Reduced cervical spine canal AP diameter is linked to the development of spinal cord injury and myelopathy. This is of particular interest to clinicians in New Zealand, given a unique socio-ethnic make-up and prevalent participation in collision sport. Our study builds upon previous unpublished evidence, by analysing normal cervical spine CT scans to explore morphological differences in the sub-axial cervical spine canal, between New Zealand European, Māori and Paciāca individuals.

670 sub-axial cervical vertebrae (C3-C7) were analysed radiographically using high resolution CT trauma scans, showing no acute pathology with respect to the cervical spine. All measurements were made uPlising mulP-planar reconstruction software to obtain slices parallel to the superior endplate at each vertebral level. Maximal canal diameter was measured in the AP and transverse planes. Statistical analysis was performed using analysis of variance (ANOVA).

We included 250 Maori, 250 NZ European and 170 Paciāca vertebrae (455 male, 215 female). Statistically and clinically signiācant differences were found in sagittal canal diameter between all ethnicities, at all spinal levels. NZ European vertebrae demonstrated the largest AP diameter and Paciāca the smallest, at all levels. Transverse canal diameter showed no signiācant difference between ethnicities, however the raatio of AP:transverse diameter was signiācantly different at all spinal levels except C3. Subjective morphological differences in the shape of the vertebral canal were noted, with Māori and Paciāca patients tending towards a flatter, curved canal shape.

A previous study of 166 patients (Coldham, G. et al. 2006) found cervical canal AP diameter to be narrower in Māori and Paciāca patients than in NZ Europeans. Our study, evaluating the normal population, conārms these differences are likely reflecPve of genuine variation between these ethniciPes. Future research is required to critically evaluate the morphologic differences noted during this study.

Introduction

The accuracy of hexapod circular external fixator deformity correction is contingent on the precision of radiographic analysis during the planning stage. The aim of this study was to compare the SMART TSF (Smith and Nephew, Memphis, Tennessee) in-suite radiographic analysis methods with the traditional manual deformity analysis methods in terms of accuracy of correction.

Introduction and Objective

Interest for direct anterior approach (DAA) in hip hemiarthroplasty (HHA) has greatly increased in recent years, however which is the best surgical approach in hip replacement treating femoral neck fractures (FNFs) is already unclear. The aim of this study is to perform a radiographic and perioperative complications analysis by comparing the direct anterior approach (DAA) with the direct lateral approach (DLA) in patients treated with hemiarthroplasty for FNFs.

Introduction: The knee joint in congenital longitudinal deformities of the lower extremity shows a large variety of pathological findings. Valgus deformity is found in most cases and is described as being juxta- articular. To describe the true anatomic pathology we performed a radiographic analysis of the knee joint in congenital longitudinal deformities.

Patients and Method: Between 1985 and 2001 we treated 102 patients presenting with congenital longitudinal deformities. Inclusion criteria for this study were diagnoses of fibular hemimelia (FBH) and/or congenital femoral deficiency (CFD), an age between 5 and 16 years, unilateral affection and availability of long standing X-rays, whereas bilateral affection or previous operations on the lower extremities were defined as exclusion criteria. Twenty-four parameters were defined on the femur and tibia respectively and a nomenclature was created. The mean values including standard deviation were calculated and we statistically compared the parameters of the affected to those of the non-affected knee. Furthermore, MRI scans of the knee joint of 20 of these patients were evaluated.

Results: Thirty- nine patients (19 female, 20 male) met the inclusion criteria. The average age at the time of evaluation was 8.87 years (3.1 SD). A combined deficiency of femur and tibia was found in 35 patients. The predominant diagnosis was CFD in 13, fibular hemime-lia in 13 and fibular aplasia in 9 cases. The anatomic lateral distal femoral angle (ALDFA) measured 75.4° (2.5 SD) on the affected, and 81.6° (1.6 SD) on the non-affected knee. The lateral distal femoral metaphyseal angle of the affected side and of the non-affected side showed no significant difference. The distal lateral femoral epiphyseal width (DLFEW) was decreased in the affected limb compared to the non affected limb, whereas the distal medial femoral epiphyseal width (DMFEW) of the affected and non-affected side showed only a minor difference. In the tibia we found no significant difference between the variables for the medial proximal tibial angle (MPTA) and for the medial proximal tibial metaphyseal angle (MPTMA) of the affected and the non-affected limb. A significant difference was found between the proximal lateral tibial epiphyseal width of the affected and the non-affected side. Analysis of the MRI scans revealed aplasia of the anterior cruciate ligament in 18 cases and aplasia of the posterior cruciate ligament in 8 of the 20 cases. The defect of ossification of the lateral tibial epiphysis as seen in plain X-rays is visible in the MRI scans as cartilage anlage. (Only the most important findings are summarized)

