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This study reports a technical approach used in the application of computer-assisted navigation for patients undergoing a medial opening wedge proximal tibial osteotomy. Alignment of the limb can be monitored and documented at the beginning, during, and end of surgery. Surgical incisions are 4-6 cm in length and operative time (including the intra-articular arthroscopic procedure and osteotomy) averages 68 minutes, with 12 seconds of total fluoroscopy using a mini C-arm. Follow-up radiographic assessment in the office setting confirms corrections within 2 degrees of the planned correction. Computer-assisted navigation is a valuable adjunct during opening wedge proximal tibial osteotomy as it provides real-time intraoperative information that contributes to and confirms decision-making.

Background: To achieve their potential therapeutic benefit, hyaluronic acid derivatives should be injected directly into the knee joint space and not into the anterior fat pad or the subsynovial tissues. In the absence of a knee effusion, reproducible needle placement into the intra-articular space presents a challenge to the clinician., Methods: The accuracy of needle placement was assessed in a prospective series of 240 consecutive injections in patients without clinical knee effusion. The injections were performed by one orthopaedic surgeon using a 2.0-in (5.1-cm) 21-gauge needle through three commonly employed knee joint portals: anteromedial, anterolateral, and lateral midpatellar. Accuracy rates for needle placement were confirmed with fluoroscopic imaging to document the dispersion pattern of injected contrast material., Results: Of eighty injections performed through an anterolateral portal, fifty-seven were confirmed to have been placed in the intra-articular space on the first attempt (an accuracy rate of 71%). Sixty of eighty injections performed through an anteromedial approach were intra-articular on the first attempt (75% accuracy rate), as were seventy-four of eighty injections performed through a lateral midpatellar portal (93% accuracy rate)., Conclusions: Using real-time fluoroscopic imaging with contrast material, we demonstrated the difficulty of accurately placing a needle into the intra-articular space of the knee when an effusion is not present. This study revealed that a lateral midpatellar injection (an injection into the patellofemoral joint) was intra-articular 93% of the time and was more accurate than injections performed by the same orthopaedic surgeon using either of the other two portals. This study highlights the need for clinicians to refine injection techniques for delivering intra-articular therapeutic substances that are intended to coat the articular surfaces of the knee joint.

Bioabsorbable screws composed of poly(L-lactic acid) (PLA) were used for graft fixation and studied prospectively with serial magnetic resonance imaging (MRI) scans at 8, 16, and 24 months after autogenous patellar tendon anterior cruciate ligament (ACL) reconstruction in 10 patients. Conventional spin echo, proton density, and T2-weighted double echo sequences were obtained, as well as T2-weighted fat-saturated fast spin echo sequences. All but one of the screws (19 of 20) were evident in all serial scans. These showed minimal decrease in size over time. The one screw that had completely disappeared 8 months after reconstruction had cracked during insertion. None of the reconstructed ACL grafts showed clinical instability, persistent effusions, or detectable adverse reactions to the screws. Two patients developed abnormal signal in the tibial tunnel: one developed fluid anterior to the graft, and the other developed increased signal within the graft. The abnormal signal resolved with time in both patients. Other than the preceding changes, no abnormalities were detected on conventional sequences. Fat-saturated fast spin echo sequences showed a variable amount of increased signal around the tunnels, suggesting edema or fibrovascular marrow changes. The changes noted near the tunnels on the fat-suppressed scans most probably represent a general reaction to surgical insult rather than a reaction to the bioabsorbable screws, as similar changes were noted at the patellar harvest site.

In reconstructing the ACL, ideal tibial tunnel placement requires an understanding of the unique anatomy of the ACL tibial footprint and its relationship to the PCL, lateral meniscus, and medial tibial part of the spine. In addition to precise placement of the tibial tunnel, its length and angulation are factors to consider. Using consistent anatomic landmarks with attention to detail, the tibial tunnel can be reproducibly placed in a manner that is not detrimental to the graft.

The fate of donor cells in fresh allografts of the patellar and anterior cruciate ligaments was assessed after transplantation of the allografts as substitutes for the anterior cruciate ligament in goats. DNA-probe analysis was used to distinguish between the DNA of individual goats. Donor DNA was completely replaced by recipient DNA in both the transplanted patellar and anterior cruciate ligaments within a four-week period. Simultaneous full-thickness skin transplants in the same animals were not rejected during the interval of rapid loss of donor DNA from the allografts. The absence of rejection of the skin grafts at the one-week interval suggests that no pre-existing antibody associated with an immune reaction was responsible for the rapid loss of DNA in the allografts.

