Introduction

To determine if elite athletes can return to professional sport after MCL or posterolateral (PLC) reconstruction using LARS ligaments. The secondary aims are to demonstrate the safety and efficacy of LARS by reporting sport longevity, subsequent surgeries, and complications.

Abstract

Abstract

Abstract

Abstract

Introduction:

To date, there have been few reports of the results of revisions for failed metal-on-metal hip arthroplasties (MoM HA's). These series have included relatively modest numbers, and classification of the severity of adverse local tissue reaction (ALTR) has been under-reported. In this study, early outcomes and complications are analyzed as a function of pre-operative MRI grade and intra-operative ALTR severity to determine their prognostic value.

Computer navigation has the potential to revolutionise orthopaedic surgery, although according to the latest 7^th Annual NJR Report, only 2% of the 5 800 unicompartmental knee replacements (UKRs) performed in 2009 were carried out using ‘image guidance.’ The report also states an average 3-year revision rate for UKRs of 6.5%. Previous NJR data has shown that this figure rises up to 12% for certain types of prosthesis. We suspect that a significant proportion of these revisions are due to failure secondary to component malpositioning. We therefore propose that the use of computer navigation enables a more accurate prosthesis placement, leading to a reduction in the revision rate for early failure secondary to component malpositioning. Our early results of one hundred consecutive computer navigated UKRs are presented and discussed.

Ninety-two patients having had one hundred consecutive computer navigated UKRs were reviewed both clinically and radiographically. The Smith & Nephew Accuris fixed-bearing modular prosthesis was used in all cases, with the ‘Brainlab’ navigation system. Pre-operative aim was neutral tibial cut with three degrees posterior slope. Post-operative component alignment was measured with PACs web measuring tools. Patients were scored clinically using the Oxford Knee Score.

Our patient cohort includes 54 male knees and 46 female knees. Average age is 66.6yrs. Average length of stay was 3.7 days, (range 2–7.) With respect to the tibial component, average alignment was 0.7° varus, and 2.32° posterior slope. All components were within the acceptable 3 degrees deviation. Functional scores are very satisfactory, with an overall patient satisfaction rate of 97%.

To date, only one UKR has required revision. This was due to ongoing medial pain due to medial overhang, not related to computer navigation. There was one superficial infection, with full resolution following a superficial surgical washout, debridement and antibiotics. Unlike complications reported in the NJR, we report no peri-prosthetic fractures or patella tendon injuries.

Our results demonstrate accurate prosthesis placement with the use of computer navigation. Furthermore, clinical scores are highly satisfactory. Our current revision rate is 1% at a mean of 27 months post-op. Although longer-term follow-up of our group is required, our results compare very favourably to statistics published in the NJR, (average 3-year revision rate 6.5%.) The only major differences appear to be the type of prosthesis used and the use of computer navigation. It is our proposal that computer navigation reduces the number of revisions required due to component malpositioning and subsequent failure. Furthermore, we believe that this challenging surgery is made easier with the use of computer navigation. We expect our longer-term results to show significant benefits of computer navigation over conventional techniques.

Cervical spine collars are applied in trauma situations to immobilise patients' cervical spines. Whilst movement of the cervical spine following the application of a collar has been well documented, the movement in the cervical spine during the application of a collar has not been. There is universal agreement that C-spine collars should be applied to patients involved in high speed trauma, but there is no consensus as to the best method of application.

The clinical authors have been shown two different techniques on how to apply the C-spine collars in their Advanced Life Support Training (ATLS). One technique is the same as that recommended by the Laerdal Company (Laerdal Medical Ltd, Kent) that manufactures the cervical spine collar that we looked at. The other technique was refined by a Neurosurgeon with an interest in pre-hospital care. In both techniques the subjects' head is immobilised by an assistant whilst the collar is applied.

We aimed to quantify which of these techniques caused the least movement to the cervical spine. There is no evidence in the literature quantifying how much movement in any plane in the unstable cervical spine is safe. Therefore, we worked on the principle: the less movement the better.

The Qualisys Motion Capture System (Qualisys AB, Gothenburg, Sweden) was used to create an environment that would measure movement on the neck during collar application. This system consisted of cameras that were pre-positioned in a set order determined by trial and error initially. These cameras captured reflected infra-red light from markers placed on anatomically defined points on the subject's body. As the position of the cameras was fixed then as the patients moved the markers through space, a software package could deduce the relative movement of the markers to each camera with 6 degrees of freedom (6DOF).

Six healthy volunteers (3 M, 3 F; age 21-29) with no prior neck injuries acted as subjects. The collar was always applied by the same person. Each technique was used 3 times on each subject. To replicate the clinical situation another volunteer would hold the head for each test.

