Effects of a novel medial meniscus implant on the knee compartments: imaging and biomechanical aspects.

The altered biomechanical function of the knee following partial meniscectomy results in ongoing articular cartilage overload, which may lead to progressive osteoarthritis (OA). An artificial medial meniscus implant (NUsurface® Meniscus Implant, Active Implants LLC., Memphis, TN, USA) was developed to mimic the native meniscus and may provide an effective long-term solution for OA patients, alleviate pain, and restore joint function. The goal of the current study was to investigate the potential effect of an artificial medial meniscus implant on the function of the lateral compartment of the knee and on the potential alterations in load distribution between the two compartments under static axial loading, using advanced piezo-resistive sensors. We used an integrated in situ/in vivo experimental approach combining contact pressure measurements of cadaveric knees with MRI joint space measurements of 72 mild OA patients. We employed this integrated approach to evaluate the mechanical consequences in both the medial (treated) and lateral knee compartments of two levels of meniscectomy and implantation of an artificial meniscus implant. Partial and subtotal meniscectomies of the medial meniscus resulted in statistically significant decrease in contact areas (p = 0.008 and p < 0.0001, respectively) and increased contact pressures in the medial compartment; however, implantation of the artificial meniscus implant restored the average contact pressure to 93 ± 14% of its pre-meniscectomy, intact value. Additionally, we found that neither the two different grades of medial meniscectomies, nor implantation of the artificial medial meniscus implant affected the lateral compartment of the knee. The MRI data from the patient cohort facilitated the integration of real-life clinical results together with the laboratory measurements from our cadaveric study, as these two approaches complement each other. We conclude that the use of the artificial medial meniscus implant may re-establish normal load distribution across the articulating surfaces of the medial compartment and not increase loading across the lateral knee compartment.

Opiates do not violate the viability and proliferative activity of human articular chondrocytes.

Articular cartilage injuries present a challenge for the clinician. Autologous chondrocyte implantation embedded in scaffolds are used to treat cartilage defects with favorable outcomes. Autologous serum is often used as a medium for chondrocyte cell culture during the proliferation phase of the process of such products. A previous report showed that opiate analgesics (fentanyl, alfentanil and diamorphine) in the sera have a significant inhibitory effect on chondrocyte proliferation. In order to determine if opiates in serum inhibit chondrocyte proliferation, twenty two patients who underwent knee arthroscopy and were anesthetized with either fentanyl or remifentanil were studied. Blood was drawn before and during opiate administration and up to 2 h after its discontinuation. The sera were used as medium for in vitro proliferation of both cryopreserved and freshly isolated chondrocytes, and the number and viability of cells were measured. There was no difference in the yield or cell viability between the serum samples of patients anesthetized with fentanyl when either fresh or cryopreserved human articular chondrocytes (hACs) were used. Some non-significant reduction in the yield of cells was observed in the serum samples of patients anesthetized with remifentanil when fresh hAC were used. We conclude that Fentanyl in human autologous serum does not inhibit in vitro hAC proliferation. Remifentanil may show minimal inhibitory effect on in vitro fresh hAC proliferation.

Assessment of cartilage repair after chondrocyte transplantation with a fibrin-hyaluronan matrix--correlation of morphological MRI, biochemical T2 mapping and clinical outcome.

OBJECTIVE: To evaluate change over time of clinical scores, morphological MRI of cartilage appearance and quantitative T2 values after implantation with BioCart™II, a second generation matrix-assisted implantation system. METHODS: Thirty-one patients were recruited 6-49 months post surgery for cartilage defect in the femoral condyle. Subjects underwent MRI (morphological and T2-mapping sequences) and completed the International Knee Documentation Committee (IKDC) questionnaire. MRI scans were scored using the MR Observation of Cartilage Repair Tissue (MOCART) system and cartilage T2-mapping values were registered. Analysis included correlation of IKDC scores, MOCART and T2 evaluation with each other, with implant age and with previous surgical intervention history. RESULTS: IKDC score significantly correlated with MOCART score (r = -0.39, p = 0.031), inversely correlated with previous interventions (r = -0.39, p = 0.034) and was significantly higher in patients with longer follow-up time (p = 0.0028). MOCART score was slight, but not significantly higher in patients with longer term implants (p = 0.199). T2 values were significantly lower in patients with longer duration implants (p < 0.001). This trend was repeated in patients with previous interventions, although to a lesser extent. CONCLUSIONS: Significant improvement with time from BioCart™II implantation can be expected by IKDC scoring and MRI T2-mapping values. Patients with previous knee operations can also benefit from this procedure.