Conclusions: In our patient population only four patients had FBH or CFD but 35 cases presented combined defects; we assume that the femur is affected to some extent in almost all cases of FBH. The hypoplasia was only found in the lateral aspects of femur and tibia and was primarily located within the femoral epiphysis. The metaphysis was not or only minimally affected in the evaluated longitudinal deficiencies. Awareness of sagittal instability, due to ACL and/or PCL aplasia, is necessary to avoid subluxation or dislocation when lengthening procedures are performed.

Sectioned femoral components retrieved from failed hip resurfacing arthroplasties show resorption of proximal femoral bone or formation of a fibrous membrane at the bone cement interface. Our study uses Finite Element Analysis (FEA) to examine the effects of the implant orientation on bone remodelling following hip resurfacing arthroplasty. A radiographic analysis of the proximal femur following hip resurfacing was conducted in order to draw a comparison to the FEA findings.

A 3D FEA model of the Birmingham Hip Resurfacing (BHR) was created based on the geometry and material properties of a 45 year-old female donor hip. Hip joint and muscle loads were applied. Bone remodelling stimuli was determined using changes in strain energy. A range of implant orientations were compared to study the affect on bone remodelling. A retrospective radiological analysis was undertaken on 100 hips with a minimum of 5 years follow up. Femoral neck diameter was measured at post-op, 2 and 5 years, as well as neck and stem shaft angles.

FEA showed that valgus orientation was associated with increased resorption underneath the shell. Varus orientation showed increased bone formation at the stem tip. The radiological analysis identified 2 distinct patterns of neck thinning. Slow thinners (76%) had < 5% reduction in neck diameter at 2 years and < 10% at 5 years. Rapid thinner (24%) had > 5% thinning at 2 years and > 10% at 5 years. The mean percentage reduction in neck diameter was significantly different between the two groups at the two time points (p< 0.01). The rapid group had a higher proportion of valgus aligned implants (88%) and a significant decrease in reconstructed offset (p=0.0023).

The FEA results have shown that stem alignment can affect bone resorption resurfacing. FEA results were consistent with the radiological findings. Additional retrieval studies are necessary to help understand aetiology of implant failures.

Introduction: Sectioned femoral components retrieved from failed hip resurfacing arthroplasties show resorption of proximal femoral bone or formation of a fibrous membrane at the bone cement interface, in a proportion of cases. We hypothesize that both scenarios create a functional discontinuity zone (FDZ), which exacerbates offloading the proximal bone and promoting resorption. Our study uses finite element modeling to examine the effects of the presence of an FDZ on bone remodeling following hip resurfacing arthroplasty. A radiographic analysis of the proximal femur following hip resurfacing was also conducted in order to draw a comparison to clinical findings.

Methods: The hip resurfacing FE models were oriented in 3 distinct stem-shaft angles: 136 ‘neutral’, 120 ‘varus’ and 150 ‘valgus’. A low-modulus (2 MPa) FDZ (approx. 2 mm thick) was simulated beneath the implant head. Femoral joint and muscle loads were applied to simulate peak joint loading during gait. Interface stress was compared for the normal and simulated FDZ resurfaced femurs. Bone remodeling stimuli was determined using changes in strain energy. A retrospective radiological analysis was undertaken on 98 hips (74 males and 24 females) with a minimum of 5 years follow up. Measurements of the prosthesis-shaft angle, pre–and post-operative femoral head offset and femoral neck diameter at 2 and 5 years were undertaken.

