Cemented total hip replacement following acetabular fracture

Abstract

Aims: Following acetabular fracture, post-traumatic osteoarthritis (PTOA) and avascular

necrosis (AVN) necessitate total hip replacement (THR) in up to 23% of patients. The aim of

this study was to examine outcomes of cemented THR following acetabular fracture.

Patients & Methods: From 1992 to 2016, 51 consecutive patients (34 male) with mean age

57 (25-87) underwent cemented THR at mean 6.5 years (0.1 to 25) following acetabular

fracture. Thirty-nine had undergone surgical fixation and 12 had been treated non-

operatively. Thirteen patients died at mean 10.2 years after THR (0.6 to 19). Patients were

assessed preoperatively, at 1 year and at final follow up (mean 9.1 years, 0.5 to 23) using

the Oxford Hip Score (OHS). Implant survivorship was assessed. An age and sex matched

cohort of THRs performed for non-traumatic OA or AVN (n=102) were used against which to

compare complications and PROMs.

Results: Patients with AVN (mean 2.2 years) or protrusio (2.2) required THR earlier than

those with PTOA (9.4) or infection (8.0, p=0.03). Ten contained and 5 uncontained defects

were managed with autograft (n=11), bulk allograft (n=1), or trabecular metal (n=3). Initial

fracture management (ORIF or non-operative), THR timing (>/<1 year), and age (>/<55

years) had no significant effects on OHS or 10 year survival, though outcomes were superior

in non-operatively managed fractures, and patients <55 years. Six THRs were revised at

mean 12 years (5-23) with 10 year all cause survival of 92% (95% CI 80.8 to 100%). THR

complication rates (all complications, heterotopic ossification, leg length discrepancy

>10mm) were significantly higher following acetabular fracture compared to atraumatic

OA/AVN and OHSs were inferior: 1 year OHS (35.7 Vs 40.2, p=0.026); and final follow-up

OHS (33.6 Vs 40.9, p=0.008).

Conclusion: Cemented THR is durable following acetabular fracture. Higher complication

rates and poorer PROMs reflect the complex nature of these cases.

Introduction

Following acetabular fracture, radiographic post-traumatic osteoarthritis is present in 27-37%

of patients at long-term follow up [1]. An additional 5.6% of patients develop avascular

necrosis (AVN) [1]. These late complications give a conversion rate to total hip replacement

(THR) of 8-23% [1-3]. Known risk factors for THR include age >55 years, posterior

wall/column injuries, femoral head damage, dislocation and incongruent reductions [3].

When THR is required, inferior outcomes and high complication rates, particularly infection,

dislocation and heterotopic ossification (HO) are reported [4-6], giving inferior survival

compared to THR for osteoarthritis [7]. Historical reports of aseptic loosening rates of 50% at

10 years for cemented acetabular components performed following acetabular fracture [4]

resulted in recommendations that only uncemented cups be used in these cases [8]. In the

current literature, cemented THRs following acetabular fracture are scarce [6]. Where

cemented implants have been used, results are reported in combination with uncemented

implants, making conclusions pertaining to implant type difficult. To our knowledge survival

and patient reported outcomes (PROMs) of modern cemented THR have not been reported

in this patient group.

The aim of this study was to examine the survival and outcomes of late cemented THR

following acetabular fracture and to perform a matched cohort study comparing these to

THR in patients with atraumatic osteoarthritis. The primary outcome measure was the

Oxford Hip Score (OHS) with secondary outcome measures including complications,

radiographic outcome, patient satisfaction and survivorship.

Patients and Methods

From 1988 to 2010, 527 acetabular fractures were treated at our institution. Of these

patients, 3 (0.5%) elderly patients with unreconstructable acetabular fractures were treated

with acute THR. A further 60 patients (11.4%) went on to require salvage THR for late

complications of acetabular fracture from 1992-2016: 2 hybrid THRs; 7 uncemented THRs;

and 51 cemented THRs. The 51 cemented THRs form our study group. All procedures were

performed by 14 consultant orthopaedic surgeons with interests in lower limb arthroplasty.

