 patients with a mean age of 80.7 years and 1471 (70.9%) were female. 1510 (72.8%) patients had a serum vitamin D level taken, of which 876 (58.0%) were deficient (<50nmol/l). The median follow up was 417 (IQR 242 to 651) days. During follow up there were 464 (30.7%) deaths. Survival at 1 year was significantly (p = 0.003) lower for patients who were vitamin D deficient (71.7%, 95% confidence intervals (CI) 68.6 to 74.9) compared to those who were not (79.0%, 95% CI 75.9 to 82.3). Vitamin D deficiency was also independently associated with an increased mortality risk at 2-years (HR 1.42, 95% CI 1.17 to 1.71, p = 0.03), but not at 1-year (p = 0.08). Hip fracture patients with vitamin D deficiency had an increased mortality risk. This risk was independent of confounders at 2 years. The role of measuring vitamin D levels in these patients is unclear. Improved public health policy about vitamin D may be required to reduce deficiency in this patient population


The Bone & Joint Journal
Vol. 105-B, Issue 9 | Pages 1020 - 1029
1 Sep 2023
Trouwborst NM ten Duis K Banierink H Doornberg JN van Helden SH Hermans E van Lieshout EMM Nijveldt R Tromp T Stirler VMA Verhofstad MHJ de Vries JPPM Wijffels MME Reininga IHF IJpma FFA

Aims. The aim of this study was to investigate the association between fracture displacement and survivorship of the native hip joint without conversion to a total hip arthroplasty (THA), and to determine predictors for conversion to THA in patients treated nonoperatively for acetabular fractures. Methods. A multicentre cross-sectional study was performed in 170 patients who were treated nonoperatively for an acetabular fracture in three level 1 trauma centres. Using the post-injury diagnostic CT scan, the maximum gap and step-off values in the weightbearing dome were digitally measured by two trauma surgeons. Native hip survival was reported using Kaplan-Meier curves. Predictors for conversion to THA were determined using Cox regression analysis. Results. Of 170 patients, 22 (13%) subsequently received a THA. Native hip survival in patients with a step-off ≤ 2 mm, > 2 to 4 mm, or > 4 mm differed at five-year follow-up (respectively: 94% vs 70% vs 74%). Native hip survival in patients with a gap ≤ 2 mm, > 2 to 4 mm, or > 4 mm differed at five-year follow-up (respectively: 100% vs 84% vs 78%). Step-off displacement > 2 mm (> 2 to 4 mm hazard ratio (HR) 4.9, > 4 mm HR 5.6) and age > 60 years (HR 2.9) were independent predictors for conversion to THA at follow-up. Conclusion. Patients with minimally displaced acetabular fractures who opt for nonoperative fracture treatment may be informed that fracture displacement (e.g. gap and step-off) up to 2 mm, as measured on CT images, results in limited risk on conversion to THA. Step-off ≥ 2 mm and age > 60 years are predictors for conversion to THA and can be helpful in the shared decision-making process. Cite this article: Bone Joint J 2023;105-B(9):1020–1029