Arthrofibrosis is one of the recognized complications following traditional anterior cruciate ligament (ACL) reconstruction. With the advent of arthroscopic assisted ACL reconstructions, the extent of potential arthrofibrosis appeared to be less. However, 13 patients after intra-articular ACL reconstruction using a patella tendon autograft developed a similar symptom complex. In addition to postoperative loss of full extension, there was an audible and palpable clunk with terminal extension. These patients had similar arthroscopic findings of a nodule that formed anterolateral to the tibial tunnel placement of the graft. The arthroscopic appearance of the soft tissue mass with its surface vessels was reminiscent of a "cyclops." After arthroscopy with debridement and manipulation of the knee, extension was improved in all cases. The average range of motion immediately after the procedure was 6.0-130 degrees, compared with 16-103 degrees preoperatively. The range of motion at last follow-up averaged 3.8 degrees of extension and 138 degrees of flexion. All patients had greater than 130 degrees of flexion. There were no complications attributed to the manipulation and arthroscopic lysis of adhesions, and no patient experienced loss of graft integrity or knee stability. The "cyclops" nodule was examined grossly and microscopically and demonstrated peripheral fibrous tissue with a central region of granulation tissue in all specimens. In addition, two specimens were noted to include bony fragments and three specimens contained cartilaginous tissue.

One hundred nine patients over a 3 year period underwent reconstruction for chronic ACL ruptures using a freeze-dried, ethylene oxide-sterilized bone-patella tendon-bone allograft. Seven patients (6.4%) developed a characteristic persistent intraarticular reaction. This reaction was characterized by persistent synovial effusion with collagenous particulates and cellular inflammatory response. Synovial biopsies in all cases showed a similar chronic inflammatory process, characterized by fibrin, collagen, and phagocytic cells. The intraarticular white cells were predominantly lymphocytes. Removal of the allograft resulted in resolution of the reaction in all of the patients. Three of the seven patients showed HLA conversion. Gas chromatography demonstrated detectable levels of ethylene chlorohydrin, a toxic reaction product of ethylene oxide, within the allograft and synovium 14 months following implantation of one graft. These seven cases presented strongly suggest a nonspecific or immune mediated response that must be further delineated. The use of freeze-dried, ethylene oxide-sterilized allografts using standard techniques cannot be recommended for reconstruction of the ACL.

One ACL in each of 11 mature goats was replaced with a freeze dried bone-ACL-bone allograft and a ligament augmentation device (LAD). The LAD was released from its tibial fixation at 3 months postoperation. Biomechanical, microvascular, and histological changes were evaluated 1 year following implantation. The reconstructed knees had a significantly greater total AP translation (3.1 +/- 0.5 mm) (mean and SEM) than the contralateral controls (1.0 +/- 0.1 mm). Differences in primary AP translation were responsible for 59% of the difference in total translation, with only a 0.6 mm difference in secondary translation. Neutral stiffness in the reconstructive knee was 22% of control, while stiffness at 30 N of anterior force was approximately 35% of controls. Ligament stiffness in the linear region for the ACL allograft/LAD was 53% of the control value of 691 N/mm. The maximum load of the allograft/LADs was 1,052 +/- 145 N, or 43% of the contralateral ACL control strength (2,448 +/- 144 N). Five of the six allografts failed at the femoral insertion. Energy (39%) to maximum load was less for allograft/LADs than controls but elongation to maximum load was the same as control. Histologic evaluation of the allograft/LADs revealed soft tissue cellular ingrowth into the LAD in the extraarticular portions. No bony growth into the LAD was observed. The collagen fibers of the graft appear to be arranged in a longitudinal orientation although some areas show chaotic collagen fibers. Microangiography revealed a periligamentous and endoligamentous vascular pattern reminiscent of a normal ACL and complete revascularization of the bone plugs.

Our understanding of the structure and function of the anterior cruciate ligament has progressed rapidly over the past decade. Arthroscope-assisted anterior cruciate ligament replacement is a new procedure that allows isometric placement of the anterior cruciate ligament graft. Postoperative rehabilitation is enhanced by preservation of the extensor mechanism.