Extensor mechanism reconstruction: a novel technique for bone patella allograft post partial patellectomy failure.

Extensor mechanism disruption, whether due to patella fracture or tendon rupture, generally occurs after low-energy trauma and frequently involves an indirect mechanism. When the fracture is comminuted and reconstruction is impossible, a partial or total patellectomy may be indicated. Although some authors advocate total patellectomy, partial patellectomy remains the standard treatment, especially for young and active patients. In the rare instance of a failed tendon repair after partial or total patellectomy, inadequate tissue is usually available for adequate restoration of the extensor mechanism. Extensor mechanism allograft, using the tibial tuberosity, patellar tendon, patella, and quadriceps tendon in continuity or the Achilles' tendon with calcaneal bone-block in continuity has been reported for extensor mechanism repair after total knee arthroplasty in patients who did not undergo patellectomy. We present a novel technique, using the bone patellar tendon bone allograft to reconstruct a posttraumatic defect of the extensor mechanism in a 28-year-old, active patient with a failed partial patellectomy following fracture of his patella. Union of the allograft was seen on x-ray after 4 months. After 6 months, the patient reached full range of motion and returned to his previous sporting activities.

[The treatment of focal chondral lesions of the knee].

Focal osteochondral lesions of the knee are a common cause of pain and other knee symptoms, and are mostly caused by traumatic injuries. The spontaneous repair ability of the articular cartilage tissue is very limited. Thus, focal chondral lesions result in early degenerative changes and post-traumatic osteoarthritis. The surgical treatment of focal osteochondral lesions can be divided into three major groups: cartilage debridement techniques, marrow stimulating techniques and transplantation techniques. Lesion debridement causes limited and temporary symptoms relief. While marrow stimulating techniques are considered simple, cheap and easy to perform, some of the transplantation techniques are complicated and consist of highly demanding surgery and new technologies of tissue engineering. Many published studies attempted to evaluate the efficacy of the treatment methods and to compare between them. There is no obvious or definite advantage of any one technique. There are relative advantages of some techniques according to the lesion size and patient's factors. Yet, among the current available treatment options none was found to produce hyaline cartilage consistently. In order to improve the current treatment and to find new treatment techniques, significant advances were achieved in the research of stem cells, scaffolds and growth factors in the last years. Further advances and more comparative and long term studies, particularly those that evaluate the efficacy of the new treatment techniques are needed.

Tailored tibial tubercle transfer for patellofemoral malalignment: analysis of clinical outcomes.

The purpose of this study was to describe the surgical technique, and evaluate and analyze the clinical outcomes of patients who underwent tibial tubercle realignment in our institution. Reported results of tibial tubercle transfer for patellofemoral malalignment vary considerably. Most authors rely mainly on the passive intraoperative patellar tracking test in determining the new location of the tibial tubercle. Conversely, the senior author relocates the tibial tubercle based on the intraoperative active and passive patellar tracking tests and the condition of the patellar articular surface. The medical records of 66 consecutive patients who underwent 80 tibial tubercle relocation procedures due to patellar instability or patellofemoral pain and maltracking were reviewed. Fifty-five patients with 69 operated knees participated in designated follow-ups which were conducted according to a predesigned protocol. The median follow-up was 6.2 years (range 2-13 years). Clinical outcomes significantly improved compared to the preoperative state; 72.5% of operated knees demonstrated good-to-excellent results according to the Lysholm and Karlsson scores, and physical findings supported the positive effect of the procedure. A statistically significant positive correlation was found between clinical outcomes and male gender, the absence of moderate to severe patellar chondral damage, and instability as the dominant preoperative symptom. Postoperative complication rate was low and patients with longer postoperative follow-ups demonstrated better clinical outcomes. The presented method of tibial tubercle transfer provided a good long-lasting surgical solution for patients with patellar instability and patients with patellar maltracking and anterior knee pain. Good prognostic factors included male gender, clinical patellar instability as the dominant preoperative symptom and intact patellar articular cartilage.

