Progressive collapsing foot deformity (PCFD) is a complex foot deformity with varying degrees of hindfoot valgus, forefoot abduction, forefoot varus, and collapse or hypermobility of the medial column. In its management, muscle and tendon balancing are important to address the deformity. Peroneus brevis is the primary evertor of the foot, and the strongest antagonist to the tibialis posterior. Moreover, peroneus longus is an important stabilizer of the medial column. To our knowledge, the role of peroneus brevis to peroneus longus tendon transfer in cases of PCFD has not been reported.

This study evaluates patient reported outcomes including pain scores and any associated surgical complications for patients with PCFD undergoing isolated peroneus brevis to longus tendon transfer and gastrocnemius recession.

Patients with symptomatic PCFD who had failed non-operative treatment, and underwent isolated soft tissue correction with peroneus brevis to longus tendon transfer and gastrocnemius recession were included. Procedures were performed by a single surgeon at a large University affiliated teaching hospital between January 1 2016 to March 31 2021. Patients younger than 18 years old, or undergoing surgical correction for PCFD which included osseous correction were excluded.

Patient demographics, medical comorbidities, procedures performed, and pre and post-operative patient related outcomes were collected via medical chart review and using the appropriate questionnaires.

Outcomes assessed included Visual Analogue Scale (VAS) for foot and ankle pain as well as sinus tarsi pain (0-10), patient reported outcomes on EQ-5D, and documented complications.

Statistical analysis was utilized to report change in VAS and EQ-5D outcomes using a paired t-test. Statistical significance was noted with p<0.05.

We analysed 43 feet in 39 adults who fulfilled the inclusion criteria. Mean age was 55.4 ± 14.5 years old. The patient reported outcome mean results and statistical analysis are shown in Table one below. Mean pre and post-operative foot and ankle VAS pain was 6.73, and 3.13 respectively with a mean difference of 3.6 (p<0.001, 95% CI 2.6, 4.6). Mean pre and post-operative sinus tarsi VAS pain was 6.03 and 3.88, respectively with a mean difference of 2.1 (p<0.001, 95% CI 0.9, 3.4). Mean pre and post-operative EQ-5D Pain scores were 2.19 and 1.83 respectively with a mean difference of 0.4 (p=0.008, 95% CI 0.1, 0.6). Mean follow up time was 18.8 ± 18.4 months.

Peroneus brevis to longus tendon transfer and gastrocnemius recession in the management of symptomatic progressive collapsing foot deformity significantly improved sinus tarsi and overall foot and ankle pain. Most EQ-5D scores improved, but did not reach statistically significant values with the exception of the pain score. This may have been limited by our cohort size. To our knowledge, this is the first report in the literature describing clinical results in the form of patient reported outcomes following treatment with this combination of isolated soft tissue procedures for the treatment of PCFD.

For any figures or tables, please contact the authors directly.

Aims

Metal-on-metal total hip replacements (MoM THRs) are frequently revised. However, there is a paucity of data on clinical outcomes following revision surgery in this cohort. We report on outcomes from the largest consecutive series of revisions from MoM THRs and consider pre-revision factors which were prognostic for functional outcome.

Introduction

The prevalence of adverse reactions to metal debris (ARMD) associated with metal on metal (MoM) hip arthroplasty has been reported to be as high as 69%. Such findings promoted the development of metal-artefact reducing sequence (MARS)-magnetic resonance imaging (MRI) classifications, with the aim of stratifying soft lesions by severity of disease. The Modified Oxford Classification is a straightforward system that has been shown to correlate with disease progression.

Aims

Several national studies have shown that the rates of joint replacement are rising and this increase may be greater than that expected by population ageing. The aim of this study was to assess local rates of joint replacement at a district general hospital (DGH) and to investigate whether there had been a change in pre-operative functional status of patients over the study period to account for any change in rates of arthroplasty.