Medical notes were reviewed and data collected regarding patient demographics, fracture

date and management, Letournel classification [9], mechanism of failure and reoperations.

Operation notes were examined and surgical approach, bone defect classification and

management, intra-operative complications and implant type were recorded. Early and late

complications and reoperations were recorded up to final follow-up. Pelvic radiographs were

examined by one author (CEHS) who had no clinical contact with the patients (Figure 1). HO

was graded according to the Brooker classification [10]. Leg lengths (using the inter-teardrop

line to lesser trochanter method [11]), femoral offset (the horizontal distance from femoral

head centre to anatomical axis of femur [11]) and centre of rotation (horizontal distance from

pubic symphysis to centre of femoral head) were measured (Figure 1b). Mismatches in

femoral offset and centre of rotation were calculated by comparison with the non-operated

hip. Periprosthetic radiolucencies were reported in femoral [12] and acetabular regions [13].

If radiolucencies were present, all radiographs pertaining to that THR were examined to

assess progression.

In August 2016 deceased patients were identified (n=13) and date of death confirmed. All

remaining patients were sent a follow-up questionnaire containing the Oxford Hip Score

(OHS)[14], EQ-5D [15] and patient satisfaction questions. Those who did not reply were

contacted by telephone and scores recorded. The OHS is a validated hip specific outcome

measure that minimises the influence of comorbidities[14]. It consists of 12 questions with

five possible answers giving a score from 0-48 (higher scores represent better function). For

patients who had undergone THR after 1996 (n=46), prospectively collected preoperative

and 1 year OHSs were also available. Satisfaction was assessed via a 5 point Likert scale

with the options “very satisfied”, “satisfied”, ”uncertain”, “dissatisfied” and “very dissatisfied”.

The outcomes (PROMs, complication rates and survivorship) of this acetabular fracture

cohort were compared to a cohort of consecutive age and sex matched patients identified

from our arthroplasty database who underwent THR for osteoarthritis or AVN between 2006

and 2010. A ratio of 2:1 gave 102 patients for whom preoperative, 1 year and long-term

(mean 7.6 years, range 5.7-9.7) PROMs data, radiographic data and clinical data were

available.

Analysis

Statistical analysis was performed using Statistical Package for Social Sciences version 21.0

(SPSS Inc., Chicago, IL, USA). Parametric (unpaired T-tests) and non-parametric (Mann-

Whitney U) tests were used as appropriate to assess continuous variables for significant

differences between THR cohorts. One way ANOVA was used to compare continuous

variables with multiple groups such as age at fracture and time to THR for different modes of

fracture fixation failure. Nominal categorical variables were assessed using a Chi square or

Fisher’s exact test. Survival analysis was undertaken using Kaplan Meier analysis with the

endpoints failure for any reason and revision.

Results

Fifty-one patients underwent 51 THRs for late complications of acetabular fracture. Thirty

four (67%) were male. Mean age at fracture was 51 years (range, 17-87 years). Thirty-nine

had undergone open reduction an internal fixation (ORIF) and 12 were treated non-

operatively (undisplaced fracture n=10, unreconstructable quadrilateral plate (n=2)). Figure 2

shows the fracture types. All fractures were closed. In the 39 treated with ORIF, approaches

included: 3 ilio-inguinal; 24 Kocher-Langenbeck; 5 tri-radiate; 3 combined

Ilio-inguinal/Kocher-Langenbeck; 1 Stoppa; 1 Southern; and was unknown in 2. THR was

performed at mean 6.5 years following fracture (range, 0.1-25) at mean age 57 years (range,

25-87). Time from fracture to THR did not differ between fractures treated with ORIF

(7.3±7.7 years, range 0.12 to 25) and those non-operatively managed (5.2±7.3, 0.2 to 22,

p=0.191 Mann Whitney U-test). Thirteen patients died at mean 10.2 years following THR

(range 0.6 to 19). Mean length of follow up for those alive (38/51) was 9.1 years (range 0.5

to 23). Two patients were lost to follow up at 2 years and 6 years following THA.

