Current trends in the anterior cruciate ligament part 1: biology and biomechanics.

A trend within the orthopedic community is rejection of the belief that "one size fits all." Freddie Fu, among others, strived to individualize the treatment of anterior cruciate ligament (ACL) injuries based on the patient's anatomy. Further, during the last two decades, greater emphasis has been placed on improving the outcomes of ACL reconstruction (ACL-R). Accordingly, anatomic tunnel placement is paramount in preventing graft impingement and restoring knee kinematics. Additionally, identification and management of concomitant knee injuries help to re-establish knee kinematics and prevent lower outcomes and registry studies continue to determine which graft yields the best outcomes. The utilization of registry studies has provided several large-scale epidemiologic studies that have bolstered outcomes data, such as avoiding allografts in pediatric populations and incorporating extra-articular stabilizing procedures in younger athletes to prevent re-rupture. In describing the anatomic and biomechanical understanding of the ACL and the resulting improvements in terms of surgical reconstruction, the purpose of this article is to illustrate how basic science advancements have directly led to improvements in clinical outcomes for ACL-injured patients.Level of evidenceV.

The posteromedial corner of the knee: an international expert consensus statement on diagnosis, classification, treatment, and rehabilitation.

PURPOSE: To establish recommendations for diagnosis, classification, treatment, and rehabilitation of posteromedial corner (PMC) knee injuries using a modified Delphi technique. METHODS: A list of statements concerning the diagnosis, classification, treatment and rehabilitation of PMC injuries was created by a working group of four individuals. Using a modified Delphi technique, a group of 35 surgeons with expertise in PMC injuries was surveyed, on three occasions, to establish consensus on the inclusion or exclusion of each statement. Experts were encouraged to propose further suggestions or modifications following each round. Pre-defined criteria were used to refine item lists after each survey. The final document included statements reaching consensus in round three. RESULTS: Thirty-five experts had a 100% response rate for all three rounds. A total of 53 items achieved over 75% consensus. The overall rate of consensus was 82.8%. Statements pertaining to PMC reconstruction and those regarding the treatment of combined cruciate and PMC injuries reached 100% consensus. Consensus was reached for 85.7% of the statements on anatomy of the PMC, 90% for those relating to diagnosis, 70% relating to classification, 64.3% relating to the treatment of isolated PMC injuries, and 83.3% relating to rehabilitation after PMC reconstruction. CONCLUSION: A modified Delphi technique was applied to generate an expert consensus statement concerning the diagnosis, classification, treatment, and rehabilitation practices for PMC injuries of the knee with high levels of expert agreement. Though the majority of statements pertaining to anatomy, diagnosis, and rehabilitation reached consensus, there remains inconsistency as to the optimal approach to treating isolated PMC injuries. Additionally, there is a need for improved PMC injury classification. LEVEL OF EVIDENCE: Level V.

Large variability exists in the management of posterolateral corner injuries in the global surgical community.

PURPOSE: The management of posterolateral corner (PLC) injuries has significantly evolved over the past 2 decades. The purpose of this study was to determine the current worldview of key concepts on the diagnosis, treatment strategy, and rehabilitation for patients presenting with PLC injuries. METHODS: A 12-question multiple-choice online survey was designed to address key questions in the diagnosis, treatment, and rehabilitation of PLC injuries. The survey was distributed to the most important international sports medicine societies worldwide. Clinical agreement was defined as > 80% of agreement in responses and general agreement was defined as > 60% of agreement in responses. RESULTS: 975 surgeons completed the survey with 49% from Europe, 21% from North America, 12% from Latin America, 12% from Asia, and smaller percentages from Africa and Oceania. Less than 14% of respondents manage more than ten PCL injuries yearly. Clinical agreement of > 80% was only evident in the use of MRI in the diagnosis of PLC injury. Responses for surgical treatment were split between isometric fibular-based reconstruction techniques and anatomically based fibular and tibial-based reconstructions. A general agreement of > 60% was present for the use of a post-operative brace in the early rehabilitation. CONCLUSION: In the global surgical community, there remains a significant variability in the diagnosis, treatment, and postoperative management of PLC injuries. The number of PLC injuries treated yearly by most surgeons remains low. As global clinical consensus for PLC remains elusive, societies will need to play an important role in the dissemination of evidence-based practices for PLC injuries. LEVEL OF EVIDENCE: IV.