Results: The presence of the simulated FDZ in the FE analysis resulted in increased proximal-medial bone resorption and slightly greater bone formation surrounding the stem. Correspondingly, device-bone interface stresses were found to decrease proximally under the loading platform and increase at the stem, particularly adjacent to the stem-head junction. The valgus BHR femur led to increased resorption, especially around the periphery of the neck and on the medial side. The radiological analysis identified 2 groups; 22 hips (Group 1) had a mean 5.61mm (sd 2.07) reduction in neck diameter over 5 years and 76 hips (Group 2) demonstrated slow reduction in neck diameter, mean 1.13mm (sd 0.97). Neck thinning at 2 and 5 years was significantly greater for Group 1 (p< 0.0001). Group 1 hips had significantly greater reduction in femoral offset (p=0.041), with greater valgus angle oriented components (p=0.09). Reduction in femoral offset was significantly associated with greater valgus orientations (p< 0.0001). The Group 1 revision rate was 36.4% compared to 2.6% in Group 2 (p< 0.0001).

Discussion: The FE results support the hypothesis that the presence of a FDZ decreases load transfer to the proximal bone, resulting in increased medial stress shielding and resorption. These results are consistent with the Group 1 clinical findings. In order to better understand the cause of implant failures in hip resurfacing arthroplasty, additional retrieval studies are necessary.

Tear pattern and tendon involvement are risk factors for the development of a pseudoparalytic shoulder. However, some patients have similar tendon involvement but significantly different active forward flexion. In these cases, it remains unclear why some patients suffer from pseudoparalysis and others with the same tear pattern show good active range of motion. Moment arms (MA) and force vectors of the RC and the deltoid muscle play an important role in the muscular equilibrium to stabilize the glenohumeral joint. Biomechanical and clinical analyses were conducted calculating different MA-ratios of the RC and the deltoid muscle using computer rigid body simulation and a retrospective radiographic investigation of two cohorts with and without pseudoparalysis and massive RC tears. Idealized MAs were represented by two spheres concentric to the joints centre of rotation either spanning to the humeral head or deltoid origin of the acromion. Individual ratios of the RC /deltoid MAs on antero-posterior radiographs using the newly introduced Shoulder Abduction Moment (SAM) Index was compared between the pseudoparalytic and non-pseudoparalytic patients.

Decrease of RC activity and improved glenohumeral stability (+14%) was found in simulations for MA ratios with larger diameters of the humeral head which also were consequently beneficial for the (remaining) RC. Clinical investigation of the MA-ratio showed significant risk of having pseudoparalysis in patients with massive tears and a SAM Index <0.77 (OR=11). The SAM index, representing individual biomechanical characteristics of shoulder morphology has an impact on the presence or absence of pseudoparalysis in shoulders with massive RC tears.

Purpose

Degenerative changes of the lumbar motion segment often lead to stenosis of the spinal canal or neuroforamen. Axial lumbar interbody fusion (AxiaLIF) is intended to indirectly increase and stabilize foraminal dimensions by restoring disc height in patients with degenerative disc disease, thereby relieving axial and radicular pain. Therefore, this study investigated the effects of AxiaLIF on anterior disc height, posterior disc height, foraminal height and foraminal width as well as to determine the effectiveness of this minimally-invasive technique for indirect decompression and restoration of disc height.

Aims

Patients with abnormal spinopelvic mobility are at increased risk for instability. Measuring the change in sacral slope (ΔSS) can help determine spinopelvic mobility preoperatively. Sacral slope (SS) should decrease at least 10° to demonstrate adequate posterior pelvic tilt. There is potential for different ΔSS measurements in the same patient based on sitting posture. The purpose of this study was to determine the effect of sitting posture on the ΔSS in patients undergoing total hip arthroplasty (THA).

INTRODUCTION: Atlanto-axial instability due to Rheumatoid arthritis has been treated by posterior C1/C2 wiring techniques supplemented with bone graft. Magerls technique of Transarticular fixation provides a three-point fixation by eliminating motion, promoting fusion, increased mechanical strength and treating instability. It allows fixation across the plane of movement and prevents basilar invagination.

