Purpose

In stabilisations of atlantoaxial instabilities it holds risks to injure the A. vertebralis as well as neurological structures. Furthermore the posterior approach of the upper part of the cervical spine requires a huge and traumatic preparation of the soft tissue. However the anterior transarticular C1-2 fusion (ATF) is less traumatic and offers almost the same strengh of the stabilisation.

Introduction: Selective COX-2 (Cyclooxygenase-2) inhibitors have been found to impede fracture healing. The effect of selective COX-2 inhibitors on tendon healing in a bone tunnel, however, is unknown.

Methods: The authors performed bilateral anterior cruciate ligament reconstructions in 32 rabbits and used peripheral quantitative computed tomography (pQCT) to compare tendon-to-bone healing between tunnel aperture and midtunnel regarding bone mineral density (BMD) and ingrowth of new bone. Each animal was assigned to one of four groups. Two groups received selective COX-2 inhibitors orally for 3 weeks (Cele-coxib; 10 mg/kg/d), the two other groups received no COX-2 inhibitors (controls). The animals were sacrificed 3 and 6 weeks after surgery. In biomechanical testing maximum load to failure and stiffness of the tendon grafts were calculated from the load displacement curve and failure modes were recorded. To assess indirectly the effect on local COX-2 activity the synovial content of Prostaglandin E2 (PGE2), the major metabolite of arachnidonic acid metabolism and catalyzed by COX-2, was measured by Enzyme-linked Immunosorbent Assay (ELISA).

Results: Animals treated with selective COX-2 inhibitors had significantly lower BMD at the tunnel aperture (P=.02). In all groups the BMD at the tunnel aperture was significantly higher in comparison with the midtunnel (P< .05). In the controls ingrowth of new bone was greater at the tunnel aperture at 3 weeks (P=.028). After 3 weeks of COX-2 inhibitor administration synovial fluid concentrations of PGE2 were significantly lowered (P=.018) and increased more than threefold by 6 weeks after surgery and 3 weeks after last drug administration (P=.022), while in the controls there was a decrease in PGE2 between week 3 and 6. At 6 weeks the controls exhibited a twofold increase in maximum load to failure (3 weeeks: 28.2±20.9 N; 6 weeks: 59.6±53.6 N; P=.394), whereas the COX-2 inhibitor treated specimens decreased 1.9fold (3 weeks: 69.3±50.5 N; 6 weeks: 37.4±16.8 N; P=.24). Maximum load to failure values correlated with PGE2 changes, but not statistically significant (r²= −0,502; p=0,056). Failure modes at 3 and 6 weeks were rupture and degloving, respectively, of the tendon graft.

Discussion: This study revealed decreased bone mineral density at the tunnel aperture at 3 weeks, an increase of the inflammatory mediator PGE2 and decreased graft stability with time after treatment with selective COX-2 inhibitors. Untreated controls appeared to have a more physiological healing course with a continuous decrease in PGE2 and an increase in graft stability. Our results suggest, that selective COX-2 inhibitors may delay tendon healing in a bone tunnel.

Navigation during the positioning of the acetabular component in total hip replacement is a promising tool to improve the prosthetic alignment. Correct placement of the cup will reduce the risk of mechanical complications such as dislocations and impingement. All navigation systems, be they CT or infra-red based, require exact determination of the symphysis and both anterior superior iliac spines, the landmarks of the patient’s pelvis. The accuracy of the intraoperative palpation of these landmarks influences the outcome of the cup-angulation more than any other factor.

Our experience in over 700 infra-red based navigated total hip replacements since 2002, shows a wide variation of acetabular cup anteversion. This study was intended to prove a correlation between the subcutaneous fat thickness and infra-red based measurements of the pelvis.

The navigation system (PiGalileo) used in this study is infra-red based, using the symphysis and both anterior superior iliac spines as reference points.

To determine the influence of the surgeons’ experience in palpating the landmarks on the outcome of the position of the acetabular cup, two series of 10 consecutive THRs were performed by a single surgeon. The first series was performed after the navigation had been introduced into the routine of our total hip replacements and the initial learning curve had passed. The second series was initiated to prove a correlation between the patient’s soft tissue cover and acetabular cup anteversion. The subcutaneous tissue overlying the landmarks was measured preoperatively by ultrasound. The computer calculated anteversion was corrected by a factor based on the clinical experience of the surgeon. In both series coronal tilt and cup anteversion were evaluated via post-operative CT-scans. Thus determined, the position of the cup was compared to the intraoperative measurements of the navigation system.

All acetabular cup angles were kept within the required limits. In the first series, the mean difference of the measurements of the coronal tilt and anteversion were 3.8° and 7.2° respectively. In the second series, the mean difference of the anteversion was improved by 2°. There was no change affecting the coronal tilt. In both series, the operating time was increased by 9 minutes compared to conventional THRs.