Posterolateral corner of the knee: an expert consensus statement on diagnosis, classification, treatment, and rehabilitation.

PURPOSE: To develop a statement on the diagnosis, classification, treatment, and rehabilitation concepts of posterolateral corner (PLC) injuries of the knee using a modified Delphi technique. METHODS: A working group of three individuals generated a list of statements relating to the diagnosis, classification, treatment, and rehabilitation of PLC injuries to form the basis of an initial survey for rating by an international group of experts. The PLC expert group (composed of 27 experts throughout the world) was surveyed on three occasions to establish consensus on the inclusion/exclusion of each item. In addition to rating agreement, experts were invited to propose further items for inclusion or to suggest modifications of existing items at each round. Pre-defined criteria were used to refine item lists after each survey. Statements reaching consensus in round three were included within the final consensus document. RESULTS: Twenty-seven experts (100% response rate) completed three rounds of surveys. After three rounds, 29 items achieved consensus with over 75% agreement and less than 5% disagreement. Consensus was reached in 92% of the statements relating to diagnosis of PLC injuries, 100% relating to classification, 70% relating to treatment and in 88% of items relating to rehabilitation statements, with an overall consensus of 81%. CONCLUSIONS: This study has established a consensus statement relating to the diagnosis, classification, treatment, and rehabilitation of PLC injuries. Further research is needed to develop updated classification systems, and better understand the role of non-invasive and minimally invasive approaches along with standardized rehabilitation protocols. LEVEL OF EVIDENCE: Consensus of expert opinion, Level V.

Telomere length is independently associated with age, oxidative biomarkers, and sport training in skeletal muscle of healthy adult males.

In skeletal muscle, which mainly contains postmitotic myonuclei, it has been suggested that telomere length remains roughly constant throughout adult life, or shortens in response to physiopathological conditions in muscle diseases or in the elderly. However, telomere length results from both the replicative history of a specific tissue and the exposure to environmental, DNA damage-related factors, therefore the predictive biological significance of telomere measures should combine the analysis of the various interactive factors. In the present study, we analysed any relationship between telomere length [mean and minimum terminal restriction fragment (TRF) length] chronological age, oxidative damage (4-HNE, protein carbonyls), catalase activity, and heat shock proteins expression (αB-crystallin, Hsp27, Hsp90) in semitendinous muscle biopsies of 26 healthy adult males between 20 and 50 years of age, also exploring the influence of regular exercise participation. The multiple linear regression analysis identified age, 4-HNE, catalase, and training status as significant independent variables associated with telomere length and jointly accounting for ∼30-36% of interindividual variation in mean and/or minimum TRF length. No association has been identified between telomere length and protein carbonyl, αB-crystallin, Hsp27, and Hsp90, as well as between age and the variables related to stress response. Our results showed that skeletal muscle from healthy adults displays an age-dependent telomere attrition and that oxidised environment plays an age-independent contribution, partially influenced by exercise training.

Posterior cruciate ligament reconstruction using an arthroscopic femoral inlay technique.

Several techniques for posterior cruciate ligament reconstruction have been developed. The purpose of this paper is to present a new surgical technique that provides greater anatomical femoral fixation avoiding the sharp angle made by the graft at the exit of the femoral tunnel.

Release of growth factors after arthroscopic acromioplasty.