The clinical results of transarticular fixation are satisfactory in terms of clinical outcome with few complications. However there are concerns that these patients develop subaxial kyphosis. It is important to highlight that none of these patients in our series had supplementary wiring techniques with TAS The purpose of this study is to analyse postoperative Xrays of patients who have undergone transarticular atlantoaxial fixation and look at the following parameters;

What percentage of patients develop subaxial kyphosis?

MATERIALS & METHODS: 15 patients underwent pre and postoperative cervical spine X-rays in the AP and lateral projections. In addition flexion/extension views were also obtained pre and postoperatively.

We analysed the following parmeters:

Pre and Postoperative ADI and PADI.

It is important to highlight that all these 15 patients had bony fusion at the C1/C2 joints and these findings have been analysed and published in the clinical counterpart of this study (Fusion rates 97% in 36/37 patients).

RESULTS: As highlighted, the clinical outcome of these patients has been published. We would like to present the radiological parameters of this subgroup of patients. The ADI improved in 13 patients with a preoperative median of 7 and postoperatively 3.5. The preoperative and postoperative PADI remained at 15. The C0/C1 angle changed from 12 to 17 postoperatively. The C2/C7 angle changed from 21 to 26 postoperatively. C1/C7 angle changed from 39 to 41. The spinal cord diameter remained at 15 pre and postoperatively.

There was only 1 patient with C2/C3 slip on flexion/extension views. 2 patients developed subaxial kyphosis with evidence of significant disc degeneration on preoperative imaging.

There are some interesting conclusions from these 15 xrays.

Only 2 out of 13 patients have developed a subaxial kyphosis.

From 1993 to 2008, 44 DELTA III prostheses were implanted for 33 three-part and four-part displacements and 11 fracture-dislocations, in 3 males for 41 females, with an average age of seventy five years. The results were estimated with AP and profile X-rays.

Ten patients died and and three moved. Thirty one cases were reviewed with a mean follow-up of 6.3 years, range 1 to 15. The radiographs showed:

two 2-mm thick borders on the glenoid at four and eight years.

In elderly patients with trauma, when attachment of the tubercles on the classical orthopaedics devices is impossible, the use of a RSA leads to precocious worrying and progressive images but with only one re-intervention for an aseptic loosening of the base plate at a twelve year evolution. New developments in design and bearing surfaces, new surgical techniques of implantation and a more long term results will probably provide more durable utilization of the reverse concept for this indication.

Synthesis and hemi-prosthesis give well known radiological results for acute proximal complex humeral fractures in elderly population. We wanted to expose the radiological outcome of the reverse concept in this indication.

From 1993 to 2007, forty one DELTA III were implanted for thirty two three-part and four-part displacements and nine fracture-dislocations, in 3 males for 38 females, with an average age of seventy five years. The results were estimated with AP and LAMY profile X-rays.

Because of nine deceases and two moving, thirty cases were reviewed with a mean follow-up of 6.5 years, range 1 to 14. The radiographs showed: two 2-mm thick borders on the glenoid at four and eight years with a scapular notch at 11 years and an aseptic loosening of the base plate at 12 years with a broken polar inferior screw. The patient underwent an easy surgical revision because of a fair bone stock. There was no wear of the polyethylene. According to the NEROT classification, seventeen inferior scapular notches were observed with a mean occurrence time of 4.7 years. The seven type-1 notches appeared at a mean of 2 years and the five type-2 notches at a mean of 4.3 years. We observed three type-3 notches which reached the inferior screw at 5,6 and 7 years, and two type-4 notches which extended beyond the inferior screw at 6 and 7 years follow-up, respectively. There seem to be two distinct patters of notches: mechanical, stable proximal humeral bone loss because of an impingement between the humeral component and the inferior scapular pillar and biological, progressive in size, evolving over time with proximal humeral bone loss because of polyethylene disease; the longer the follow-up, the more severe the notch. Fourteen inferior spurs, stable after emergence, were reported with a mean occurrence time of 2.5 years range 1 to 6 years. One joint ossification occurred at 6 months and was stable at 6 year follow-up. The humeral results consisted in four medial (5,6,7 and 10 years) proximal bone looses and two bone-cement interface medial borders on the two thirds of the height of the stem at 5 year follow-up. In these six cases, there was a notch associated. We reported one case of septic humeral loosening at 2 year follow-up.