Indications for THR are shown in Table 1. At THR, 30 patients had retained metalwork from

ORIF. Age at fracture and age at THR displayed a linear relationship in patients over 45

years at fracture (Figure 3). Time to THR differed significantly between patients <45 years

(n=21, mean 12 years, range 0.8-25) and those >45 who required salvage THR earlier after

injury (n=30, mean 2.3, 0.1 -15.4, p<0.001, Mann Whitney U test). Time to THR differed for

different modes of failure (Table 1 ANOVA p=0.031): patients with AVN or PTOA with

protrusio required THR earlier (mean 2.2 years) than those following infected ORIF or

PTOA (mean 9.3 years, p=0.003 Mann Whitney U). Patients with infected ORIF or PTOA

were older than those with other indications both at fracture (60.4±16.5 Vs 43.6±18,

p=0.003, unpaired T-test, 95%CI 5.9 to 27.8) and at THR (62.6±16.3 Vs. 52.9±14.4,

p=0.043, unpaired T-test, 95%CI 0.3 to 19.2). Of 17/51 patients with femoral head

dislocation at fracture, 9 developed AVN. Acetabular fibrous non-unions were found at THR

in 3 patients (5.9%). The Letournel classification.did not correlate with the development of

AVN or mode of failure requiring THR.

Surgical data

An anterolateral approach was used for 12/51 THRs, and a posterior approach in 34/51. All

acetabular components (50 contemporary cups (Stryker Orthopaedics, Mahwah, New

Jersey) and 1 unknown) and femoral stems were cemented (44 Exeter stems, Stryker

Orthopaedics), 6 Charnley (Depuy Synthes, Johnson & Johnson, Raynham,

Massachusetts), and 1 Olympia (Zimmer Biomet). Fifteen patients (29%) had bone defects

noted at THR: 7 small contained defects treated with autograft; 4 uncontained superior

defects treated with femoral head allograft (figure 4) or trabecular metal; 3 contained non-

unions treated with autograft +/- trabecular metal; and 1 medial wall defect treated with

autograft. Two trabecular metal shells (with cemented cups) and one wedge augment were

used. Bone defect presence was not associated with age, gender, fracture classification or

initial fracture management. Metal on polyethylene bearings were used in 46 patients and

ceramic on polyethylene in 5.

Complications

There were no intraoperative complications. Table 2 details early and late complications.

Early complications included a dislocation on day 6 managed with closed reduction, an

infection on day 17 treated with debridement and implant retention with head exchange and

a death on day 2 of a 41 year old male (Table 2). Late complications occurred in 10 patients

(19.6%) (Table 2). Following fracture, and prior to THR, 7 patients (14%) had HO. Eighteen

patients (35%) had HO following THR, including 3 (6%) with Brooker grade 3/4. Both

patients with grade 4 had HO following fracture. All patients with grade 3/4 HO had

undergone previous ORIF via a Kocher-Langenbeck approach. Overall, surgical approach at

ORIF did not affect HO development (p=0.581, Chi squared). There were no new sciatic

nerve palsies, but one patient had a residual palsy dating from ORIF.

Of the 3 patients with infection following ORIF necessitating THR after metalwork removal

+/- Girdlestone procedure, none developed infection following salvage THR. In these

patients, THR was performed at 1, 9 and 13 years following fracture. Infections occurred

after THR in 3 (6%) patients: at 5 years in a 55 year old healthy male; at 13 years in a 68

year old healthy female; and at 4 weeks in a 47 year old previous intravenous drug abuser

with Hepatitis C. Two had retained metalwork at THR (p=0.46 Fisher’s exact test).

Radiographic Outcome

Mean leg length discrepancy (LLD) was -3.4±13.0mm (range, -37 to 18mm) and a

LLD>10mm occurred in 19/36 (53%) patients in whom it was measurable. Mean change in

offset was 1.8±13.2mm (range,-52 to 21mm) with 9/34 patients (20%) having mismatches of

>10mm. Mean change in centre of rotation was 1.0±9.6mm (range, -23 to 19mm) with 10/34

patients (20%) mismatched by >10mm (Figure 6). Radiolucent lines were present in a single

acetabular zone in 6/51 (12%), two zones in 4/51 (8%) and 3 zones 3/51 (6%). In addition to

those revised, one patient had progressive radiolucent lines in all acetabular zones and was

considered to be failing.

