Aim

To assess the survivorship of unicompartmental replacements (UKR) revised to UKR. Background: Partial revision of UKR, or revision to a further UKR is a rarely performed procedure with some data from the Australian registry suggesting that results are not good, with early revision being required.

The gold standard for measuring knee alignment is the lower limb mechanical axis. This is traditionally assessed by weight-bearing full length lower limb X-rays (LLX). CT scanograms (CTS) are however, becoming increasingly popular in view of lower radiation exposure, speed and supine positioning. We assessed the correlation and reproducibility of knee joint coronal alignment using these two imaging modalities.

LLX and CTS images were obtained in 24 knees with degenerate joint disease or failed TKR. Hip to ankle mechanical alignment were measured using the PACS software. Coronal knee alignment was assessed from the centre of the knee, measuring the valgus/varus angle relative to the mechanical axis. Measurements were made by two orthopaedic surgeons (Research Fellow and Consultant) on two separate occasions.

The mean alignment angles measured by observers 1 and 2 on CTS were 180.29° (SD 6.04) and 180.71° (SD 6.13) respectively, while on LLX were 181.04° (SD7.58) and 181.04° (SD 7.72). The measurements between the two observers were highly correlated for both the CTS (r = 0.97, p < 0.001) and the LLX (r = 0.99, p < 0.001). The angles measured on CTS and LLX were highly correlated (r = 0.826, p < 0.001) with high degree of internal consistency (ICC = 0.804). Malalignment of greater than 5° was seen in 19% of the CTS and 35% of the LLX.

There was good correlation between CT scanogram and weight-bearing X-ray measurements in normally-aligned knees. However, as expected, in the malaligned lower limb, the influence of weight-bearing is critical which demonstrates the significance of weight-bearing X-rays.

Patello-femoral arthritis can result in a considerable thinning of the patella. The restoration of an adequate patella thickness is key to the successful outcome of knee arthroplasty.

The objectives were (1) to establish a reproducible patella width:thickness index including chondral surface and (2) to investigate whether there is a difference between bone alone and bone/chondral construct thickness as shown by MRI.

Forty three MRI scans of young adults, mean age 27 (range 17–38), 34 male and 9 female, were studied. Exclusion criteria included degenerative joint disease, patello-femoral pathology or age under 16/over 40 (102 patients). The bony and chondral thickness of the patella and its width were measured. Inter/intra observer variability was calculated and correlation analysis performed.

We found a strong correlation between patella plus cartilage thickness and width (Pearson 0.75, P < 0.001). The mean width:thickness ratio was 1.8 (SD 0.10, 95% CI 1.77–1.83). Without cartilage the ratio was 2.16 (SD 0.15, 95% CI 2.11–2.21), correlation was moderate (Pearson 0.68, P < 0.001). The average patella cartilage thickness was 4.1mm (SD 1.1, 95% CI 3.8–4.5).

The narrow confidence intervals for the ratio of patella width:thickness suggest that patella width can be used as a guide to accurate restoration of patella thickness during total knee or patella-femoral replacement. We would recommend a ratio of 1.8:1.

Patients with severe knee instability remain a surgical challenge. Furthermore, in the presence of extensive bone loss, constrained condylar implants may be unsuitable.

Hinged knee replacements have served an important role in the management of such complex knee pathologies.

A combined prospective and retrospective study of 138 consecutive hinge knee arthroplasties (42 primary and 96 revisions) of 8 different models performed in our institution between 2004 and 2010 at a mean follow up of 4.2years.

Outcomes were reviewed and knee scores preoperatively and postoperatively at 1, 2 and 5 years using the American knee scoring system.

The mean preoperative American knee score of 31 improved to 87 postoperatively.

Complication rate was 19%, 15% of which required re-revisions for: loosening (4%), Infection (4%), periprosthetic fracture (3%), Implant fracture (2%), Component disassembly (1%) and dislocation (1%). Overall implant failure rate was 9% and implant survivorship was greater than 80% at 4 years.

In our study, hinge prostheses provided good stability and symptom relief with a lower complication rate compared to some previous studies.

In addition, we believe hinge prostheses can also serve as reasonable alternatives to amputation and arthrodesis in many complex knees cases.

Introduction

Patients with severe knee instability and extensive bone loss remain a surgical challenge. In such cases, regular knee implants and constrained condylar implants may not be suitable or have been attempted and failed.

Hinged knee replacements have developed an important role in the management of such complex knee cases. They also have an increasingly important role in cases such as rheumatoid arthritis and other cases of severe joint destruction.

We present a review of 138 consecutive hinge knee arthroplasties of 8 different Hinge models performed in our unit between 2004 and 2010.

Separation of the ACL into anteromedial (AM) and posterolateral (PL) fibre bundles has been widely accepted. The bundles act synergistically to restrain anterior laxity throughout knee flexion, with the PL bundle providing the more important restraint near extension and its obliquity better restraining tibial rotational laxity.