For acute proximal humeral complex fractures in elderly population, when re-fixation of the tubercles on the classical orthopaedics devices is impossible, the use of a DELTA III prosthesis shows, with a mean follow-up of 6.5 years, worrying images in 70% of the cases. These images are on the glenoid in 70% of the cases, appeared before seven years in 86% and are progressive in 50% of the cases. But, we have only one re-intervention for an aseptic loosening of the base plate at a twelve year evolution. New developments in design and bearing surfaces and a more long term results will probably provide more durable utilization of the reverse concept in this indication.

Radiographic evidence of migration of the femoral stem component after THA is the most important diagnostic sign of femoral implant loosening. Early detection of stem subsidence may help in deciding to perform revision surgery before severe bone destruction has occurred, at a moment when standard clinical and radiological follow-up may still be reassuring.

The aim of this study was to identify the most appropriate bone and prosthetic landmarks to study subsidence and to determine the accuracy of the Imagika® method as compared to the ‘gold standard’ EBRA-FCA® software.

256 THA in 242 patients (102 men, 140 women) with a median age of 63.8 years (range: 36–85) received 4 different cementless or cemented prosthetic stem designs. They were followed for 10.6 years (range: 6–16). CLS® stems were used in 56 patients, MS-30® in 76, Elite® in 50 and Osteal® in 74.

4 specific analysis models were created in the Imagika® software in order to evaluate several possible landmarks on the proximal femur and on the stem, and to evaluate the possibility of using a correction factor to improve the comparability of successive x-rays taken under non standardised conditions. The most accurate prosthetic landmarks were the prosthesis shoulder in CLS® and MS-30® stems and the lateral aspect of the collar in Elite® and Osteal® stems. The best bone landmark was the top of the greater trochanter in all cases.

For the whole series, the annual linear subsidence rates were 0.049+/−0.014 mm with EBRA-FCA® and 0.052+/−0.012 mm with Imagika® respectively (P = 9E-7). Migration values in the 4 different groups were respectively 0.06 +/− 0.01 mm/yr and 0.05 +/− 0.01 mm/yr in the CLS® group (P = 4.6E-6), 0.02 +/− 0.002 mm/yr and 0.06 +/− 0.09 mm/yr in the MS-30® group (P = 6.8E-4), 0.06 +/− 0.002 mm/yr and 0.04 +/− 0.003 mm/yr in the Elite® group (P = 4.2E-5), and 0.05 +/− 0.005 mm/yr and 0.06 +/− 0.004 mm/yr in the Osteal® group (P = 7.4E-7). The different prosthetic designs did not show significant differences concerning migration values when studied according both methods.

Thanks to a correction factor, the Imagika® method uses all the radiographs when EBRA-FCA® rejects incomparable radiographs.

The Imagika® method is more users friendly and provides excellent reliability thanks to an automatic edge detection device.

Since no significant difference was observed between EBRA-FCA® and Imagika® methods whatever the prosthetic stem design studied, our results authorise us to apply these analysis models within the Imagika® software to all THAs to follow their radiographic evolution and to possibly predict the clinical evolution.

This study provides recommendations on the position of the implant in reverse shoulder replacement in order to minimise scapular notching and osteophyte formation. Radiographs from 151 patients who underwent primary reverse shoulder replacement with a single prosthesis were analysed at a mean follow-up of 28.3 months (24 to 44) for notching, osteophytes, the position of the glenoid baseplate, the overhang of the glenosphere, and the prosthesis scapular neck angle (PSNA).

