Introduction: Accelerated rehabilitation programs following ACL reconstruction require adequate fixation strength. Staple fixation of grafts outside the tibial tunnel has been shown to have fixation strength comparable to interference screws. The use of bioresorbable polymer implants has potentially significant advantages especially if revision is required. The purpose of this study was to evaluate a new bioresorbable fixation staple using an ovine model.

Materials and Methods: Forty-eight mature sheep underwent unilateral cranial cruciate ligament (CrCl) reconstruction. The reconstruction comprised a loop of superficial digital flexor tendon (autograft) joined to a prosthetic ligament (LK-15). Femoral fixation was by endobutton. Tibial fixation of the LK-15 was with either a new Poly-L-lactic acid (PLLA) staple (Zimmer Japan/Gunze Ltd.) or a Cobalt-chrome (CoCr) staple. Biomechanical and histological responses were evaluated at 0, 6, 12 and 24 weeks.

Results: At all times post-reconstruction there were no significant differences between staple types for construct strength or stiffness (p> 0.05). The staple was not the site of reconstruction failure, and there were no adverse tissue reactions, for either staple type. Fibrous tissue was more often found at the interface of the CoCr staple.

Conclusions: The PLLA staple performed biomechanically as well as the metal staple for tibial fixation of cruciate ligament reconstructions. There were no significant observable adverse histological responses over the time intervals examined.

We have determined whether somatosensory evoked potentials (SEPs) were detectable after direct mechanical stimulation of normal, injured and reconstructed anterior cruciate ligaments (ACLs) during arthroscopy. We investigated the position sense of the knee before and after reconstruction, and correlated the SEP with instability.

Reproducible SEPs were detected in all 19 normal ACLs and in 36 of 38 ACLs reconstructed during a period of 13 months. Of the 45 injured ACLs, reproducible SEPs were detected in 26. The mean difference in anterior displacement in the SEP-positive group of the injured ACL group was significantly lower than that in the SEP-negative group. In the reconstructed group, the postoperative position sense was significantly better than the preoperative position sense. Our results indicate not only that sensory reinnervation occurs in the reconstructed ACL, but also that the response to mechanical loads can be restored, and is strongly related to improvement in position sense.

For the purpose of investigating the effect of an insole with a lateral wedge, we studied 30 patients (31 knees) aged from 46 to 78 years with idiopathic osteonecrosis of the knee for at least three years. The 18 knees treated with an insole (group I) were matched by age, gender, obesity index, area of lesion, femorotibial angle, stage, and clinical evaluation with 13 treated conservatively without an insole (group II).

The clinical results, as rated by a knee score, improved significantly more in group I than in group II. Radiologically, the necrotic area and ratio decreased in group I, whereas in group II they increased. In advanced cases, with stage 4 or a femorotibial angle of more than 180°, the use of an insole did not improve the clinical or radiological findings. The insole is a valuable method of conservative treatment for the early stages of osteonecrosis of the medial femoral condyle.

We examined whether somatosensory evoked potentials (SEPs) were detectable after direct electrical stimulation of injured, reconstructed and normal anterior cruciate ligaments (ACL) during arthroscopy under general anaesthesia. We investigated the position sense of the knee before and after reconstruction and the correlation between the SEP and instability.

We found detectable SEPs in all ligaments which had been reconstructed with autogenous semitendinosus and gracilis tendons over the past 18 months as well as in all cases of the normal group. The SEP was detectable in only 15 out of 32 cases in the injured group, although the voltages in the injured group were significantly lower than those of the controls. This was not the case in the reconstructed group. The postoperative position sense in 17 knees improved significantly, but there was no correlation between it and the voltage. The voltage of stable knees was significantly higher than that of the unstable joints. Our findings showed that sensory reinnervation occurred in the reconstructed human ACL and was closely related to the function of the knee.