Introduction

Large head total hip arthroplasty (THA) reduces dislocation rates and provides a theooretically larger range of motion. We hypothesised that this would translate into greater improvement in functional scores when compared to 28mm metal-on-polyethylene THA at 5 years. We believe ours to be the first in vivo comparison study.

It is established good practice that hip and knee replacements should have regular follow-up and for the past seven years at the North Hampshire Hospital a local joint register has been used for this purpose and we compare this with results of the Swedish and UK national and the Trent Regional registries.

Since March 1999, all primary and revision hip and knee arthroplasties performed at North Hampshire Hospital, Basingstoke have been prospectively recorded onto a database set up by one of the senior authors (JMB). Data from patients entered in the first five years of the register were analysed. All patients have at least one year clinical and radiological review then a minimum of yearly postal follow-up. 3266 operations (1524 hips and 1742 knees) were performed under the care of 13 consultants. Osteoarthritis was the most common primary diagnosis in over 75% of hips and knees. Our revision burden was 7.5% (10.2% hips and 3.5% knees). As of 31/12/2006 6.2% of patients had died and 5.5% were lost to follow-up.

Revision rates were 1.5% and 1.4% for primary total hip and knee replacements respectively.

Our data analysis of revisions and patello-femoral replacements has allowed us to change our practice following local audit which is ongoing. Oxford scores at 2 years had improved from a mean of 19 and 21 pre-operatively to 40 and 39 for primary hips and knees respectively. Our costs are estimated at approximately £35 per patient for their lifetime on the register.

Compared to other registries:

Our dataset is more complete and comprehensive

The process of femoral impaction grafting requires vigorous impaction to obtain adequate stability but the force of impaction has not been determined. This process has been reported to result in femoral fractures with rates reaching 16%. The aims of this study were to determine the threshold force required for femoral impaction grafting, to determine the affect cortical thickness, canal diameter and bone mineral density (BMD) have on this threshold force and to measure subsidence of an Exeter prosthesis following impaction at the threshold force.

Adult sow femurs were prepared and placed through a DEXA scanner and the BMD and canal diameter measured. Thirty five femurs were impacted with morsellised bone chips and an increasing force of 0.5kN was applied until the femur fractured. Using callipers the cortical thickness of the bone was measured along the fracture line. Once the threshold force was determined 5 femurs were impacted to this threshold force and an Exeter stem was cemented into the neomedullary canal and a 28mm Exeter head attached. Axial cyclic loading was performed between 440N (swing phase of gait) and 1320N (stance phase of gait) for 150,000 cycles at a frequency of 3Hz. The position sensor of the hydraulic testing machine measured the subsidence.

29 tests were successfully completed. The threshold force was found to be 4kN. There was no significant correlation between the load at fracture and the cortex: canal ratio or the bone mineral density. Following impaction with the maximum force of 4kN the average subsidence for the 5 femurs was 0.276mm (range 0.235 – 0.325mm). In this animal study the threshold force was 4kN. Minimal axial subsidence of the implant occurred when impacting the graft with this threshold force. We therefore achieved a stable construct without fracture which is the ultimate goal for the revision hip surgeon.

The main mode of failure of the acetabular component in total hip arthroplasty is aseptic loosening. Successive generations of cementation techniques have evolved to alleviate this problem.

This paper evaluates one such method, Negative Pressure Intrusion cementation. Two groups of machined bovine cancellous bone samples were created; experimental (n = 26) and control (n = 26). The experimental group was cemented using the negative pressure technique and control group was cemented in the absence of negative pressure. The relative cement intrusion depths were then assessed for each group using MicroCT. These samples were then further machined and tested to failure in torsion to estimate their mechanical properties.

Results show mean cement intrusion depth for the negative pressure group to be 8676μm and 6042 μm for the control group (p = 0.078). Mechanical testing also revealed a greater mean torque in the negative pressure group (1.6223Nm vs 1.2063Nm) (p = 0.095).

This work quantifies the effect of negative intra-osseous pressure on cement intrusion depth in cancellous bone and for the first time relates this to increased mechanical strength.