A total of 20 patients (13.2%) had a notch (16 Grade 1 and four Grade 2) and 47 (31.1%) had an osteophyte. In patients without either notching or an osteophyte the baseplate was found to be positioned lower on the glenoid, with greater overhang of the glenosphere and a lower PSNA than those with notching and an osteophyte. Female patients had a higher rate of notching than males (13.3% vs 13.0%) but a lower rate of osteophyte formation (22.9% vs 50.0%), even though the baseplate was positioned significantly lower on the glenoid in females (p = 0.009) and each had a similar mean overhang of the glenosphere.

Based on these findings we make recommendations on the placement of the implant in both male and female patients to avoid notching and osteophyte formation.

Cite this article: Bone Joint J 2013;95-B:530–5.

INTRODUCTION AND OBJECTIVE: To compare the clinical and radiological results of the unilateral posterolateral approach with the bilateral transpedicular approach in the treatment of osteoporotic fractures with percutaneous vertebroplasty (PV).

MATERIAL AND METHODS: 75 patients with 113 symptomatic osteoporotic vertebral fractures treated with PV were studied: 53 females and 22 males. Average age 70.5 years (41 – 91), average follow-up 24 months (12 – 50). A unilateral posterolateral approach was used in 84 vertebrae and a bilateral transpedicular approach in 29 vertebrae. The most frequently treated vertebrae were L1 (30 vertebrae), L2 (27), L3 (19) and D12 (14). A posterolateral approach was used in 63 vertebrae (80.8%) and a transpedicular bilateral approach in 15 (19.2%). X-ray and MRI at pre-op, post-op, three months, six months and annually; post-op C-T of all patients. The Visual Analogical Scale (VAS), and the Oswestry Disability Index (ODI)were used at pre-op and six month follow-up.

RESULTS: There were 72 cement leakages in 54 vertebrae (47.8%). In the posterolateral approach there were 33 cement leakages (39.3%), and there were 21 vertebrae with cement leaks (72.4%) in the bilateral transpedicular approach group. This difference is statistically significant (p=0.004). The cement leakages were classified in six anatomic groups. For the whole series cement leakages were more frequent to the proximal disk with 22 cases (19.5%), 11 leaks to the distal disk (9.7%), 9 to the external-vertebral venous plexus (8%), 10 paraparavertebral leaks (8.8%), 8 spinal canal leaks (7.1%), others 4 cases (3.5%) The most frequent cement leakage in both approaches is to the proximal disk. In the posterolateral approach the pre-op and post-op VAS were 7.76 and 2.66 as well as a pre-op and post-op ODI of 72 and 32.73. In the transpedicular approach the pre-op and post-op VAS were 7.71 and 2.21, and ODI of 66.3 and 28.04 respectively. No statistically significant differences were found in the clinical results between both groups.

CONCLUSION: The clinical outcomes for both approaches were similar, however the incidence of cement leakages is significantly higher in the transpedicular approach. We recommend the unilateral posterolateral approach in the treatment of osteoporotic vertebral fractures with PV to reduce the risk of cement leakage.

Aims. To develop an early implant instability murine model and explore the use of intermittent parathyroid hormone (iPTH) treatment for initially unstable implants. Methods. 3D-printed titanium implants were inserted into an oversized drill-hole in the tibiae of C57Bl/6 mice (n = 54). After implantation, the mice were randomly divided into three treatment groups (phosphate buffered saline (PBS)-control, iPTH, and delayed iPTH). Radiological analysis, micro-CT (µCT), and biomechanical pull-out testing were performed to assess implant loosening, bone formation, and osseointegration. Peri-implant tissue formation and cellular composition were evaluated by histology. Results. iPTH reduced radiological signs of loosening and led to an increase in peri-implant bone formation over the course of four weeks (timepoints: one week, two weeks, and four weeks). Observational histological analysis shows that iPTH prohibits the progression of fibrosis. Delaying iPTH treatment until after onset of peri-implant fibrosis still resulted in enhanced osseointegration and implant stability. Despite initial instability, iPTH increased the mean pull-out strength of the implant from 8.41 N (SD 8.15) in the PBS-control group to 21.49 N (SD 10.45) and 23.68 N (SD 8.99) in the immediate and delayed iPTH groups, respectively. Immediate and delayed iPTH increased mean peri-implant bone volume fraction (BV/TV) to 0.46 (SD 0.07) and 0.34 (SD 0.10), respectively, compared to PBS-control mean BV/TV of 0.23 (SD 0.03) (PBS-control vs immediate iPTH, p < 0.001; PBS-control vs delayed iPTH, p = 0.048; immediate iPTH vs delayed iPTH, p = 0.111). Conclusion. iPTH treatment mediated successful osseointegration and increased bone mechanical strength, despite initial implant instability. Clinically, this suggests that initially unstable implants may be osseointegrated with iPTH treatment. Cite this article: Bone Joint Res 2022;11(5):260–269

