To evaluate prospectively the mid-term results of the Zimmer Unicondylar Knee arthoplasty (UKA).

Between 2005 and 2012, 187 unicompartmental knee arthroplasties (UKA) were performed by a single surgeon using a fixed-bearing prosthesis (Zimmer). 37 cases were excluded as either were lost to follow-up or had less than six months follow-up. The study included 150 UKAs. Deformity, if present, was correctable. Patellofemoral joint (PFJ) disease was not considered as an absolute contraindication. The average patient age at the time of surgery was 66 years (range 42–88 years); 78 of which were male. Mean follow-up time was 3.6 years (range 7–81 months). Mean Body Mass Index (BMI) was 29 (range 21–41). Clinical and conventional radiological evaluations were carried out at six months, one, two and five years postoperatively.

147 cases were medial compartment replacement and three were lateral. 86 patients had grade III OA and 64 had grade IV (Kellgren and Lawrence). 113 patients had an element of PFJ disease. The mean Knee Society knee and function scores had an improvement from 55 and 54 points pre-operatively to 95 and 94 points respectively at time of most recent evaluation. The average flexion improved from 116 degrees pre-operatively to 127 degrees. Two cases were revised, one due to progression of osteoarthritis in the lateral compartment of the knee and the other was due to arthrofibrosis.

The Zimmer unicompartmental knee arthroplasty provided excellent pain relief and restoration of function in carefully selected patients. However, long-term studies are necessary to investigate the survival rate for this prothesis.

Total hip-joint arthroplasty is associated with a high rate of perioperative blood transfusion, which increases the risk of blood-borne disease, anaphylactic and haemolytic reactions. Devices are used which collect and allow the re-infusion of blood lost during surgery, with the aim of reducing allogenic blood transfusion requirements. The purpose of this study was to establish whether the use of a ‘cell-saver’ device reduces the risk of post-operative allogenic blood transfusion in total hip joint arthroplasty.

All total hip arthroplasties performed by a single surgeon over a twelve month period were divided into two cohorts of patients; one which used an intra-operative cell saver device, the other which did not. Data was collected for patient demographics, pre-operative blood tests and blood loss, with the outcome measure as post-operative transfusion requirements. The total number of patients was 233; 166 primaries, 33 resurfacing & 20 revision arthroplasties: 14 excluded for insufficient data.

Comparison of the two cohorts (intra-operative cell saver used vs. no cell-saver used), demonstrated no significant difference in the post operative blood transfusion requirements for patients undergoing primary total hip joint arthroplasty (n=166, 18.3% vs. 11.0%, p=0.08), Birmingham resurfacing arthroplasty (n=33, 5% vs. 7.7%, p=0.49), and revision arthroplasty (n=20, 28.6% vs. 50%, p=0.26). There were no significant differences demonstrated between the patient demographics of the two cohorts for any of the groups. In the cell-saver cohort, the average volume of blood re-transfused was 117mls per patient (range 0 – 400mls).

Intra-operative use of cell-saver devices does not decrease post-operative transfusion requirements in primary hip arthroplasty. A larger size study is required to assess the outcome in resurfacing and revision hip arthroplasty surgery.

Introduction: Total hip-joint arthroplasty is associated with a high rate of peri-operative blood transfusion, which has associated risk. Previous studies have identified individual factors than can predict those patients most at risk of post-operative allogenic blood transfusion. We undertook this study to attempt to identify further factors that may predict post-operative blood transfusion.

Methods: Data was collected pre-operatively for patient demographics including type of surgery, sex, age, BMI, ASA, pre-operative haemoglobin & pre-operative packed cell volume for all total hip arthroplasties performed by a single surgeon over twelve months (Total number 233; 166 primaries, 33 resurfacing & 20 revision arthroplasties: 14 excluded for insufficient data). Post-operative data collection included post-operative haemoglobin levels and allogenic transfusion requirements.

Results: Of 166 patients who underwent primary hip arthroplasty, 25 (15.1%) received allogenic blood transfusions, an average volume of 2.1 units per patient transfused. Analysis revealed significant predictive factors of gender (females > males, p=0.0019), advancing age (p=0.0045), lower height (p< 0.0000), lower pre-operative weight (p=0.0010), lower pre-operative haemoglobin (p< 0.0000), and lower pre-operative packed cell volume (p< 0.0000). Patients who underwent revision surgery were also more likely to have undergone transfusion compared to both primary (6.1% transfused, p=0.025) and resurfacing arthroplasty (35% transfused, p=0.009). BMI and ASA were found to not be significant risk factors. Pre-operative packed cell volume (PCV) showed the strongest correlation with post-operative blood transfusion. Cases with a PCV below the average of 39% had a rate of transfusion of 28%, 6.4 times greater than for those patients above the average at 4.4% (p< 0.0000).

Discussion: Pre-operative measurements of height, weight, haemoglobin and packed cell volume, together with factors including sex & type of surgery can identify those patients who are at greater risk of post-operative transfusion allowing selective transfusion prevention strategies.

Following the discovery of a powerful venous pump in the foot that is activated by weight-bearing independently of muscular action, a pneumatic impulse device was developed to actuate this pump artificially. In a multicentre international trial the device was shown to reduce post-traumatic and postoperative swelling; pain also was alleviated. Evidence is also presented that dangerously high compartment pressures may be reduced to acceptable levels and fasciotomy avoided. We present an explanation of the clinical effects of activation of the venous footpump, based on recent improved understanding of the physiology of the microcirculation. The hyperaemic response that follows the liberation of endothelial-derived relaxing factor (EDRF) by sudden changes of pressure after weight-bearing or impulse compression is particularly important.