Introduction: The use of freeze-dried grafts in the treatment of knee instability is a common technique used in rescue surgery of complex knee instabilities.

Purpose: To assess the evolution of patients that undergo complex knee surgery with freeze-dried ligaments.

Materials and methods: We carried out a retrospective study of patients that had undergone knee ligament surgery with freeze-dried grafts between 1999 and 2005. The study was carried out on 89 patients with a minimum follow-up of 18 months. They were all men except for 3 women. The patients were all of working age, from 19–51 years of age. Fifty-five patients underwent ACL surgery due to tears of previous plasties of the semitendinosus and rectus femoris muscle tendons, with an associated meniscectomy during the first operation in most patients. There were isolated posterior cruciate ligament tears in 5 cases and 29 cases of combined instabilities. In almost all cases preoperative Rh is carried out. Patients were immobilized for a period of 2–4 weeks according to the plasty performed. We assessed the patients using the Lyshom scale, VAS scale, MRI at 1 year, x-rays, range of movement, stability and return to normal work and sports activities.

Results: We assessed the results in patients that underwent ACL rescue surgery and obtained the following results: 44% of the patients reported a subjective feeling of instability and up to 15% required repeat stabilization surgery. In those patients for whom an MRI was obtained it was possible to see 29% of plasty resorption. On x-ray a significant increase in the size of the tibial tunnel and permeability was seen in comparison with autologous series. Good postoperative mobility results were obtained. Seventy percent of the patients were able to return to their previous work activity and 44% continued practicing their customary sports activities. Complications: During the postoperative period recurrent effusions were seen in 41% of the patients, which resolved spontaneously in most cases. There were 2 cases of postoperative septic arthritis that required surgical action.

Conclusions: In our series of freeze-dried plasties we had a high rate of complications and graft resorptions which were clearly higher than those of other published series where other types of grafts were used.

Purpose: To analyze the causes of repeat knee arthroscopy in the same knee.

Materials and methods: We reviewed 923 patients that had undergone knee arthroscopy during 2005 and assessed those that had already undergone previous arthroscopy of the same knee that year or in previous years and analyzed the causes.

Results: Of the 923 patients that required knee arthroscopy 169 (18.3%) had undergone previous surgery. Four (2.3%) had undergone 3 previous arthroscopies, 27 (15.9%) two and 138 (81.6%) one. In 59.8% of cases, the symptoms that led to repeat arthroscopy were non-traumatic continuous pain. The other cases required repeat arthroscopy due to new trauma, or meniscal or anterior cruciate ligament (ACL) tears. The patients with affected menisci (104) underwent partial meniscectomy, 31% had a posterior cruciate ligament (PCL) tear and 58% had menisci remains with or without osteochondral lesions.

Repeat arthroscopies of ACL tears treated by ligamentoplasties (41) were due to plasty tears in 46% of cases and adhesions in 27%. In patients that underwent 3 arthroscopies, the main diagnosis was plasty tear in 45% of the total sum of 2^nd and 3^rd arthroscopies. Mean time between first and second arthroscopy was 28 months and between second and third arthroscopy 12 months.

The relative risk of undergoing a new arthroscopy during the same year as meniscectomy was 1.12% and as ACL ligamentoplasty 0.95%.

Conclusions: Not all repeat arthroscopies are caused by previous complications. The main clinical reasons for a repeat arthroscopy can be traumatic or non-traumatic, with a greater frequency of the latter. We found that the risk of repeat arthroscopy was greater during the first year in meniscal tears than in ACL tears.