Dual-mobility (DM) bearings are effective to mitigate dislocation in revision total hip arthroplasty (THA). However, data on its use for treating dislocation is scarce. Aim of this study was to compare DM bearings, standard bearings and constrained liner (CL) in revision THA for recurrent dislocation and to identify risk factors for re-dislocation. We reviewed 100 consecutive revision THAs performed for dislocation from 2012 and 2019. 45 hips (45%) received a DM construct, while 44 hips (44%) and 11 hips (11%) had a standard bearing and CL, respectively. Rates of re-dislocation, re-revision for dislocation and overall re-revision were compared. Radiographs were assessed for cup positioning, restoration of centre of rotation, leg length and offset. Risk factors for re-dislocation were determined by cox regression analysis. Modified Harris hip scores (mHHS) were calculated. Mean follow-up was 53 months (1 to 103). DM constructs were used more frequently in elderly patients (p=0.011) and hips with abductor deficiency (p< 0.001). The re-dislocation rate was 11.1% for DM bearings compared with 15.9% for standard bearings and 18.2% for CL (p=0.732). Revision-free survival for DM constructs was 83% (95% CI 0.77 – 0.90) compared to 75% (95% CI 0.68 – 0.82) for standard articulations and 71% (95% CI 0.56 – 0.85) for CL (p=0.455). Younger age (HR 0.91; p=0.020), lower comorbidity (HR 0.42; p=0.031), smaller heads (HR 0.80; p=0.041) and cup retention (HR 8.23; p=0.022) were associated with re-dislocation. Radiological analysis did not reveal a relationship between restoration of hip geometry and re-dislocation. mHHS significantly improved from 43.8 points to 65.7 points (p<0.001) with no differences among bearing types. Our findings suggest that DM bearings do not sufficiently prevent dislocation in revision THA for recurrent dislocation. Reconstruction of the abductor complex may play a key role to reduce the burden in these high-risk patients

Pelvic tilt can vary over time due to aging and the possible appearance of sagittal spine disorders. Cup position in total hip arthroplasty (THA) can be influenced due to these changes. We assessed the evolution of pelvic tilt and cup position after THA and the possible appearance of complications for a minimum follow-up of ten years. 343 patients received a THA between 2006 and 2009. All were diagnosed with primary osteoarthritis and their mean age was 63.3 years (range, 56 to 80). 168 were women and 175 men. 250 had no significant lumbar pathology, 76 had significant lumbar pathology and 16 had lumbar fusion. Radiological analysis included sacro-femoral-pubic (SFP), acetabular abduction (AA) and anteversion cup (AV) angles. Measurements were done pre-operatively and at 6 weeks, and at five and ten years post-operatively. Three measurements were recorded and the mean obtained at all intervals. All radiographs were evaluated by the same author, who was not involved in the surgery. There were nine dislocations: six were solved with closed reduction, and three required cup revision. All the mean angles changed over time; the SFP angle from 59.2º to 60º (p=0.249), the AA angle from 44.5º to 46.8º (p=0.218), and the AV angle from 14.7º to 16.2º (p=0.002). The SFP angle was lower in older patients at all intervals (p<0.001). The SFP angle changed from 63.8 to 60.4º in women and from 59.4º to 59.3º in men, from 58.6º to 59.6º (p=0.012). The SFP angle changed from 62.7º to 60.9º in patients without lumbar pathology, from 58.6º to 57.4º in patients with lumbar pathology, and from 57.0º to 56.4º in patients with a lumbar fusion (p=0.919). The SFP cup angle was higher in patients without lumbar pathology than in the other groups (p<0.001), however, it changed more than in patients with lumbar pathology or fusion at ten years after THA (p=0.04). Posterior pelvic tilt changed with aging, influencing the cup position in patients after a THA. Changes due to lumbar pathology could influence the appearance of complications long-term