The movements we measured were along the x, y, and z axes, thus acting as an approximation to flexion, extension and rotation occurring at the C-spine during collar application. The average movement in each axis (x, y and z) was 8 degrees, 8 degrees and 5 degrees respectively for both techniques. No further data analysis was attempted on this small data set.

However this pilot study shows that our method enables researchers to reproducibly collect data about cervical spine movement whilst applying a cervical collar.

Recently, monoblock cups have increased in popularity for hip resurfacing and large femoral head total hips. However, there have been no studies specifically evaluating the durability of this type of cup. The purpose of this study was to define the mid-term survivorship of cobalt-chrome alloy, monoblock acetabular components.

A retrospective radiographic review of 426 consecutive hip resurfacings using the ConserveÒPlus prosthesis was performed with specific attention to the acetabular component.

Radiographs were analyzed for cup position, the presence of radiolucencies, cup migration, bead shedding, osteolysis and stress remodeling of the pelvic bone. Kaplan-Meier (KM) survival estimates were calculated using revision for aseptic loosening of the acetabular component as the end point.

Average follow-up was 8.6 years (range 5.4 to 12.3). Mean abduction angle and anteversion angle were 46.6° (± 6.8°), and 21.6° (± 8.6°), respectively. Radiolucent gaps behind the cup from incomplete seating were visible in zone 2 in 16% of cases. These were typically 1 to 2 mm in size and radiographically filled in all but 2 cases. No cups with early lucencies went on to fail. Late radiolucencies developed in zone 1 in 8 cups (1.9%), in zone 2 in 8 cups (1.9%), and in zone 3 in 19 cups (4.5%). Radiolucencies in multiple zones were seen in 6 cups (1.4%).

Small amounts of socket migration (2mm or less) were suspected in 3 cups (0.7%) but each of these has remained stable. There were no cases of bead shedding. Small osteolytic lesions were suspected in 12 hips (2.8%). There were 2 revisions for aseptic loosening of the cup at 5 and 8 years, and one revision for protrusion of the cup through the medial wall 4 days after surgery.

Additionally, one cup at 9 years follow-up is believed to be loose but has yet to be revised. The KM survival estimate was 99.6% at 5 years (95% C.I. 98.4% to 99.9%) and 98.7% at 10 years (95% C.I. 94.5% to 99.7%).

In conclusion, this study demonstrates excellent mid-term survivorship of a cobaltchrome alloy monoblock acetabular component, which matches that of conventional titanium implants. Small early gaps seen behind the cup from incomplete seating do not appear to effect cup survivorship as long as a good peripheral press-fit is obtained. Osteolysis with this prosthesis is rare but does occur.

Computer navigation has the potential to revolutionise orthopaedic surgery. It is widely accepted that component malalignment and malrotation leads to early failure in knee arthroplasty. We aimed to assess the use and reliability of computer navigation in both total (TKR) and unicompartmental (UKR) knee replacement surgery.

We analysed 40 consecutive UKRs and 40 consecutive TKRs. All procedures were carried out with the Brain-LAB navigation system and all were carried out by one consultant orthopaedic surgeon. Preoperative aim was neutral tibial cuts with 3 degrees posterior slope. Coronal and sagittal alignment of tibial components were measured on postoperative radiographs. Patients were also scored clinically with regards to function and pain.

In the TKR group, mean tibial coronal alignment was 0° (range 1 to −2.) Mean sagittal alignment was 2° posterior slope (range 0 to 4.) In the UKR group, mean tibial coronal alignment was 0.55° (range 0 to −3.) Mean sagittal alignment was 2.1° posterior slope (range 0 to 4°.) Clinical outcome scores were very satisfactory for the majority of patients, with far superior functional scores in the UKR group.

Our results demonstrate very accurate placement of the prosthesis in both the TKR and UKR group with computer navigation. There is a very narrow range with no outliers, (all within +/−3 degrees of desired alignment.) Functional outcome scores are good. We advocate the use of computer navigation in unicompartmental as well as total knee replacment surgery, in order to minimise early failures.

Reconstructive knee arthroplasty in patients with limb deformity can be a daunting and complex task. These patients are often younger and so post traumatic osteoarthritis poses a real challenge. In view of their relative youth, bone preservation would be favourable; however accurate implantation of components is essential. Formulation of a well calculated plan and accurate execution is essential for successful surgery.