10% of ACL injuries involve isolated rupture to one of these bundles causing patients to present with instability symptoms or pain. As knowledge about the influence of the ACL bundles on knee kinematics has increased, isolated reconstruction of either PL or AM bundle has been advocated. However only one cohort study of 17 patients has been presented in the clinical literature.

KOOS (Knee Injury and Osteoarthritis Outcome Score) and IKDC (International Knee Documentation Committee Form) scores at 1yr post op were obtained for 12 patients who had undergone isolated ACL augmentation between 2007 and 2009. These were compared with previously published outcome scores for standard ACL reconstruction procedures. In addition examination under anaesthesia (EUA) assessments were analysed to see if a pattern of laxity for isolated AM and PL rupture could be determined.

There were 5 patients with isolated AM bundle rupture and 7 with isolated PL bundle rupture. EUA analysis demonstrated that patients with isolated PL bundle rupture had increased pivot shift and Lachman test laxity, whereas the AM bundle rupture group had increased laxity with the anterior drawer test. Compared to previously published IKDC scores, there were no difference between isolated bundle augmentation and standard ACL reconstruction. However the KOOS scores showed significantly increased Sports function scores which was significantly better in the isolated bundle augmentations (93/100 v's 74/100). Differences between isolated AM and PL bundle reconstructions were not distinguishable.

Isolated ACL bundle tears make up a significant proportion ACL injuries. Although technically more difficult than standard ACL reconstruction, isolated bundle augmentation appears to result in improved sports function when compared to standard ACL reconstruction.

Introduction

The legion knee revision system was designed as a follow and improvement to the Genesis II knee system- allowing for a surgeon directed femoral rotation as opposed to the in-built femoral rotation in the previous system.

This is a prospective review of consecutive patients who underwent knee revision surgery using the legion knee system.

Purpose

The aim of this study was to compare the short-term and mid-term outcome of lateral UKRs using a single prosthesis, the AMC Uniglide knee implant.

Introduction

Kneeling ability is better in unicompartmental than total knee arthroplasty. There is also an impression that mobile bearing knees achieve better functional outcome than their fixed bearing cousins in unicompartmental and to a lesser extent total joint arthroplasty. In the UK, the market leading unicompartmental replacement is mobile bearing.

PURPOSE

The aim of this study was to study the short-term outcome of a contemporary modular revision knee system used in our centre for managing Knee revision arthroplasty

Background

Body Mass Index (BMI) is used to quantify generalised obesity, but does not account for variations in soft tissue distribution.

Purpose of the study

Assessing medium term outcome of medial Uni compartmental replacement and whether there is a difference in outcome between mobile and fixed bearing variants of the same prosthesis.

There are a few papers in the literature to indicate the likely functional outcome of conservatively managed sportsmen in whom primary outcome cruciate ligament [ACL] healing occurs.

We reviewed 298 sportsmen presenting with isolated ACL rupture that were conservatively managed with a rehabilitation programme, based on regaining proprioceptive and hamstring control, and aimed at achieving primary ACL healing. All were protected in a hinged brace. In 50 patients, the ACL was determined as having healed clinically; these patients underwent instrumented laximetry testing with KT 1000 arthrometry and were determined: IKDC A [Normal] or IKDC B [nearly normal]. An MRI was also performed which confirmed healing in 39 patients with ACL fibres parallel to Blumenstat's line. In 11 patients the ACL stump had healed to the PCL. The 50 patients were followed up for an average 16 months [range, 14 to 17 months].

56% of patients suffered recurrent instability when they returned to their preinjury level of contact or pivoting sport. For competitive athletes, 76.5% suffered further instability on return to sport despite the four-month rehabilitation and independent arthrometry score or MRI findings. However, for occasional, recreational athletes only 7% suffered recurrent instability.

This study suggests that a rehabilitation programme aimed at primary ACL healing affords satisfactory results for the occasional, recreational athlete but does not achieve the quality of restraint sufficient for contact or pivoting sports in competitive athletes. These patients suffer high levels of recurrent instability and are exposed to the risk of secondary chondral and meniscal injury.

Introduction: Distal third fractures of the clavicle account for approximately 10–15% of clavicle fractures. Non union rates following conservative management can be as high as 30%. Many techniques have been described, including external fixation, k-wire fixation, and most recently, hook plate fixation. Non-absorbable sutures, and slings have also been utilised. All of these techniques are associated with complications. In addition, Hook plates require a second operation to remove the plate. This study reports the results of a simple technique using a PDS loop in the fixation of Neer type 2 fractures of the clavicle, performed in our institution.