Aims. The purpose of this study was to compare reoperation and revision rates of double plating (DP), single plating using a lateral locking plate (SP), or distal femoral arthroplasty (DFA) for the treatment of periprosthetic distal femur fractures (PDFFs). Methods. All patients with PDFF primarily treated with DP, SP, or DFA between 2008 and 2022 at a university teaching hospital were included in this retrospective cohort study. The primary outcome was revision surgery for failure following DP, SP, or DFA. Secondary outcome measures included any reoperation, length of hospital stay, and mortality. All basic demographic and relevant implant and injury details were collected. Radiological analysis included fracture classification and evaluation of metaphyseal and medial comminution. Results. A total of 111 PDFFs (111 patients, median age 82 years (interquartile range (IQR) 75 to 88), 86% female) with 32 (29%) Su classification 1, 37 (34%) Su 2, and 40 (37%) Su 3 fractures were included. The median follow-up was 2.5 years (IQR 1.2 to 5.0). DP, SP, and DFA were used in 15, 66, and 30 patients, respectively. Compared to SP, patients treated with DP were more likely to have metaphyseal comminution (47% vs 14%; p = 0.009), to be low fractures (47% vs 11%; p = 0.009), and to be anatomically reduced (100% vs 71%; p = 0.030). Patients selected for DFA displayed comparable amounts of medial/metaphyseal comminution as those who underwent DP. At a minimum follow-up of two years, revision surgery for failure was performed in 11 (9.9%) cases at a median of five months (IQR 2 to 9): 0 DP patients (0%), 9 SP (14%), and 2 DFA (6.7%) (p = 0.249). Conclusion. Using a strategy of DP fixation in fractures, where the fracture was low but there was enough distal bone to accommodate locking screws, and where there is metaphyseal comminution, resulted in equivalent survival free from revision or reoperation compared to DFA and SP fixation. Cite this article: Bone Jt Open 2024;5(6):489–498

Aims. The Coronal Plane Alignment of the Knee (CPAK) classification is a simple and comprehensive system for predicting pre-arthritic knee alignment. However, when the CPAK classification is applied in the Asian population, which is characterized by more varus and wider distribution in lower limb alignment, modifications in the boundaries of arithmetic hip-knee-ankle angle (aHKA) and joint line obliquity (JLO) should be considered. The purposes of this study were as follows: first, to propose a modified CPAK classification based on the actual joint line obliquity (aJLO) and wider range of aHKA in the Asian population; second, to test this classification in a cohort of Asians with healthy knees; third, to propose individualized alignment targets for different CPAK types in kinematically aligned (KA) total knee arthroplasty (TKA). Methods. The CPAK classification was modified by changing the neutral boundaries of aHKA to 0° ± 3° and using aJLO as a new variable. Radiological analysis of 214 healthy knees in 214 Asian individuals was used to assess the distribution and mean value of alignment angles of each phenotype among different classifications based on the coronal plane. Individualized alignment targets were set according to the mean lateral distal femoral angle (LDFA) and medial proximal tibial angle (MPTA) of different knee types. Results. A very high concentration, 191 from 214 individuals (89.3%), were found in knee types with apex distal JLO when the CPAK classification was applied in the Asian population. By using aJLO as a new variable, the high distribution percentage in knee types with apex distal JLO decreased to 125 from 214 individuals (58.4%). The most common types in order were Type II (n = 70; 32.7%), Type V (n = 55; 25.7%), and Type I (n = 46; 21.5%) in the modified CPAK classification. Conclusion. The modified CPAK classification corrected the uneven distribution when applying the CPAK classification in the Asian population. Setting individualized TKA alignment targets according to CPAK type may be a practical method to recreate optimal LDFA and MPTA in KA-TKA. Cite this article: Bone Jt Open 2022;3(3):211–217