There has been a growing interest in the use of allografts as ACL substitutes. Allografts are often freeze dried to increase shelf storage time and sterilized with ethylene oxide. This study was conducted to determine the effect of a specific ethylene oxide sterilization procedure and freeze drying process on the initial mechanical properties of femur-ACL-tibia preparations. Twelve knees (stifle joints) from six mature goats were divided into two groups (one knee of pair to each group). Knees were cleaned of all soft tissue except for the anterior cruciate, posterior cruciate, and collateral ligaments. Group 1 was sterilized with ethylene oxide (simulating clean procurement) then freeze dried. Group 2 was freeze dried only (simulating sterile procurement). The knees were rehydrated and then tested in tension to failure to determine their structural mechanical properties. The ethylene oxide-freeze dried specimens (Group 1) had a mean maximum load before failure of 2059 +/- 273 newtons (N) (+/- SE) which was not statistically different than the maximum load of the freeze dried specimens (Group 2) of 2023 +/- 214 N. The average strength of Group 1 and 2 combined was not significantly different than a third group of 12 normal femur-ACL-tibia controls which had an average maximum force of 2403 +/- 133 N. No significant differences between the groups were observed for stiffness, energy to maximum strength, or elongation to maximum force. It appears the freeze dry processing, with or without ethylene oxide sterilization, using the procedure we used, has, at most, a small effect on the initial mechanical properties of the preparations.(ABSTRACT TRUNCATED AT 250 WORDS)

One ACL in each of 11 mature goats was replaced with a freeze dried bone-ACL-bone allograft. One year following implantation the goats had their knees evaluated biomechanically and for microvascularity and histologic changes. The reconstructed knees had a significantly greater total AP laxity (3.8 +/- 0.6 mm) (mean and SEM) than the controls (1.0 +/- 0.1 mm). Differences in primary AP laxity were responsible for 81% of the difference in total laxity, with only a 0.4 mm difference in secondary laxity. Neutral stiffness in the reconstructive knee was 17% of control, while stiffness at 30 newtons (N) of anterior force was approximately 50% of controls. Ligament stiffness in the linear region for the ACL allograft was 35% of the control value of 686 N/mm. The maximum load of the allografts was 571 +/- 45 N, or 25% of the contralateral ACL control strength (2301 +/- 155 N). Five of the seven allografts failed at the femoral insertion. Both elongation (83%) and energy (21%) to maximum load were less for allografts than controls. Histologic evaluation of the allografts revealed the presence of a regular oriented dense connective tissue which resembled a normal ligament. Microangiography revealed a periligamentous and endoligamentous vascular pattern reminiscent of a normal ACL and complete revascularization of the bone plugs.

Magnetic resonance imaging (MRI) is an accepted non-invasive modality for evaluation of soft tissue pathology without exposure to ionizing radiation. Current applications demonstrate excellent visualization of the anatomy and pathology of various organs. Preliminary studies in the knee reveal fine resolution of anatomy and pathology involving the meniscus. The purpose of this study is to determine a prospective correlation between MRI scans and actual meniscal pathology as documented at the time of arthroscopy. MRI scans were obtained in 155 patients, on 156 knees (one patient with bilateral scans), with 86 patients (87 knees) eventually undergoing diagnostic and operative videoarthroscopy performed by the same surgeon (DWJ). All images were obtained on the same high-resolution 1.5 Tesla GE Signa Magnetic Resonance Scanner with the same radiologist performing all readings (PEB). The knees were studied in the coronal and sagittal plane using a spin echo sequence and 5 mm slice thicknesses. The menisci were described as having Grade 1, 2, or 3 changes, with Grade 3 reserved for complete tears. Using arthroscopy as the diagnostic standard, the accuracy of MRI in diagnosing medial and lateral meniscal tears was 93.1% and 96.6%, respectively with a Grade 3 MRI reading. For tears of the ACL, the accuracy was 96.6% as confirmed at arthroscopy. Five tears of the PCL were also documented by MRI and correlated with clinical evaluation. Other abnormalities seen were articular cartilage and osteochondral defects, bone tumors, tibial plateau fractures, Baker's cysts, and meniscal cysts. The MRI scan is a highly accurate, noninvasive modality for documentation of meniscal pathology as well as cruciate ligament tears in the knee.

Two patients who were dissatisfied with the functional results of knee fusion had conversion to total knee arthroplasty at one and 16 years following previously solid fusion. Both patients were over 65 years of age. Unconstrained prosthetic components were used and no special soft tissue stabilizing procedures were needed. At follow-up examinations, five and one-half and three years postoperatively, the results have been gratifying with good stability and adequate range of motion from 0 degrees to 90 degrees of flexion. Both patients were able to walk and climb stairs without support. The patients claimed that quality of function was significantly improved. Whenever possible, fusion of the knee in young people should be done so that this option remains open in later life. Arthrodesis is advised in young patients to allow for possibility of revision to total knee arthroplasty at a later date as technology improves.