Introduction and Aims: To deliver osteogenic cells into bone defects, the crucial steps are cell attachment and migration in cell-delivery biomaterials. The aim of this study was to examine whether complexes comprised of vitronectin (VN), insulin growth factors (IGFs) and insulin growth factor binding proteins (IGFBPs) could enhance human osteoblasts attachment, especially cell migration in three-dimensional (3-D) culture.

Method: Human osteoblasts derived from alveolar bone chips (passage 4–10) and established human osteoblast cell line SaOS-2 were used. These cells were seeded on scaffolds of type I collagen sponges and poly glycolic acid (PGA) (approx. one millimetre thick, porous structure), which had been coated with VN +/− IGF-I +/− IGFBP-3. Cell attachment and migration were evaluated by cell counting, confocal microscopy, and scanning electron microscopy.

Results: The number of attached human osteoblasts was significantly higher in wells in which pre-bound VN was coated on the polystyrene culture dish or on type I collagen sponges. However, no significant difference of cell attachment was observed when growth factors were bound to these surfaces in the presence of VN. In the two scaffold materials examined, greater cell attachment was found in type I collagen sponges compared to PGA scaffolds. However, coating the scaffolds with complexes comprised of VN + IGF-I or VN + IGFBP-5 + IGF-I enhanced cell attachment on PGA. Moreover, the presence of vitronectin + IGF-I + IGFBP-5 resulted in significantly greater osteoblast migration into deep pore areas as compared to untreated scaffolds or scaffolds treated with different combinations of the VN +/− IGF +/− IGFBP-5.

Conclusion: Complexes of VN + IGFBP-5 + IGF-I enhance the attachment and migration of human osteoblast in three-dimensional culture, which implies that this complex has potential application for use in surface modification of biomaterials for tissue reconstruction.

Introduction Malpositioning of cup and stem in total hip replacement can result in significant clinical problems such as dislocation, impingement, limited range of motion and increased polyethylene wear. The use of mechanical alignment guides for correct cup positioning has been shown to result in large variations of cup inclination and version.

Methods Bilateral total hip replacements were performed in twelve human cadavers. While in each cadaver the operation on one side was performed with the aid of a non image based hip navigation system, the cup positioning at the contralateral hip was controlled by use of a conventional mechanical alignment guide. Post-operative cup position relative to the pelvic reference plane was assessed in both groups by the use of a 3D digitizing arm.

Results By aiming for 45° inclination and 20° anteversion for cup position the median inclination was assessed as 45.5° for the navigated group and 41.8° for the control group. Median anteversion in the navigated group was calculated as 21.9° and 24.6° for the control group. The 90 percentile showed a much wider range for the control group (36.1° to 51.8° inclination, 15° to 33.5° anteversion) than for the navigated group (43.9° to 48.2° inclination, 18.3 ° to 25.4° anteversion).

Conclusions The cadaver study demonstrates that computer assisted cup positioning using a non-image based hip navigation system allowed a more precise placement of the acetabular component in the surgeon’s desired orientation with less variance than in the control group.

In relation to the conduct of this study, one or more the authors have received, or are likely to receive direct material benefits.

Introduction Malposition of the acetabular component in total hip arthroplasty is associated with a number of significant complications. In this study we acertain the accuracy of an imageless computer based surgical navigation system for positioning the acetabular component, using a mechanical hip device.

Methods A mechanical hip device was constructed that allowed accurate measurement of inclination and version, leg length and lateral offset of the acetabular and femoral components. In 31 cases these parameters were varied while a blinded operator would place the cup in the predetermined position in the mechanical hip jig. The values given by the navigation system on the screen were recorded and compared to the measurements obtained directly from the mechanical hip device.

Results The mean difference between value set by an independent person and value read by the navigation system was; inclination of the cup 0.97 ± 0 and the ante-version of the cup 1.58 ± 0.83. The leg length change contributed by the cup showed a mean difference between beforehand set value and read value on the screen of 1.48 ± 1.36 mm and for lateral offset change by the cup of 1.58 ± 0 mm.

Conclusions The accuracy of the hip navigation unit demonstrated in this study is well within the limits that would be required for clinical usage as a surgical aid in total hip arthroplasty and could provide the surgeon with a tool that enables significant improvement in accuracy for acetabular positioning.

Introduction Minimally invasive surgery (MIS) for THR may accelerate rehabilitation. The objectives of this study were to determine the effect of three surgical approaches (standard, mini [< 10 cm], Stryker two incision approach [MIS]) on length of stay, rehabilitation rates, clinical outcome, quality of life, patient safety, complications and implant position.

Methods Each surgeon completed six to eight documented cases using the MIS technique before commencing enrolment to eliminate any learning curve effect. Prior to enrolment patients were assessed for eligibility and provided signed informed consent. Patient demographics, medical histories and surgical details were collected. Post-operative rehabilitation was independently documented by a physiotherapist. Clinical evaluations (HHS) were collected pre-operatively, 10 days, six weeks, three months and one year. Patient outcomes (SF12/WOMAC) were collected pre-operatively and at one year. Radiological evaluations were completed at six weeks. CTs/x rays were subject to an independent review.

Results A sample size of 48 patients was determined based on the primary objective - length of stay. Enrolment commenced at the end of 2002 and these results are based on the first cohort of patients; based on current recruitment rates, the authors anticipate that the majority of patients will be enrolled by presentation time. Preliminary results show mean incision lengths (cm) of 3.5/5.8 for the two incision MIS compared to 8.8 and 13.5 for the mini and standard respectively. Mean duration of surgery (mins) was 79 (MIS), 62 (mini) and 42 (standard). The median time (hours:minutes) from end of surgery until the first episode of knee flexion > 45°, straight leg raise, active abduction, standing, out of/in to bed, stair climbing and walking > 20 metres was shortest for MIS compared to mini and standard surgical approaches. The maximum distance walked was greatest for the MIS group. The mean length of stay (days) was shortest for the MIS group, 2.5 compared to 4.7 (mini) and 3.7 (standard). Mean blood loss (cc) was greatest for the MIS group, 667 compared to 525 (mini) and 467 (standard). There were no intra/post-operative complications or blood transfusions.

Conclusion Results suggest accelerated rehabilitation, decreased hospital stay and increased surgery duration for the MIS group. There are no safety concerns, however the procedure is felt to be quite technically demanding requiring an appropriate level of training/experience. The authors believe this is the only controlled study of this nature currently being conducted internationally.

In relation to the conduct of this study, one or more of the authors has received, or is likely to receive direct material benefits.