Survival

Over the study period 6/51 THRs were revised at mean 15.5 years (range 5.9 to 23 years,

Table 3). One additional patient had acetabular component aseptic loosening at 16.9 years

but died prior to revision, and one patient had asymptomatic radiographic loosening at 4.5

years. At ten years, 2 of 20 THRs had been revised with 3 of 13 revised by 15 years (Table

3). This gave an all-cause survival with revision as an endpoint of 92% at 10 years (95%

Confidence Interval, 80.8 to 100%) and 85% at 15 years (95%CI, 67.8 to 100%) (Figure 5).

For failure with or without revision 10 year survival is 90.4% (95%CI 79.6 to 100%), 15 year

82.9 (95%CI 65.6 to 100%). Comparisons of 10 year survival for the following patient

subgroups is shown in Table 4: ORIF (n=39) Vs conservative (n=12) fracture management;

early (<1 year, n=17) Vs late (>1 year, n=34) THR; and younger (<55 years at fracture,

n=27) and older (>55 years at fracture, n=24) patients.

PROMs

After patients who were deceased (n=13), had been revised (still alive n=5), and who were

<1 year following THR (n=2) were excluded, 31 patients were available for long term

PROMs. Two were lost to follow up at 2 and 6 years following THR, thus long term PROMs

data was available for 29 patients.

Oxford hip score improved significantly following THR (p=0.002, repeated measure ANOVA,

Table 2, Figure 7). There was no significant correlation between age and postoperative

OHS. There was no difference in long term OHS in those with (37±17.1, 3-48) and without

(32.7±13.1, 5-48) bone defects at THR (p=0.511, Mann Whitney U Test). OHS did not differ

in patients with or without a LLD >10mm, offset mismatch >10mm or a centre of rotation

mismatch >10mm. There was no significant difference in OHS at one year or long term

follow-up for patients treated with THR following ORIF or conservative management, at <

1year or >1 year post-fracture or in patients younger or older than 55 years at fracture (Table

4).

Three patients (11% (3/28)) were dissatisfied with their THR following acetabular fracture:

one had an early infection treated with debridement and implant retention; and one had a leg

length discrepancy with 35mm of shortening and an 11mm offset deficit. All 3 had well fixed

implants with no radiolucencies.

Matched Cohort Study

A matched cohort of 102 patients with mean age 55.6±14.6 years (range 17-81) and mean

length of follow up 6.6±2.0 (range 4 to 10.5) was identified. Indication for THR was primary

OA in 73/102, secondary OA (atraumatic) in 20/102 and AVN in 9/102. Table 2 compares

fracture and matched groups.

Radiographic outcomes

Comparing fracture and matched groups, there were no significant differences in mean LLD

(-3.4±13.0mm Vs -0.8±.6.3, p=0.264 unpaired T-test), change in offset (1.8±13.2 Vs -

1.4±7.5, p=0.188) or change in centre of rotation (1.0±9.6 Vs -0.7±7.2, p=0.358) (Figure 6).

However, there were more outliers in the fracture group (Figure 6). A leg length discrepancy

of >10mm (long or short) was more likely in the fracture group (19/36, 53% Vs 8/85, 9%

p<0.001, Chi squared). There were no significant differences in femoral offset mismatch

>10mm (9/34, 20% Vs 14/85, 17%, p=0.350 Chi squared) or centre of rotation mismatch

>10mm (10/34, 20% Vs 11/85, 13%, p=0.071, Chi squared). Radiolucent lines did not differ

between fracture and matched groups: single acetabular zone 6/51 (12%) Vs 25/102 (25%);

two zones in 4/51 (8%) Vs 6/102 (6%); and 3 zones 3/51 (6%) Vs 3/102 (3%) (p=0.315, Chi

squared).