It has recently been postulated that a variety of growth factors may be released from cancellous bone after an acromioplasty. The aim of this study was to demonstrate the presence of growth factors in the subacromial space after acromioplasty. Between October 2006 and March 2007, 23 patients underwent arthroscopic acromioplasty. A sample of at least 3 ml of fluid from the shoulder was obtained 15 min after the end of the procedure. At the same time another sample of 3 ml of the patient's venous blood was obtained as a control. The concentrations of growth factors in the fluids collected were determined using enzyme-linked immunosorbent assay (ELISA). The growth factors assayed were platelet-derived growth factor-AB (PDGF-AB), basic fibroblast growth factor basic (bFGF) and transforming growth factor beta 1 (TGF-beta1). The concentrations of TGF-beta1 (p = 0.0001), PDGF-AB (p = 0.02), and bFGF (p < 0.0001) were significantly higher in the fluid from the subacromial space than in the blood sample. There are high concentrations of several growth factors in the subacromial space after acromioplasty.

Chondrolysis after partial lateral meniscectomy in athletes.

Rapid chondrolysis after partial arthroscopic lateral meniscectomy has been seldom reported in literature. Considering the relatively high number of partial lateral meniscectomy performed, we cannot understand why this complication is so rare. The purpose of this paper is to report a series of athletes developing a chondrolysis associated with posterolateral corner laxity after a partial lateral meniscectomy and attempt to hypothesize the pathogenesis of this devastating complication. Five male professional soccer players of Italian championship with a mean age of 26.8 years underwent a partial lateral meniscectomy because of a traumatic lateral meniscus tear. Patients showed a slight varus knee and there were clinical signs compatible with a meniscal tear. No other pathological sign were found. An MRI scan confirmed these findings. After surgery patients were unable to resume sport activities because of swelling and knee pain during training sessions. At a mean time of 8 months (range 6-12 months) from surgery patients were re-examined and a new MRI scan was performed. Clinical examination revealed a slight swelling of the knee and signs of posterolateral corner laxity. MRI scan revealed intra-articular fluid and pathological findings of knee posterolateral corner associated with a thinning of the articular cartilage. Arthroscopy showed free cartilagineous debris floating into the knee and a high grade of cartilage damage on the lateral compartment. The evaluation of lateral compartment, ruled-out a new tear of the meniscal remnant and showed a positive drive-trough sign with knee in the Fig. 4 positioning. All patients had an open re-tensioning of the posterior meniscofemoral capsule, and in one case, an augmentation of the popliteal tendon using a free semi-tendinous graft was also done. This surgery gave a complete resolution of symptoms and patients resumed sports activities without any restriction after a period between 4 and 5 months. Based on this experience we hypothesize that partial lateral meniscectomy may have a role in causing a subtle rotatory instability that combined with high stress of sports activity can dramatically increase the susceptibility of joint to chondrolysis, Varus knee seems to be a possible predisposing factor. Open surgery addressing the insufficiency of lateral or posterolateral corner has been found to be effective in improving knee function and resolve patients symptoms at a short-term follow-up.

Full arthroscopic inlay reconstruction of posterior cruciate ligament.

We report a full arthroscopic inlay reconstruction technique to avoid the morbidity of traditional open inlay procedure. With the transeptal approach a trough is created arthroscopically at the anatomical tibial insertion of the PCL, which must fit with the patellar bone block of a quadriceps tendon autograft. The bone plug is harvested with two nonabsorbable sutures, each end of which is passed through two holes from the cortical to the cancellous side. The graft is introduced into the knee joint from the posteromedial portal using two traction sutures passed previously through two transtibial tunnels exiting at the middle of the trough. Tibial graft fixation is achieved using the sutures knotted at the anterior aspect of the tibial cortex. Arthroscopic inlay procedure may be a rational surgical alternative because it reduces the crucial steps of an open inlay procedure, such as extensive exposure of the posterior capsule, the need of position change with risk of contamination, longer surgical time, and the risk of bone block fracture if an autograft is harvested. The arthroscopic procedure may also be performed also when hardware presence of previous surgery limits use of the open technique. We initially limited use of this technique to patients: (1) undergoing PCL revision surgery, (2) having hardware from previous tibial surgery, and (3) presenting a PCL lesion following posterior dislocation with previous vascular surgery. The results have been good, and we are now also using this technique for primary PCL reconstruction with favorable results.