Methods: Twelve patients with Neer type 2 fractures operated by a single surgeon over three years were included in the study. The mean age was 45 (14 to 63). There were 7 male and 5 female patients. Standard postoperative protocols were followed in all patients. A 1.5 PDS cord looped around the coracoid was used to hold the reduced medial clavicular shaft fragment. Patients were followed up postoperatively at two, six and twelve weeks. Final outcomes were assessed using radiographs and the Oxford and DASH scoring systems at twelve months.

Results: Ten fractures united within twelve weeks. All of these patients returned to their pre-injury activity level. There were two non unions, both in non compliant patients. One of these non unions remained asymptomatic and one patient was lost to follow up. The mean Oxford score at 12 months was 14.25 (range 12 to 16) and the mean DASH score was 5 (4–7).

Conclusion: We conclude that this technique is safe, simple and cost effective. It achieves high rates of union without the need for implant removal. As with other techniques, proper patient selection is essential. We recommend this technique as an excellent treatment option when dealing with these notoriously difficult fractures.

Background: Although many knee surgeons routinely perform unicompartmental replacement (UKR) for medial compartment arthrosis there is still reluctance to perform lateral UKR’s as they are generally thought to be less satisfactory. The purpose of the present study was to prospectively compare the outcome of lateral UKR’s with medial UKR’s using the AMC Uniglide knee implant.

Methods: Between 2002 and 2005, 29 lateral fixed bearing AMC Uniglide UKR’s were performed at our unit. American Knee Society (AKS), Oxford and WOMAC scores were recorded pre-operatively and at two years post-op and compared with the results of 50 medial mobile bearing and 50 medial fixed bearing AMC Uni-glide UKR’s performed during the same time period. Data was acquired by a research nurse and recorded prospectively on the Bristol Knee Database. The mean ages of the patients were: 63 years in the lateral UKR group was, 62 years in the medial mobile bearing group and 69 in the medial fixed bearing group. The groups were equally sex matched with a predominate number of females in each group. There was no difference between the pre-operative scores for the 3 groups.

Results: At one-year review, the 3 groups had similar mean scores: (table removed)

Conclusions: This study suggests that at two years the quality of outcome of Lateral UKR’s is at least equivalent to both fixed and mobile bearing medial compartment UKR’s. However, continued long-term survivorship studies are needed to assess failure rates of Lateral fixed bearing UKR’s and particularly to evaluate progression of arthritis in the medial compartment. The procedure should form part of the knee surgeons’ armamentarium, but the differences in the operative techniques for lateral and medial UKR must be appreciated.

Although good long term results for fixed bearing uni-compartmental knee replacements (UKRs) have been reported mobile bearings predominate in some parts of the world. Three prospective studies have been undertaken comparing the short and medium term outcomes of fixed and mobile UKRs.

A 5 year comparative cohort study of 47 Oxford mobile bearing and 57 St Georg Sled fixed bearing UKRs.

In all groups the preoperative sex mix, average age and knee scores were extremely similar.

All patients were assessed both pre and postoperatively by a research nurse and radiographs were taken; the results were entered on the Bristol Knee database.

Results:

Multiple problems were encountered, perhaps because of the introduction of MIS, but at 5 years 11 Oxford and 4 Sleds had failed. The major problem with the mobile bearing implant was instability though tibial fractures were also seen. Both groups had three cases of arthritic progression and loose cement was seen twice in the fixed bearing group.

– Amongst the remaining patients the median scores for the Sled were better. Bristol Knee Score (Max 100) 95:90; Oxford (Max 48) 39:37; and reduced WOMAC (Best score 12) 18:24.

Conclusion. Although theoretically mobile bearings will give greater longevity there is frequently a short term price to pay particularly when the procedures are performed by inexperienced surgeons and trainees. Since the wear properties of polyethylene have improved in recent years these studies suggest that a fixed bearing option can be used more safely in many patients.

Purpose: To define the positions of the attachments of the anteromedial (AM) and posterolateral (PL) bundles of the ACL facilitating accurate tunnel placement during two-bundle reconstruction.

Methods: The positions of the femoral and tibial attachments of the AM and PL bundles was determined in 7 fresh-frozen, unpaired, cadaveric knees by 6 independent observers, using landmarks visible at arthroscopy. This included, on the tibia, the retro-eminence ridge (lying just anterior to the PCL), a bony landmark that could be reliably identified arthroscopically. Tantallum beads were then inserted so that the bundle attachments could be clearly identified on a plain lateral radiograph of the knee. The position of the centres of the AM and PL attachments were described relative to Amis and Jakob’s line on the tibia and Bernard’s grid on the femur.

Results: The AM femoral attachment lay high and deep in the notch with the most posterior fibres 1.8 mm anterior to the “over–the-top” position. The PL femoral attachment was low and shallow in the notch with the most anterior fibres 2.8 mm from the border of the articular cartilage. The centres of the bundles were 8.2 mm apart. The position of the bundles relative to Bernhard’s grid is shown in figure 1.

