Abstract

Knee ligament injury is one of the most frequent sport injuries and ligament reconstruction has been used to restore the structural stability of the joint. Cycling exercises have been shown to be safe for anterior cruciate ligament (ACL) reconstruction and are thus often prescribed in the rehabilitation of patients after ligament reconstruction. However, whether it is safe for posterior cruciate ligament (PCL) reconstruction remains unclear. Considering the structural roles of the PCL, backward cycling may be more suitable for rehabilitation in PCL reconstruction. However, no study has documented the differences in the effects on the knee kinematics between forward and backward pedaling. Therefore, the current study aimed to measure and compare the arthrokinematics of the tibiofemoral joint between forward and backward pedaling using a biplane fluoroscope-to- computed tomography (CT) registration method.

Eight healthy young adults participated in the current study with informed written consent. Each subject performed forward and backward pedaling with an average resistance of 20 Nm, while the motion of the left knee was monitored simultaneously by a biplane fluoroscope (ALLURA XPER FD, Philips) at 30 fps and a 14-camera stereophotogrammetry system (Vicon, OMG, UK) at 120 Hz. Before the motion experiment, the knee was CT and magnetic resonance scanned, which enabled the reconstruction of the bones and articular cartilage. The bone models were registered to the fluoroscopic images using a volumetric model-based fluoroscopy-to-CT registration method, giving the 3-D poses of the bones. The bone poses were then used to calculate the rigid-body kinematics of the joint and the arthrokinematics of the articular cartilage. In this study, the top dead center of the crank was defined as 0° so forward pedaling sequence would begin from 0° to 360°.

Compared with forward pedaling, for crank angles from 0° to 180°, backward pedaling showed significantly more tibial external rotation. Moreover, both the joint center and contact positions in the lateral compartment were more anterior while the contact positions in the medial compartment was more posterior, during backward pedaling. For crank angles from 180° to 360°, the above-observed phenomena were generally reversed, except for the anterior-posterior component of the contact positions in the medial compartment.

Forward and backward pedaling displayed significant differences in the internal/external rotations while the rotations in the sagittal and frontal planes were similar. Compared with forward cycling, the greater tibial external rotation for crank angles from 0° to 180° during backward pedaling appeared to be the main reason for the more anterior contact positions in the lateral compartment and more posterior contact positions in the medial compartment.

Even though knee angular motions during forward and backward pedaling were largely similar in the sagittal and frontal planes, significant differences existed in the other components with different contact patterns. The current results suggest that different pedaling direction may be used in rehabilitation programs for better treatment outcome in future clinical applications.

Aims

Compartment syndrome (CS) is a well-recognised, serious complication of long bone fractures. The association between CS and tibial shaft fractures is well documented in adult patients and in children with open or high velocity trauma. There is, however, little literature on the risk of developing CS in children with closed tibial fractures. In a number of units these children are routinely admitted for elevation and monitoring for CS.

We audited our experience of managing paediatric tibial fractures to ascertain whether it may be safe to discharge a sub-group of these children.

To evaluate the efficacy of Vacuum Assisted Closure (VAC) in the management of post surgical spinal sepsis.

A retrospective analysis was performed of patients with severe post operative spinal wound infections treated using a combination surgical debridement, antibiotics and VAC therapy.

Full records were available for a total of twenty adult all of whom had had prior thoracic or lumbar instrumentation. Comorbidities included disseminated carcinomatosis (25 % of patients), Ankylosing spondylitis (5 %), rheumatoid arthritis (5%) and Polio (5%). In one patient there had been a prior history of irradiation of the surgical field. Most infections treated by this regime were identified within two weeks following surgery. At surgery infection deep to the dorso-lumbar fascia was found in 87 % of cases. It was possible to retain instrumentation in 60 % of cases. An average of three trips to theatre were required prior to wound closure, which was possible in 95 % of cases. The VAC device was left in situ for an average of 11 days. Complications included recurrence of infection necessitating further treatment in 20 % of cases, wound dehiscence necessitating healing by secondary intention in 5%, the need for free flap wound cover in 5 % and death from unrelated causes in 5%.

VAC therapy may facilitate the management of wound sepsis following spinal surgery in susceptible patients allowing the maintenance of instrumentation and surgical correction.

