Background: A common question asked by patients who have undergone knee arthroplasty is whether they will activate the security scanners at airports. This has become a greater issue for the patient in the post 9/11 era.

This study surveys our patients to determine their experiences at airport security, establishes the detectability of common orthopaedic implants in an airport security scanner

Materials and Methods: A survey of a single surgeon series of knee arthroplasty patients was conducted to ascertain the frequency with which they activated airport security scanners. Their experiences were documented and their preferences for identification were ascertained.

A volunteer with metal implants strapped on and patients with implants in-situ walked through a gate scanner at a UK airport. Also, standard operating procedures at UK airports were ascertained.

Results: 150 patients were surveyed. 61 male, 89 female with an average age of 71 years.

There were 111 total knee replacements (TKR), 20 unicompartmental knee replacements (UKR), 2 bilateral UKR replacements, 17 bilateral TKR.

Unlike previous studies from the U.K., virtually all patients with a TKR activated the gate scanner. Conversely, those with unicompartmental replacements did not.

Patients are concerned about this possibility but are not informed at time of surgery and do not know what the procedures are if their implant is detected.

The patient with the bilateral UKR did not set off the scanners where as the patient with the TKR did.

A variety of surprisingly large trauma implants escaped detection.

Conclusion: In contrast to previous work this study demonstrates that patients with TKR do activate the scanner, possibly due to heightened security. Other implants do to a variable extent. Patients are concerned about this possibility and should be made aware both of this and the further checks to which they will be exposed. Our survey demonstrated differences in how passengers with metal implants are screened by airport security around the World and particularly in the United States. In line with the International Air Transport Association (IATA) we propose the development of a more harmonised approach to screen international travellers.

We have carried out a prospective study comparing the results at five years in patients older than 75 years of age undergoing hydroxyapatite-coated, cementless total knee replacement (TKR) with those who were younger. The Knee Society clinical rating scores were recorded before and after operation. Of 559 patients undergoing TKR, 135 were in the elderly age group. The knee scores at five years or more showed comparable results, with patients under 75 years of age reaching a score of 183 and those aged 75 years or over reaching 174. These differences were predominantly due to the functional component of the score. We conclude that elderly patients do just as well as the younger group using this prosthesis.

Although hydroxyapatite (HA) coating is known to enhance fixation in THR, its role in the fixation of Total Knee Replacements is less well appreciated. This study was performed to assess the medium-term results of an HA-coated TKR.

Between August 1992 and 1998 all patients requiring a primary TKR were treated with a hydroxyapatite-coated, PCL-retaining prosthesis implanted by the senior author. The HA coating used was 70 microns thick with 75% crystallinity and 20% porosity. It is deposited on a beaded heat-sintered surface. A combined Hospital for Special Surgery and Knee Society Score was recorded pre-operatively and at three, six, 12, 24 and 60 months post-operatively. Fluoroscopically-controlled interface views were performed on the first 161 knees immediately post-operatively and repeated 24 months postoperatively.

Six hundred and ninety two patients (Male:Female 335:357) with a mean age of 68 years (31–88 years) underwent 1 000 TKR mainly for OA (93%) and inflammatory arthropathies (RA 3%, psoriasis 1%). The mean follow up was 75 months (40–115). There were 461 unilateral (R:L 256:205) and 539 bilateral replacements (462 simultaneous and 77 staged).

The pre-operative knee score was 95/200, ROM 6–115 degrees and at latest review was 182/200, ROM 1–113 degrees.

Forty four patients have died (mean age 73 years, range 54 to 88). There have been 14 deep infections (1.4%), 22 proven pulmonary emboli (2.2%) and five periprosthetic fractures (0.5%). Six revisions have been performed. Visible gaps between bone and implant were present in 91% of femora and 58% of tibiae initially and in 6% of femora and 8% of tibiae at two years on interface views. There have been no cases of clinical loosening.

Currently, this study comprises the largest known series of HA-coated total knee replacements. These results demonstrate that HA appears to enhance fixation of uncemented knee prostheses which maintain good clinical outcomes.

From a prospective, cross-sectional survey of 402 patients who had a total hip (THR) or a total knee (TKR) replacement for idiopathic osteoarthritis (OA) at a major centre, we determined the prevalence of these replacements for idiopathic OA in their 1171 siblings and 376 spouses. Using spouses as controls, the relative risk of THR in siblings was 1.86 (95% CI 0.93 to 3.69). The relative risk for TKR in siblings v spouses was 4.8 (95% CI 0.64 to 36.4) whereas the risk for the combined outcome measure of THR or TKR was 2.32 (95% CI 1.22 to 4.43) when siblings and spouses over 64 years of age were compared. Using a threshold liability model (Falconer), the heritability of end-stage OA of the hip was estimated at 27%.

The increased risks of joint replacement for severe, idiopathic OA which we found in siblings suggest that genetic influences are important in end-stage OA of the hip and knee.