The importance of the valgus stress test in the diagnosis of posterolateral instability of the knee.

BACKGROUND: The diagnosis of posterolateral instability of the knee is often based on a typical indirect mechanism of injury, a history of "giving way" and a positive dial test. Our search of the English literature revealed no mention of including the valgus stress test in the diagnostic protocol for posterolateral instability. HYPOTHESIS: Based on our experience, we hypothesised that a medial collateral ligament (MCL) tear will also produce a positive dial test and that a valgus stress test would provide differential diagnostic information. METHODS: The MCL's of 14 fresh cadaveric knees (7 cadavers) were cut to simulate a grade 3 tear, taking care not to damage the medial retinaculum or the posteromedial stabilisers of the knee. The amount of tibial external rotation (the dial test) was measured for each knee before and after transection of the MCL. RESULTS: The results of the dial test after transection of the MCL were similar to those stemming from a solitary injury to the posterolateral corner. There was a significant increase in external rotation of the knee in 30 degrees and 90 degrees of flexion. More over, external rotation in 30 degrees was significantly greater than external rotation in 90 degrees of knee flexion. CONCLUSIONS: Whenever suspecting a posterolateral complex injury, one has to carefully perform a valgus stress test in 0 degrees and 30 degrees. Although the support of a clinical study is needed in order to make a definite conclusion, the dial test is probably not reliable in the presence of medial instability, and alternative diagnostic measures should be used.

[Anterior cruciate ligament injuries].

Anterior cruciate ligament (ACL) injuries are common, especially in young individuals who participate in sports activities associated with pivoting, decelerating and jumping. About 70% of ACL injuries do not result from direct contact. Establishing risk factors is important for prevention strategies. Risk factors for ACL injuries include environmental factors (e.g. high level of friction between shoes and the playing surface) and anatomical factors (e.g. narrow femoral intercondylar notch and increased joint laxity). History taking and physical examination provide the basis for diagnosis. Magnetic resonance imaging (MRI) is highly sensitive and specific and provides information about associated injuries such as meniscal tears. ACL-injury leads to knee instability which is associated with both acute dysfunction and long-term degenerative changes, such as osteoarthritis and meniscal damage. Surgical treatment of ACL-tears is effective in regard to short term rehabilitation but does not necessarily alter the natural course of this injury and its long-term complications. Therefore, surgical treatment should be reserved primarily for young individuals and for those who are high risk for ACL injury. ACL reconstruction is the standard surgery; however, a wide variety of reconstruction procedures is available and a gold standard procedure has not been defined. Nevertheless, arthroscopic reconstruction with either bone-patellar tendon-bone or a hamstring tendon graft is the most widely used method. Surgical timing is important. Early surgical intervention (i.e. within 4 weeks of injury) might increase complications.

Accuracy of magnetic resonance imaging of the knee and unjustified surgery.

Magnetic resonance imaging of the knee is greater than 90% accurate in detecting intraarticular disease when performed and interpreted by musculoskeletal magnetic resonance imaging specialists in specialized medical centers. However, independent imaging institutions often offer less expensive services to health insurers. We wondered if the magnetic resonance imaging performed in our community is of equivalent quality and accuracy. We studied a homogenous group of healthy, young, and fit military recruits to represent a cross section of our country's population. We analyzed all knee magnetic resonance images of soldiers who subsequently had primary arthroscopic knee surgery within a 3-month period from 1997-1998. The results were compared with surgical findings of four structures: medial meniscus, lateral meniscus, anterior cruciate ligament, and articular cartilage. Of the 1185 arthroscopies and 633 magnetic resonance images of the knee performed in 14 institutions, 139 paired magnetic resonance imaging arthroscopic reports met our inclusion criteria. The results showed a false positive rate of 65% for the medial meniscus, 43% for the lateral meniscus, 47.2% for the anterior cruciate ligament, and 41.7% for articular cartilage disease when compared with surgical findings. Accuracy rates were 52%, 82%, 80%, and 77%, respectively. Thirty-seven percent of the operations supported by a significant disorder on magnetic resonance imaging were unjustified. Our findings highlight the consequences that may occur when basing medical care on cost rather than quality of care.