The cement-in-cement femoral revision is a possible method of reducing complications. During recent research on this revision it was observed that a number of the inner cement contained macropores. It was hypothesized that porosity of the mantle influenced the subsidence and inducible displacement of the revision stems. The aim was to calculate the porosity and assess its relationship to the above factors.

Primary cement mantles were formed by cementing a stem into sections of tubular steel. At this stage, the specimen was chosen to be in a test or a control group. If in the test group, it underwent a fatigue of 1 million cycles. This was carried out in a fatigue machine mounted with a specifically designed rig. If in the control group, no such fatigue was undertaken. Into these fatigued and unfatigued mantles, the cement-in-cement procedure was performed. Both groups underwent a fatigue of again 1 million cycles. Subsidence and inducible displacement was recorded. The composites were then sectioned and photographed. The images underwent image analysis to calculate the porosity.

Multiple regression and a general linear model showed subsidence was inversely correlated to the porosity of the “fresh cement” in Gruen zones 3 and 5 (p = 0.021, R2 = 0.36). This relationship was not expected. The reason could be related to the fact that the migration of the stems in each separate direction was not monitored. Inducible displacement was inversely correlated to porosity of the inner cement, again in Gruen zones 3 and 5 (p = 0.001, R2 = 0.61). A possible explanation is that the stem was able to subside more due to the higher porosity and find a more stable position.

The subsidence and inducible displacement of these stems is influenced by porosity, specifically by the porosity of the distal inner cement.

One method of reducing intra-operative complications in revision hip surgery is the cement-in-cement technique. Some concern exists regarding the retention of the existing fatigued cement mantle. It was hypothesised that leaving the existing fatigued cement mantle does not degrade the mechanical properties of the cement in cement revision construct. The aim of this research was to test this hypothesis using in vitro fatigue testing of analogue cement in cement constructs.

Primary cement mantles were formed by cementing a large polished stem into sections of tubular stainless steel using polymethylmethacrylate with Gentamicin. At this stage, the specimen was chosen to be in the test group or the control group. If in the test group, it underwent a fatigue of 1 million cycles. This was carried out in a specifically designed rig and a fatigue testing machine. Into these fatigued and unfatigued primary mantles, the cement in cement procedure was carried out. Both groups underwent a fatigue of again 1 million cycles. Subsidence of the stems and their inducible displacement was recorded. A power calculation preceded testing.

Completion of a Mann Whitney test on the endpoints of the subsidence curves revealed that there is no statistical difference between the data sets (means 0.51, 0.46, n=10 + 10, p = 0.496). This data was also calculated for the inducible displacement. Again, there was no statistical difference in the separate groups for this parameter (means 0.38, 0.36, p = 0.96). This methodology produces a complex 3 dimensional reconstruction of the cement in cement revision which replicates the in vivo structure. This reconstruction has undergone fatigue testing. Neither of these two aspects has been produced for the study of cement in cement revision before.

A fatigued primary cement mantle does not appear to degrade the mechanical properties of the cement in cement revision construct

Method: This study reports upon 216 patients (97 Minimally invasive and 119 Standard) enrolled into a randomised control trial comparing a standard posterior approach to the hip with a single incision minimally invasive surgery (MIS) posterior approach at 6 weeks and 1 year post-operatively. Primary outcome measures included operative time, blood loss, length of stay and functional hip scores.

Results: The demographics and pre-operative hip scores for both cohorts were statistically similar. Intra-operative blood loss was significantly reduced in the MIS cohort (p=< 0.01). There was no difference in surgical time (p=0.37), time to discharge (p=0.24) or complication rate between the two groups.

Both groups had statistically improved post-operative hip scores, however, at the 1 year follow-up the MIS group were significantly better in terms of WOMAC, Harris Hip, Merle d’Aubigne and SF-12 scores when compared with a standard posterior approach.

Conclusion: This study demonstrates that MIS THA is a safe, reproducible technique in a DGH. We recommend the use of MIS techniques in primary THA and adhere to the principle that an incision need be no longer than necessary to perform the procedure safely.