We report on a novel method which combines 3D CT joint analysis and computer navigation to define the deformity present pre-operatively and determine whether the proposed reconstruction is feasible. If the reconstructive surgery is feasible, an accurate calculation the correction required is performed. The planned surgery is executed using computer aided navigation surgery.

Eight patients have benefited from the technique. Four patients presented with isolated medial compartment osteoarthritis and intact anterior cruciate ligament. These patients underwent 3D CT joint analysis and computer assisted navigation surgery to accurately implant unicondylar knee replacements.

Four Patients presented with two or three compartment disease. These patients underwent similar 3D CT analysis and navigated Total Knee Replacement.

The series demonstrates the merits of 3D CT joint analysis to accurately define deformity and therefore determine pre-operatively feasibility of corrective surgery proposed. The technique is then complimented by computer assisted navigation surgery to ensure the proposed surgical plan is accurately executed.

Over 80% of patients are satisfied following total knee arthroplasty (TKA). Female gender was one of the factors found to be a predictor of poorer satisfaction. The landmarks commonly used to achieve correct rotation of the femoral component are the posterior condylar axis, the transepicondylar axes (TEA) & the anteroposterior axis (Whiteside’s line) of the distal femur. The design features of most conventional jig based TKA instrumentation assumes a constant relationship of 3 degrees external rotation between the posterior condylar axis & the epicondylar axis. However during TKA using computer assisted navigation, we observe that these rotational landmarks do not have a constant relationship & there is wide variation among the arthritic population & between the male & female rotational profile. We hypothesise no consistent relationship between the posterior condylar axis, the TEA & the anteroposterior axis of the distal femur.

125 Computerised Tomography (CT) scans of the knee were performed using a 3D helical CT scanner in subjects who did not have any pre-existing clinical & radiological evidence of knee arthritis. CT slices 3 mm in thickness were obtained over the distal femur from the level of the proximal pole of the patella. Standard protocols were established for identifying the bony landmarks & taking measurements. The posterior condylar axis, the TEA & the anteroposterior axis were constructed. The condylar twist angle (CTA), the posterior condy-lar angle (PCA) & the angles made by the TEA & the line perpendicular to the anteroposterior axis were then measured using the PACSWEB digital measurement tools. The data was analysed to determine the consistency of the angular relationship between the reference axes using the STATA data analysis & statistical software. Linear regression was used to investigate any differences in the angle measurements between genders.

125 CT scans of the knee were performed in 111 patients (60 males [65 knees] & 51 females [60 knees]). The mean age was 45 years (SD, 15 years). The results showed no significant difference between the rotational axes of the distal femur between men & women (CTA male(SD): female(SD): 5.9(1.6): 6.3(2.0) [p=0.317], PCA male(SD): female(SD): 2.3(1.5): 2.5(1.9) [p=0.648]). The results also showed it would be inappropriate to assume a constant relationship of 3 degress external rotation between the posterior condylar axis & the epicondylar axes (PCA mean (SD) 2.39(1.70) [p< 0.001], CTA mean (SD) 6.11(1.81) [p< 0.001]).

Our study suggests no significant difference between the rotational reference axes of the distal femur between men & women. Furthermore, most jig-based systems result in 3 degress external rotation of the femoral component. Our results show this is not consistent & may be responsible for the pain in 20% of patients post TKA because of abnormal patellar tracking.

Introduction: ‘Revisability’ has been touted as one of the major advantages of resurfacing arthroplasty of the hip. However, this theoretical advantage has never been clearly demonstrated. The objective of the present study was to test the hypothesis that a failed, modern generation metal-on-metal resurfacing arthroplasty (MMRA) can be converted to a total hip (THA) as easily and with comparable results as a primary (THA).

Methods: Twenty-two failed MMRA’s in 21 patients with an average age of 49.5 years (23 – 72 years) were converted to a THA. In 18 hips, the acetabular component was retained, and in 4 hips both components were revised. The control group of primary THA’s, implanted during the same time period by the same surgeon, consisted of 64 patients with an average age of 50.8 years (27 – 64 years).

Results: There was no significant difference in operative time, blood loss and complication rates between the conversions and the controls. The average follow-up was 47 months (12 – 113 months) for the conversions and 57 months (24 – 105 months) for the controls. Clinical outcomes measures were comparable with average Harris Hip Scores of 92.7 and 90.3 for the MMRA conversions and primary THA’s, respectively. The UCLA activity scores were 6.6 and 6.4 in the conversion group and THA group, respectively. There have been no cases of aseptic loosening of the femoral or acetabular components in either group, and there have been no dislocations after MMRA conversion.

Conclusion: Conversion of failed MMRA to a THA appears to be as safe and effective as a primary THA.