[Sportsman's hernia--a plea for conservative therapeutical approach].

Sportsmen often suffer prolonged inguinal pain which can become a serious debilitating condition. In most cases the pain originates from a musculoskeletal problem. However, for some patients it has been suggested that the etiology is a weakness of the inguinal canal. This syndrome was termed "sportsman's hernia" although a hernia can not be found on physical examination. Imaging findings were found to be inconclusive regarding the alleged hidden hernia. Various types of operations, based on the variable theories regarding the pathophysiological process, have been developed for the treatment of this syndrome. Some surgeons focus on the external elements of the inguinal canal, and repair the external oblique fascia or enforce the groin with the rectus abdominis. Other surgeons perform an inguinal hernia repair procedure, either with sutures, synthetic mesh, or laparoscopically. Some researchers believe that the problem is in the lower abdominal muscles, or is caused by nerve entrapment, and treat it accordingly. There are no controlled comparative data on the results of the various surgical approaches, and there is no evidence that surgical treatment is more beneficial than conservative treatment. We recommend to operate only if conservative therapy, with prolonged rest, fails. During the operation the inguinal canal should be thoroughly explored, and will be enforced only if a hernia, or a definite weakness of the canal's floor, are found. Similarly, the release of a nerve should be performed only when the exploration reveals clear evidence of entrapment.

A miniature and mobile intermittent pneumatic compression device for the prevention of deep-vein thrombosis after joint replacement.

The WizAir-DVT is a miniature, lightweight (690 g), battery-operated and mobile intermittent pneumatic compression device (ICD), which enables continuous intraoperative use and immediate patient mobilization postoperatively. We compared its efficacy with a commonly used ICD, the Kendall SCD. Peak femoral vein flow velocity was measured in 20 apparently healthy volunteers at rest and with each device: we found no significant differences between them. A second prospective, randomized, clinical trial was used to compare the efficiency of the device in preventing deep venous thrombosis (DVT) after joint replacement in 50 patients (n=25/group). None developed DVT. Doppler ultrasonography revealed no significant differences. The WizAir-DVT antithrombotic compression device is as safe and effective as the Kendall SCD.

Endoscopic treatment of hindfoot pathology.

The arthroscope has served the orthopaedic surgeon as a diagnostic and operative tool since 1931. Several reports on its use in the treatment of extra-articular injuries have been published over the past few years. The surgical approach to the posterior ankle region is associated with some complications stemming from the poor blood supply to this region that can lead to wound complications and the formation of painful scars that later cause irritation when shoes are worn. We describe our experience in treating 3 hindfoot pathologic conditions, chronic Achilles tendonitis, os trigonum syndrome, and Haglund's deformity, by using an endoscope as an alternative to open surgical techniques. All the patients underwent a 2-portal endoscopic procedure, they suffered no complications, and they resumed their daily and sports activities after 2 to 3 months. Our results with the endoscopic treatment of hindfoot and Achilles tendon injuries indicate it to be a good alternative to the surgical approach, and to have the added advantage of reducing postoperative morbidity.

Recombinant human bone morphogenetic protein-2 for treatment of open tibial fractures: a prospective, controlled, randomized study of four hundred and fifty patients.