Aim of Study: To assess the efficacy of Computerised Strain Gauge Plethysmography (CSGP) to screen for proximal Deep Venous Thrombosis (DVT) following Total Knee Replacement (TKR).

Introduction: CSGP is a non invasive, bedside screening tool, used to detect the presence of proximal lower limb DVT. CSGP uses a low pressure thigh cuff to first occlude venous outflow. When the cuff is released the device is used to measure changes in calf dimensions (by means of strain gauges tied around a standardised point of the calf of the patient’s operated limb) thereby giving a measure of venous outflow. Obstruction to outflow (producing a positive result with the device) is seen with occlusion of proximal veins.

Patients & Methods: A retrospective analysis of 184 consecutive patients who had undergone primary TKR was performed. Foot pumps were used for thrombophylaxis during the erioperative period. On the fifth post operative day all patients were screened for proximal DVT using CSGP. Those with a negative result who were ambulating safely were discharged. Those with a positive test had further imaging to confirm or refute the diagnosis of proximal DVT in the operated limb. The patients’ medical notes were scrutinised for evidence of re attendances and evidence of whether proximal DVT was diagnosed following discharge from the ward.

Results: The negative predictive value of CSGP was found to be 99%. The sensitivity of CSGP for detecting proximal DVT was 83 %. The specificity was found to be 69%. The false positive rate was 92%.

Conclusion: CSGP allows the safe and prompt discharge of TKR patients who testnegative with CSGP with some degree of confidence. Patients who test positive with CSGP however require further imaging to select out those individuals who have clinically significant proximal DVT meriting full anticoagulation post operatively.

We report our experience of revision shoulder arthroplasty at Wrightington Hospital. Thirty-Nine patients had undergone revision surgery and followed up for a minimum of two years. Patients were scored using the Constant score and the ASES score pre-operatively and post operatively. All patients had X-ray evaluation for loosening and migration. Of the thirty-nine patients, 16 were failed humeral head replacement (HHR) and 16 were failed total shoulder replacement (TSR). All but two of the HHR were revised for glenoid erosion to a TSR, there was an equal proportion of patients with rheumatoid arthritis and osteoarthritis. Of the 16 patients undergoing revision surgery for failed TSR 6 were rheumatoid, 4 had osteoarthritis and 5 had posttraumatic arthritis. The main reasons for revision include glenoid loosening (7) instability (4) and peri-prosthetic fracture (2). The average constant scores post operatively for HHR and TSR were 35.5 (sd+/− 21.1) and 29.1 (sd+/− 12.1) respectively. The average ASES scores for HHR and TSR were 60.5(sd +/ 27.8) and 50.1(sd +/− 22.0) respectively. There was no statistical difference between the two groups in respect to the constant scores (p value 0.18) or ASES scores (p value 0.16). Overall, the pain relief was good post operatively following both HHR and TSR. The mean visual analogue score for pain following HHR was 3.2 and following TSR 3.5. Range of movement, function and strength was poor following both HHR and TSR.

HHR fail in a predictable way and can be revised with conversion to a TSR. TSR fail in a variety of ways and there revision surgery is demanding and complex. Both types of revision offer good pain relief but poor function.

Purpose of Study: To compare the mechanical performance of two commonly used arthroscopic slip knots with that of a hand tied control.

Methods: The arthroscopic slip knots assessed were the Duncan Loop (DL) and the Tautline Hitch (TLH), both of which were tied with arthroscopic knot pushers and secured with Three Reversing Hitches on Alternating Posts (RHAPs). These were compared with four hand tied throws of a squre knot. All three knots were tied using three different materials: number two Ethibond, number one PDS and number two Fiberwire. All knots were tied in a close loop configuration between two metal bars mounted on an Instron materials testing device and pulled apart to both clinical and ultimate failure. Clinical failure was defined as the force in Newtons (N) required to increase loop length by three millimetres, which equtes in vivo with a critical loss in apposition of repaired tissues. Ultimate failure was defined as the force in N resulting in complete slippage or breakage of the knot being tested. This study was different than those before it in that a much larger number of each knot/suture permutation was tested (thirty in each case) to give the study sufficient power to detect significant differences between the knots tested.

Results and Conclusion: Based on the findings of this study, it is our recommendation that an arthroscopic TLH slip knot secured with three RHAPs and tied using a number two Fiberwire suture be used to produce shoulder repairs that are equivalent if not superior to those achieved using open hand tied methods.