Complications

There were more early complications in the fracture group (p=0.009, Chi squared, Table 2)

and a higher rate of all complications (13/51 Vs 10/102, p=0.007, Chi squared). Heterotopic

ossification was more common in the fracture group (p<0.001, Chi squared). Dislocation,

infection and aseptic loosening were more common in the fracture group, but not

significantly so.

In the matched THR cohort 4 (6%) patients developed infection: a 56 year old male with

Hepatitis C, cirrhosis and portal hypertension (infected at 7 years); a 55 year old male with

type 2 diabetes, pancreatic failure and a BMI of 47 (3 years); an otherwise well 54 year old

male (1 year); and a 35 year old male with haematogenous spread from discitis (5 years).

The risks of complications were highest in the fracture group: relative risk (RR) of any

complication was 2.11 (95%CI 1.3 to 3.4); RR of dislocation 2.47 (95%CI 1.3 to 4.6); RR of

aseptic loosening 2.87 (95%CI 1.7 to 4.8); RR of any HO 3.49 (95%CI 2.2 to 5.5); and RR of

HO grade 3 or 4 2.80 (95%CI 1.5 to 5.2).

PROMs

Preoperative OHS did not differ between fracture and matched groups (mean 19.9 Vs 18.3,

p=0.496, Table 2, Figure 7) and postoperatively both displayed significant improvements

(p=0.002, repeated measure ANOVA, Figure 7). OHS was significantly worse in the fracture

group at both 1 year (35.7±9.2 Vs 40.2±9.0, p=0.026, Mann Whitney U test) and long term

follow up (33.6±13.8 Vs 40.9±9.2, p=0.008, Mann Whitney U test). There was no significant

difference in EQ-5D health or pain parameters between groups (Table 2). Long term

satisfaction was significantly worse in the fracture group (11% (3/28) dissatisfied Vs 0/102,

p<0.001, Chi squared).

Discussion

This study found good long term survival of 92% at 10 years and 85% at 15 years, with

revision as an endpoint, in patients who underwent cemented THR for late complications of

acetabular fracture. Compared to THR for other indications in age and sex matched patients,

long term patient reported outcomes were significantly worse. This may reflect the

technically challenging nature of THR surgery following acetabular fracture, the increased

likelihood of leg length discrepancies of >10mm and higher complications rates particularly

HO (35%), infection (6%) and dislocation (6%). Despite this, long term patient satisfaction

with THR following acetabular fracture was 89%.

Our 10 year THR survival compares favourably with the literature: 70-87% for uncemented

acetabular components; and 81% for cemented components [6, 7]. Our study adds to the

evidence supporting the use of cemented implants in this context. Aseptic loosening was not

problematic: 2/6 revisions performed for this indication with two further cases of radiographic

loosening. THR survival was best in patients who had non-operative management of their

initial fracture, where THR was performed within 1 year of fracture and in those under 55.

This was not significant however. Cemented THR provides a durable alternative to

uncemented THR to treat the late complications of acetabular fracture.

Our rates of dislocation, infection, and heterotopic ossification are comparable to those

previously reported for THR following acetabular fracture: dislocation 29/654 (4.5%) infection

37/654 (6%), and HO 196/654 (30%) [6]. In common with Morison et al [7], although overall

HO rates were high, the more severe variants of HO (Brooker grade 3 or 4) with the potential

to affect outcome [16] remained uncommon. Grade 4 HO following THR was preceded by

HO following fracture. Prophylaxis should be targeted at these patients [17].

Our comparison group of “standard” THRs was matched only for sex and age. This does not

take into account patient comorbidities or other musculoskeletal complaints which may be

suffered by patients who previously sustained high energy injuries. This element of the study

provides information for counselling patients undergoing THR following acetabular fracture:

they are twice as likely to suffer a complication, 2.5 times more likely to dislocate their THR

and 3.5 times as likely to have ectopic bone as patients undergoing THR for other

indications. In order to provide an age and sex matched cohort, young patients were

required who often have significant comorbidities or complex hip histories and indications.