Precise landmark acquisition is essential in order to profit from navigation in total hip replacement and obtain a cup angulation far superior to conventional placement. The correlating factor of subcutaneous fat and cup anteversion has yet to be determined.

Introduction: Navigation during the positioning of the acetabular component in total hip replacement is a promising tool to improve the prosthetic alignment. Correct placement of the cup will reduce the risk of mechanical complications such as dislocations and impingement. All navigation systems, be it CT or Infrared based, require exact determination of the symphysis and both anterior superior iliac spines, the landmarks of the patient’s pelvis. The accuracy of the intraoperative palpation of these landmarks influences the outcome of the cup-angulation more than any other factor.

Aim of this study: Our experience in over 350 infrared based navigated total hip replacements since 2002, showed a wide variation of acetabular cup anteversion. This study should prove a correlation between the subcutaneous fat thickness and infrared based measurements of the pelvis.

Material and Methods: The navigation system (PiGalileo) used in this study is infrared based, using the symphysis and both anterior superior iliac spines as reference points.

To determine the influence of the surgeons experience in palpating the landmarks on the outcome of the position of the acetabular cup, two series of 10 consecutive THRs were performed by a single surgeon. The first series was performed after the navigation has been introduced into the routine of our total hip replacements and the initial learning curve had passed. The second series was initiated to prove a correlation between the patient’s soft tissue cover and acetabular cup anteversion. The subcutaneous tissue overlying the landmarks was measured preoperatively by ultrasound. The computer calculated anteversion was corrected by a factor based on the clinical experience of the surgeon. In both series coronal tilt and cup anteversion were evaluated via post-operative CT-scans. The so determined position of the cup was compared to the intraoperative measurements of the navigation system.

Results: All acetabular cup angles were kept in the required limits. In the first series the mean difference of the measurements of the coronal tilt and anteversion were 3.8° and 7.2° respectively. In the second series the mean difference of the anteversion was improved by 2°. There was no change affecting the coronal tilt. In both series the operating time was increased by 9 minutes compared to conventional THRs.

Conclusion: Precise landmark acquisition is essential in order to profit from navigation in total hip replacement and obtain a cup angulation far superior to conventional placement. The correlating factor of subcutaneous fat and cup anteversion has yet to be determined.

Objectives: The replacement tissue used for anterior cruciate ligament reconstruction undergoes extensive biologic remodelling and incorporation after implantation. These changes, in which the tendon loses some of its characteristic features and adopts those typically associated with ligaments, has been referred to as ligamentization. The purpose of this study was to identify the proinflammatory response in the healing graft in the early phase.

Methodes: Twenty New Zealand White Rabbits underwent ACL reconstruction with a semitendinosus tendon. Animals were sacrificed at 3 and 6 weeks. The harvested tissue including parts of remaining grafted tendon and genuine anterior cruciate ligament at time of the surgery as well as the tendon graft withdrawn at sacrification were prepared for immunohistochemical, histomorphometry and electromicroscopical analysis; synovia samples were taken at the sacrification as well. The tissues were immunostained for IL-1beta, TGF-beta, TNF-alpha (induction of inflammatory cascade), COX-2 (mediator of inflammatory response), Matrix Metalloproteinases (MMP-1, MMP-3, MMP-13, matrix destructive enzymes), TIMP-2 (Tissue Inhibitor of MMPs); the PGE2 (mediator of inflammatory response) content in the synovia was quantified by ELISA.

Results: At 3 weeks after surgery the COX-2+ cells accounted for 70% of all cells present in the graft tissue, and decreased to 28% at 6 weeks. Similar, IL-1beta+ cells within the tendon decreased from week 3 to week 6. Controversly, there was an increase of COX-2, IL-1beta and MMP-1 in the intercellular tissue. The numbers of COX-2+ cells and IL-1beta+ cells at 3 weeks as well as the intercellular area stained positiv for COX-2, IL-1beta and MMP-1 at 6 weeks were significantly larger compared to the genuine ACL (p =< 0.05). At 3 weeks some cells stained positiv for MMP-3 and MMP-13, but not at 6 weeks. There was a slight pericellular staining for TIMP-2 at 3 weeks. TGF-beta+ cells and TNF-alpha+ cells were almost not detectable at every time point. Thus, proinflammatory cytokines and MMPs were synthesized in the early phase after ACL reconstruction by the tendon cells and accumulated at 6 weeks in the intercellular tissue.

Conclusions: In the early phase of the graft healing after ACL reconstruction, there was a signifikant increase in proinflammatory cytokines and matrix destructive enzymes in the tendon graft. With the capability of synthesizing cytokines, tendon cells may play a critical role in tendon healing at early time points. Facing the widespread use the bias of cox-2 inhibitors on these immunologic processes has to be checked. Activating matrix destructive enzymes, cytokines appear to be crucial for connective tissue remodelling and graft stability after ACL reconstruction.