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Biomedical subjects

Peter J Dobson

Publications and source records attributed to Peter J Dobson.

6 recordsLinked to original sources
PubMed2006

Patient-perceived outcomes and return to sport and work: TKA versus mini-incision unicompartmental knee arthroplasty.

Few reports have been published about patient-perceived outcomes and return to sport following total knee arthroplasty (TKA) compared with unicompartmental knee arthroplasty (UKA). This article compares the two procedures using self-assessment questionnaires to determine whether there was a difference in patient-perceived Oxford scores, return to sport, and return to work. Patient-perceived outcomes of mini-incision UKA (Oxford; Biomet Inc, Warsaw, Ind) and TKA were retrospectively reviewed at a minimum of 12 months after surgery. A total of 150 patients underwent 183 UKAs (mean age: 71.5 years; standard deviation [SD]: 9.85) and 120 patients underwent 142 TKAs (mean age: 71.53 years; SD: 9.87). Oxford knee questionnaires were used assessing modified Grimby score, sports, and work activities. Mean Oxford knee score (22.17; SD: 9.03) for UKA was superior to TKA (24.5; SD: 9.68) (P=.04) scores. Mean modified Grimby score for UKA (3.89; SD:1.27) was superior to TKA (2.76; SD:1.12) (P<.0001). More patients returned to or increased sports following UKA (P=.0003), but no sooner than TKA patients. Patient-perceived Oxford and modified Grimby scores were better and sporting activity was greater following mini-incision UKA compared to TKA.

Adult↗
PubMed2006

Optimized HREM imaging of objects supported by amorphous substrates using spherical aberration adjustment.

High Resolution Electron Microscopy (HREM) is often used to characterize objects supported by amorphous substrates, usually amorphous carbon. HREM is currently undergoing step change in performance due to aberration correctors. This paper examines the aberration corrected imaging of objects supported by amorphous substrates. In particular, we show that a substantial increase in the ratio of the object contrast to the substrate contrast can be achieved by utilizing the strong variation of phase contrast with height, which is present when the spherical aberration has been adjusted to a small value. This variation is examined using the familiar Weak Phase Object Approximation model from which it is determined that the contrast ratio achieves a maximum at a small nonzero value of the spherical aberration. This result is confirmed by multislice modelling which allows for deviations from the Weak Phase Object Approximation and delocalization effects. One important practical result of this study is the need to place the object of interest on the correct side of the amorphous carbon substrate.

Journal Article↗
PubMed2005

The effect of screw taper on interference fit during load to failure at the soft tissue/bone interface.

The effect of screw geometry on the pullout strength of an anterior cruciate ligament reconstruction is well documented. The effect of a truly tapered screw has not been previously investigated. Thirty bovine knees in right and left knee pairs were collected. Superficial digital flexors from the hind legs of sheep were harvested to form a quadruple tendon graft. For each knee pair, one tendon graft was fixed using a tapered screw (n=15) and the other with a non-tapered screw (n=15). Interference screws were manufactured from stainless steel, and apart from the tapered or non-tapered profile were identical. The screws were inserted into a tibial tunnel already containing the tendon graft. The interference fit was tested by extensile load to failure tests. The insertion torque of the screws and first sign of load to failure (by pullout) of the interference fit were recorded. Results were analysed using paired t-tests. The results indicated that tapered screws have significantly higher resistance to interference failure (p=0.007) and insertion torque (p<0.001) than non-tapered screws. The improved biomechanical performance of tapered screws demonstrated in this study may translate into superior clinical results, particularly at the tibial attachment of hamstring anterior cruciate ligament reconstruction, and also of hamstring fixation to the medial femoral condyle for patella instability.

Animals↗
PubMed2005

Effect of total knee arthroplasty on recreational and sporting activity.

BACKGROUND: Common concerns of patients undergoing total knee arthroplasty (TKA) are whether they can continue with certain recreational and sporting activities or even commence new ones after the procedure. The present study was designed to determine preoperative and postoperative activities, the numbers participating and the time to resume these activities. METHODS: Between 1 and 2 years after TKA, patients who had undergone 144 arthroplasties, were surveyed by postal questionnaire to ascertain how the arthroplasty had affected their recreational and sporting ability. Their preoperative and postoperative activity along with the time to resume was recorded. The Oxford knee score and estimate of physical activity was also collected. RESULTS: Out of the 144 TKA performed, 122 participated in sport and recreational activity preoperatively and 108 participated postoperatively. Patients stated that the surgery had a beneficial effect on their performance of sporting and recreational activities although the number of sporting events decreased. By multiplying individuals by the number of activities they participated in, there were 254 occurrences of sport and recreational activities preoperatively giving a mean for the group of 1.76 sports/patient. Postoperatively this had reduced to 204, giving a mean of 1.41. Three activities showed a significant change for individual patients from pre- to postoperation. Those which showed an increase were exercise walking, where 19 patients (13.2%) who did not walk before surgery took up walking afterwards (P < 0.006) and aqua aerobics, where five took up aqua aerobics postoperatively for the first time (P < 0.025). Golf was the only sport which had a significant fall in participation from pre- to postoperation, with 10 out of 19 golfers giving up (P < 0.025). CONCLUSION: The present study has shown that patients are adopting lower impact activities to participate in after TKA. The total number of patients performing a sport decreases postoperatively and the total amount of sport played decreases. These data will help to counsel patients.

Arthritis, Rheumatoid↗
PubMed2004

Effect of total hip arthroplasty on recreational and sporting activity.

BACKGROUND: Common concerns of patients undergoing total hip arthroplasty are whether they can continue with certain recreational and sporting activities or even commence new ones after the procedure. The present paper describes preoperative and postoperative activities, the numbers participating and the time to resume these activities. METHODS: Between 1 and 2 years after total hip arthroplasty, 216 patients, who had undergone a total of 235 arthroplasties, were surveyed by postal questionnaire to ascertain how the arthroplasty had affected their recreational and sporting ability. Their preoperative and postoperative activity along with the time to resume was recorded. A general hip score and estimate of physical activity was also collected. RESULTS: The number of patients participating in sport increased from 188 preoperatively to 196 postoperatively. Patients stated that the surgery had a beneficial effect on their performance of sporting activities although the number of sporting events decreased. By multiplying individuals by the number of sports they participated in, there were 434 occurrences of sport preoperatively giving a mean for the group of 1.9 sports per patient. Postoperatively this had reduced to 382, giving a mean of 1.7. Five sports showed a significant change for individual patients from pre to postoperation. Those which showed an increase were exercise walking, where 38 patients (16.8%) who did not walk before surgery took up walking afterwards (P < 0.0001) and aqua aerobics, where 15 took up this activity postoperatively for the first time (P = 0.002). There were three sports which decreased significantly from pre to postoperation. They were, golf where 13 out of 39 (P = 0.005), tennis 13 out of 14 (P = 0.01) and jogging where six out of seven (P = 0.01) patients stopped participating. CONCLUSION: This study has shown that patients are adopting lower impact activities to participate in after total hip arthroplasty. The total number of patients performing a sport increases postoperatively but the total amount of sport played decreases. These data will help to counsel patients.

Aged↗