Patients with AVN and osteoarthritis following Perthes disease, slipped femoral epiphysis

and developmental dysplasia (without dislocation), were included in addition to primary

osteoarthritis, reflecting the more varied indications for THR among young patients. The rate

of deep infection in the matched cohort was higher than expected. For all THRs performed in

our department, infection within 1 year is consistently below 1% [18]. It should be noted that

2 of the 4 matched patients with infection had significant comorbidities and risk factors for

infection [19] (diabetes, super-obesity, liver dysfunction with cirrhosis), and one had late

haematogenous spread from a defined source.

Differences in OHS between fracture and non-fracture cohorts at long-term follow up may

simply reflect the longer duration of follow-up in the fracture cohort. In common with Makridis

[6] we found fracture type and previous ORIF had no significant effect on THR outcome.

Posterior wall fractures and those involving the posterior column were disproportionately

represented, consistent with Briffa et al [3] who identify these fracture patterns as risk factors

for late THR. The earlier requirement for THR in patients >45 years may reflect the

increased incidence of AVN or PTOA with protrusio in older patients.

When considering THR in patients with previous acetabular fracture it is important to rule out

infection with serial CRPs and hip aspiration if ORIF has previously been performed.

Metalwork should be removed and THR postponed in confirmed infections, hence our mean

delay to THR of 8 years in infected cases. Leg length discrepancies should be assessed with

Hip-Knee-Ankle radiographs. Cross sectional imaging should be used to identify bone

defects, areas of non-union, areas of heterotopic bone, and intra-articular/peri-articular

metalwork requiring removal. Examination of both patient and notes is important to

determine previous surgical approaches. Most ORIF procedures are performed via a

Kocher-Langenbeck approach and thus a posterior approach can be used at THR, paying

particular attention to distorted anatomy, especially shortening and protrusio which affect

subcutaneous landmarks. Scarring necessitates that external rotators and capsule are

dissected en-bloc with care to protect the sciatic nerve. The extent of leg length restoration

must also consider the nerve. Anterolateral or posterior approaches can be used at THR if

ORIF was performed via an anterior type approach. However, if metalwork was inserted via

an ilioinguinal or Stoppa type approach, it must be removed as a staged procedure via the

same approach – it will be inaccessible posteriorly. The contralateral limb must be palpable

intraoperatively to assess leg lengths. Revision type exposures including extensive proximal

femoral exposure and iliopsias release are often required. The true floor of the acetabulum is

identified to ensure accurate socket placement. Bone defects, present in 15/51 (30%) of

cases here, require management with bone graft or trabecular metal. Retained metalwork,

pelvic defects and deformities and leg length discrepancies make restoration of normal

anatomy and biomechanics difficult, as quantified in our radiographic analysis. If periarticular

metalwork is anticipated, a diamond burr should be available for removal of selected screws,

or parts thereof protruding into the prepared socket. If metalwork is neither infected nor

obstructive it can be left in-situ.

Limitations of this study include sample size and its retrospective nature. This is a

consequence of the rarity of both the fracture and the subsequent requirement for THR. This

study is one of the largest reported on THR following acetabular fracture and is the largest

examining modern cemented THR. Radiographs did not include calibration measures and

thus relative rather than absolute measurements have been reported. Though survival has

previously been compared between fracture and non-fracture patients, validated patient

reported outcomes have not to our knowledge. We matched for age and sex to limit the

confounding influence of these variables on outcomes, however both THR cohorts have

other features important in determining outcome which have not been considered in our

matching. This may have underestimated some differences that would become apparent

compared to a cohort of THR for primary osteoarthritis only.

Conclusions

Following acetabular fracture, patients with AVN or PTOA with protrusio require THR sooner

than those with PTOA. Patients over 45 years typically come to THR 2 years after fracture,

but considerable variation in timing is found in younger patients. When performed following

acetabular fracture, complications of THR are higher and patient reported outcomes inferior

to THR performed for other indications. Despite this a ten year survival of 92% confirms that

cemented THR is a durable option for managing these complex patients.

Table 1. Modes of failure necessitating THR. Mean (SD, range), * ANOVA.