On the tibia, the centre of the AM attachment was located 18 mm anterior to the Retro-eminence ridge (RER). The centre of the PL bundle lay 8.4 mm posterior to the centre of the AM bundle. These positions were at 35% and 52% along Amis and Jacob’s line

Conclusions: This study details the morphology of the AM and PL bundle attachments and demonstrates reliable arthroscopic techniques to assist with accurate tunnel placement in reconstruction surgery. In addition, it provides reference data for radiographic evaluation of tunnel placement.

Background: Computer Assisted Orthopaedic Surgery continues to evolve. Electromagnetic Computer Navigation has recently emerged as a new modality of CAOS that promises increased accuracy, as well as increased portability and practicality. However, there are very few studies examining this new technique and comparing it to conventional TKJR.

Methods: We carried out a prospective randomised study comparing the conventional jig-based technique of TKJR versus EM navigation (Medtronic). We examined parameters such as surgical time, blood loss, days in hospital post operatively, and complication rate. Further, we assessed the accuracy of the two techniques with the CT Scan “Perth Protocol”. Parameters measured included femoral component flexion, extension, alignment and rotation, tibial alignment, posterior slope and femorotibial mismatch.

Results: Mean Oxford Knee Score was 47.5; the mean age was 70 (67–74). 43% were female and 57% male. Half were navigated and half conventional. The mean Hb change in 48 hours, as a reflection of blood loss was 14.5% for the conventional group and 14.25% for the navigated group. Mean Surgical Time for the conventional group was 90 minutes and the navigated was 120 minutes. The average stay in hospital for both groups was 5 days after the operation. The measurements according to the Perth Protocol suggested increased accuracy in femoral alignment, posterior slope, and reduced femorotibial mismatch. Femoral rotation was not significantly different and femoral flexion extension was not significantly different. The only major complication occurred in the navigated group with a dislocated knee in a patient afflicted with multiple sclerosis.

Summary: These preliminary results suggest that EM navigation is a safe and accurate technique. It has the additional advantage of portability and increased user friendliness compared to other navigation methods. When compared to conventional jig-based techniques, it is more accurate, increases surgical time by an average 30 minutes, there is no significant difference in blood loss at 48 hours, patient’s stay in hospital is not prolonged and the rate of complications does not exceed that of conventional surgery.

Electromagnetic Navigation is in its infancy, and the authors feel that surgical time and accuracy will improve with more frequent use and the development of increasingly more sophisticated software packages. Our study continues.

Background: We have noted a concerning number of early failures (as defined by revision) for Preservation medial mobile-bearing uni-compartmental knee replacements (UKR’s) implanted in our hospital. This study retrospectively reviewed the postoperative radiographs to see if these were as a result of surgical technical failure.

Methods: Between 2003 and 2004, 43 medial mobile-bearing Preservation UKR’s were implanted into 39 patients. The average age of the patients at the time of the index procedure was 61.4 years (range, 46–85), (20 males). The immediate post-operative radiographs were reviewed by 2 independent orthopaedic consultants and a registrar, who were blinded to the patient outcomes, using the radiographic criteria used for the Oxford UKR. We however, particularly tried to identify any medio-lateral offset between femoral and tibial components due to the constrained nature of the prosthesis. A compound error score for all other technical errors was also calculated for each patient.

Results: Six (13.9%) of 43 knees were revised (5 for persistent pain, 1 for tibial component subsidence). Technical errors were few and no correlation was found between post-operative radiographic appearances and the subsequent need for revision. The mean compound error score (maximum value 18) was 4.5 (range, 2–9) in the revision cases and in the non revised cases 3.2 (range, 0–8).

Conclusions: We believe this study gives credence to the opinion that the DePuy Preservation mobile-bearing implant has design faults and is over-constrained leading to early failures in some cases.

Introduction: Objective of study is to provide a quantitative description of the amount of RLN irritation during ACDF and to correlate the amount of irritation with operative parameters.

Methods: In a series of 98 patients undergoing ACDF continuous IEMG monitoring of the vocal cords was performed with a specially designed, commercially available Endotracheal Tube. The amount of irritation was described as irritation score (IS) by use of our proposed formula IS=log( ∑ (AxD)/B ), where A is the amplitude of irritation, D the duration of irritation and B the baseline irritation

Results: The amount of RLN irritation as described by our formula was statistically higher in patients that had undergone previous surgery compared to de novo cases (p= 0.024), and in cases where self retained retractors were used compared to handheld retractors (p= 0.020). Although results were not statistically significant, the irritation score was higher in patients presented with postoperative hoarseness.

Conclusions: The use of our proposed scale may be a useful adjunct in the prevention of RLN injury in patients undergoing ACD with or without fusion.