BACKGROUND: The treatment of open fractures of the tibial shaft is often complicated by delayed union and nonunion. The objective of this study was to evaluate the safety and efficacy of the use of recombinant human bone morphogenetic protein-2 (rhBMP-2; dibotermin alfa) to accelerate healing of open tibial shaft fractures and to reduce the need for secondary intervention. METHODS: In a prospective, randomized, controlled, single-blind study, 450 patients with an open tibial fracture were randomized to receive either the standard of care (intramedullary nail fixation and routine soft-tissue management [the control group]), the standard of care and an implant containing 0.75 mg/mL of rhBMP-2 (total dose of 6 mg), or the standard of care and an implant containing 1.50 mg/mL of rhBMP-2 (total dose of 12 mg). The rhBMP-2 implant (rhBMP-2 applied to an absorbable collagen sponge) was placed over the fracture at the time of definitive wound closure. Randomization was stratified by the severity of the open wound. The primary outcome measure was the proportion of patients requiring secondary intervention because of delayed union or nonunion within twelve months postoperatively. RESULTS: Four hundred and twenty-one (94%) of the patients were available for the twelve-month follow-up. The 1.50-mg/mL rhBMP-2 group had a 44% reduction in the risk of failure (i.e., secondary intervention because of delayed union; relative risk = 0.56; 95% confidence interval = 0.40 to 0.78; pairwise p = 0.0005), significantly fewer invasive interventions (e.g., bone-grafting and nail exchange; p = 0.0264), and significantly faster fracture-healing (p = 0.0022) than did the control patients. Significantly more patients treated with 1.50 mg/mL of rhBMP-2 had healing of the fracture at the postoperative visits from ten weeks through twelve months (p = 0.0008). Compared with the control patients, those treated with 1.50 mg/mL of rhBMP-2 also had significantly fewer hardware failures (p = 0.0174), fewer infections (in association with Gustilo-Anderson type-III injuries; p = 0.0219), and faster wound-healing (83% compared with 65% had wound-healing at six weeks; p =0.0010). CONCLUSIONS: The rhBMP-2 implant was safe and, when 1.50 mg/mL was used, significantly superior to the standard of care in reducing the frequency of secondary interventions and the overall invasiveness of the procedures, accelerating fracture and wound-healing, and reducing the infection rate in patients with an open fracture of the tibia.

Bone injury associated with anterior cruciate ligament and meniscal tears: assessment with bone single photon emission computed tomography.

RATIONALE AND OBJECTIVES: Acute injury of the menisci and ligaments about the knee joint is often associated with accompanying bone injury. The role of bone single photon emission computed tomography (SPECT) was assessed in this clinical setting. MATERIALS AND METHODS: Knee SPECT was performed in 94 patients with suspected ACL, meniscal tear, or both and was correlated with arthroscopy (n = 74), magnetic resonance imaging (MRI) (n = 37), or both. Scintigraphic findings were categorized based on their anatomic location and on uptake intensity (0-3 grade scale). RESULTS: Correlation with arthroscopy: Eleven patients had a normal arthroscopy of which in 10, SPECT images detected no abnormality. Sixty-three patients had abnormal arthroscopic findings, whereas all had abnormal SPECT studies. Thirty-eight patients had an anterior cruciate ligament (ACL) tear on arthroscopy. In this type of injury SPECT images detected increased uptake in the posterior aspect of the lateral tibial plateau (LTPp) with a positive predictive value (PPV) of 93% and a negative predictive value (NPV) of 97%. In 55% of the patients, increased uptake was also detected in the region of the middle sulcus of the lateral femoral condyle (LFCm): a "kissing" pattern. Tear of the medial meniscus was diagnosed by arthroscopy in 43 patients. SPECT images detected increased uptake in the medial tibial plateau (MTP) with a PPV of 78% and a NPV of 83%. Correlation with MRI: all seven cortical fractures seen on MRI were detected on SPECT. Twenty-eight patients had MRI findings suggestive of an ACL injury. Accompanying bone bruises were seen in 18 of them (64%). On SPECT images, all 28 patients with an ACL tear had increased uptake in the LTPp. Intensity of uptake in patients with associated bone bruise, however, was significantly higher; mean intensity grade 2.4 +/- 0.7 in case of accompanying bone bruise compared with 1.4 +/- 0.8 in case of an ACL tear without associated bone injury, P< 0.01. CONCLUSION: Results of the study suggest that bone SPECT is valuable in acute knee trauma for assessment of ACL, meniscal tears, or both and for detection of associated bone injury.

Avulsion of the triceps tendon during acceleration stress.

The authors present a rare case of triceps tendon avulsion associated with +5 G-force and muscle straining. Although failure of musculoskeletal system, mainly the cervical spine, secondary to high-G exposure has been reported, this is the first report they have found of a triceps tendon avulsion. Furthermore, unlike other traumatic triceps avulsions reported, the pilot involved had no known predisposing factors. Awareness of the possibility of such an injury must be maintained when a pilot of high performance aircraft presents with elbow pain.