Mode of Failure n Age at fracture (years)

p-value Time to THR (years) p-value

AVN femoral head 12 56.5 (16.3, 26-87) 0.008 2.2 (3.1, 0.2-11) 0.031PTOA 27 44.0 (17.6, 17-76) 9.4 (8.6, 0.4-25)PTOA with protrusio 4 72.3 (11.8, 54-81) 2.2 (3.5, 0.3-7.5)Post infection of ORIF 3 40.4 (26.3, 24-70) 8.0 (6.3, 1-13)Unknown 5

Table 2. Outcome of THR following acetabular fracture compared to the matched cohort.

Mean (SD, range), number [%].^ = Fisher’s exact, †= unpaired T-test, *Mann-Whitney U, ** Chi squared

Post Fracture (n=51)

Match(n=102)

p-value

Age at THR 57.4 (15.6, 25-87) 55.6 (14.6, 17-81) 0.463†Male 34 [67] 70 [70] 0.806**Length of follow up (yrs)

9.1 (6.5, 0.5 - 23) 7.6 (2.0, 4-10) 0.055*

Approach Anterolateral 12 [24] 35 [34] <0.001Posterior 34 [67] 67 [66]Unknown 5 [10] 0

Implants Augment 3 [6] 3 [3] 0.675**Bearing MOP 46 [90] 57 [56]

COP 5 [10] 45 [44]

ComplicationsEarly Infection 1 [2] 0 0.009**

Dislocation 1 [2] 0Death 1 [2] 0

Late Deep infection 2 [4] 4 [4] 0.056**Dislocation 2 [4] 1 [1]

Aseptic loosening 4 [8] 1 [1}Periprosthetic

fracture1 [2] 2 [2]

Psoas bursitis 1 [2] 1 [1]Ceramic head

fracture0 1 [1]

Heterotopic ossification

Grade 1 11 [22] 4 [4] <0.001**Grade 2 4 [8] 4 [4]Grade 3 1 [2] 1 [1]Grade 4 2 [4] 0

PROMsOHS Pre-op 19.9 (10.4, 5-36) 18.3 (7.8, 3-48) 0.496†

1 year 35.7 (9.2, 17-48) 40.2 (9.0, 12-48) 0.026*Long term 33.6 (13.8, 3-48) 40.9 (9.2, 15-48) 0.008*

Long term EQ-5D Pain 74.2 (20.7, 20-98) 75.5 (31.7, 0-100) 0.936†Health 75.6 (19.3, 25-100) 79.4 (20.3, 24-100) 0.415†

Long term satisfaction Very satisfied 12 [43] 83 [84] <0.001**Satisfied 13 [46] 7 [7]Uncertain 0 10 [10]Dissatisfied 1 [4] 0Very dissatisfied 2 [7] 0

Table 3. Revisions of THR performed following acetabular fracture.

Survival (years) Sex Age at

THRAge at fracture Stem Bearing Mechanism of Failure

5.9 M 55.93 54.93 Exeter MOP Infection8.4 M 53.08 48.81 Exeter MOP Dislocation

13.8 F 68.07 68.07 Unknown cemented MOP Infection

20.0 M 39.54 38.45 Exeter MOP Aseptic loosening of acetabulum

21.8 F 28.37 25.36 Unknown cemented MOP Aseptic loosening of acetabulum

23.0 M 63.33 60.33 Exeter MOP Dislocation secondary to wear

Table 4. Subgroup analyses of THR outcomes (OHS and survival) within the post-acetabular

fracture group: ORIF Vs non-operative fracture management; early (< 1 year) Vs late (>1

year) THR; and younger (<55 years) Vs older (>55 years) patients at fracture.

Mean (SD, range), * Mann Whitney U Test, ^ Log rank.

Subgroup Oxford Hip Score 10 year survival (95% CI)

n 1 year Long term

Fracture management

ORIF 21 34.7 (9.8, 17-47) 32.4 (14.9, 3-48) 90.9% (78.7 to 100)

Non-operative

8 37.2 (8.7, 22-48) 36.9 (10.6,16-48) 100%

p value 0.607* 0.649* 0.450^

THR timing <1 year 6 31.0 (9.3, 17-41) 31.2 (14.7, 3-43) 92.3% (77.8 to 100)

>1 year 23 38.8 (8.1, 24-48) 34.3 (13.8, 5-48) 91.7% (76.0 to 100)

p value 0.145* 0.414* 0.569^

Age at fracture <55 years 17 37.8 (8.8, 24-47) 37.8 (12.5, 5-48) 88.9% (68.3 to 100)

>55 years 12 34.2 (9.6, 17-48) 30.4 (12.5, 3-48) 82.1% (59.2 to 100)

p value 0.478* 0.061* 0.103^

References

1. Giannoudis, P.V., et al., Operative treatment of displaced fractures of the acetabulum. A meta-analysis. J Bone Joint Surg Br, 2005. 87(1): p. 2-9.

2. Daurka, J.S., et al., Acetabular fractures in patients aged > 55 years: a systematic review of the literature. Bone Joint J, 2014. 96-B(2): p. 157-63.

3. Briffa, N., et al., Outcomes of acetabular fracture fixation with ten years' follow-up. J Bone Joint Surg Br, 2011. 93(2): p. 229-36.

4. Romness, D.W. and D.G. Lewallen, Total hip arthroplasty after fracture of the acetabulum. Long-term results. J Bone Joint Surg Br, 1990. 72(5): p. 761-4.

5. Berry, D.J. and M. Halasy, Uncemented acetabular components for arthritis after acetabular fracture. Clin Orthop Relat Res, 2002(405): p. 164-7.

6. Makridis, K.G., et al., Total hip arthroplasty after acetabular fracture: incidence of complications, reoperation rates and functional outcomes: evidence today. J Arthroplasty, 2014. 29(10): p. 1983-90.

7. Morison, Z., et al., Total Hip Arthroplasty After Acetabular Fracture Is Associated With Lower Survivorship and More Complications. Clin Orthop Relat Res, 2016. 474(2): p. 392-8.

8. Sierra, R.J., et al., Acetabular fractures: the role of total hip replacement. Bone Joint J, 2013. 95-B(11 Suppl A): p. 11-6.

9. Letournel, E., Acetabulum fractures: classification and management. Clin Orthop Relat Res, 1980(151): p. 81-106.

10. Brooker, A.F., et al., Ectopic ossification following total hip replacement. Incidence and a method of classification. J Bone Joint Surg Am, 1973. 55(8): p. 1629-32.

11. Mahmood, S.S., et al., Validity, reliability and reproducibility of plain radiographic measurements after total hip arthroplasty. Skeletal Radiol, 2015. 44(3): p. 345-51.

12. Gruen, T.A., G.M. McNeice, and H.C. Amstutz, "Modes of failure" of cemented stem-type femoral components: a radiographic analysis of loosening. Clin Orthop Relat Res, 1979(141): p. 17-27.

13. DeLee, J.G. and J. Charnley, Radiological demarcation of cemented sockets in total hip replacement. Clin Orthop Relat Res, 1976(121): p. 20-32.

14. Dawson, J., et al., QUESTIONNAIRE ON THE PERCEPTIONS OF PATIENTS ABOUT TOTAL HIP REPLACEMENT. Journal of Bone &amp; Joint Surgery, British Volume, 1996. 78-B(2): p. 185-190.

15. Hurst, N.P., et al., Validity of Euroqol--a generic health status instrument--in patients with rheumatoid arthritis. Economic and Health Outcomes Research Group. Br J Rheumatol, 1994. 33(7): p. 655-62.

16. Kocic, M., et al., Clinical significance of the heterotopic ossification after total hip arthroplasty. Orthopedics, 2010. 33(1): p. 16.

17. Vavken, P., L. Castellani, and T.P. Sculco, Prophylaxis of heterotopic ossification of the hip: systematic review and meta-analysis. Clin Orthop Relat Res, 2009. 467(12): p. 3283-9.

18. None-listed. Scottish Arthroplasty Project Biennial Report 2016. 2016 [cited 2016 15th November 2016].

19. Kunutsor, S.K., et al., Patient-Related Risk Factors for Periprosthetic Joint Infection after Total Joint Arthroplasty: A Systematic Review and Meta-Analysis. PLoS One, 2016. 11(3): p. e0150866.