Evaluation of posterior cruciate ligament healing: a study using magnetic resonance imaging and stress radiography.

PURPOSE: To review a series of tears of the posterior cruciate ligament (PCL) in order to understand its healing process, as well as to identify prognostic factors. TYPE OF STUDY: Prospective study. METHODS: Eighteen patients with isolated or combined PCL tears were evaluated and followed-up for 1 year after their initial injury. Magnetic resonance imaging (MRI) scans and stress radiographs were obtained serially at the time of injury, at 6 months, and at 12 months. RESULTS: Twelve of 18 PCL tears were found to have regained continuity at the 1-year follow-up. These patients complained of an isolated or combined PCL/medial collateral ligament injury at time 0 and all presented a posterior subluxation of less than 8 mm, detected with stress radiographs. The remaining 6 patients had posterior subluxations greater than 12 mm and presented with combined posterolateral corner injuries. CONCLUSIONS: This study underlines the importance of a complete MRI evaluation used in combination with stress radiography to adequately assess the healing process. The results obtained suggest that complete PCL tears with greater than 12 mm of posterior subluxation, as well as combined PLC injuries, are less likely to heal completely. These factors could further aid the surgeon in deciding the need and timing for surgical intervention in the acute setting of a PCL tear. LEVEL OF EVIDENCE: Level II.

Biomechanics of initial tibial fixation in posterior cruciate ligament reconstruction.

PURPOSE: Clinical success of posterior cruciate ligament (PCL) reconstruction continues to lag behind that of its anterior counterpart. The tibial site of PCL graft fixation has been a focus of recent research. This study examined the effect of combined distal and proximal tibial fixation on the ability of a transtibial PCL reconstruction to restore intact knee kinematics and in situ forces of the intact PCL. TYPE OF STUDY: Biomechanical study. METHODS: Ten human cadaveric knees were tested. A 134-N posterior tibial load was applied using a robotic/universal force moment sensor testing system at 0 degrees, 30 degrees, 60 degrees, 90 degrees, and 120 degrees of knee flexion. Each knee was tested under 4 conditions: intact, PCL-deficient, single-bundle transtibial reconstruction with distal tibial fixation, and single-bundle transtibial reconstruction with combined distal and proximal tibial fixation. Knee kinematics in 5 degrees of freedom for each condition were recorded and in situ forces of the intact PCL and the PCL grafts were determined. RESULTS: Reconstruction with combined fixation resulted in significantly less posterior tibial translation than reconstruction with distal fixation at 30 degrees, 90 degrees, and 120 degrees (P < .05), and restored intact knee kinematics at 90 degrees and 120 degrees (P > .05). Reconstruction with combined fixation more closely restored intact PCL in situ forces at 90 degrees (P < .05). CONCLUSIONS: Transtibial reconstruction with combined fixation more closely restores intact knee kinematics and in situ forces in the PCL at initial fixation than does reconstruction with distal tibial fixation. The improved kinematics and in situ forces seen with the combined fixation may be attributed to decreased functional graft length and increased stiffness of the PCL graft. CLINICAL RELEVANCE: Combined tibial fixation may provide a more stable reconstruction at initial fixation.

Arthroscopic diagnosis of the snapping popliteus tendon.

The syndrome of the snapping popliteus tendon is a rare cause of lateral knee pain and may be difficult to diagnose, leading to patients undergoing inappropriate therapy or surgical intervention. In this report, we describe the arthroscopic findings of the snapping popliteus tendon. Two men and 1 woman presented complaining of pain and a snapping sensation at the lateral aspect of the knee. No clear traumatic history was reported by any of the patients. Two patients had previously undergone partial lateral meniscectomy without relief of their symptoms. While the only consistently positive clinical sign was the Cabot sign, the arthroscopic findings confirmed the diagnosis in all cases. We observed in all cases inflammation around the tendon and visualized the portion of popliteus tendon near its insertion that is usually hidden by the femoral condyle. Further, flexion and extension with the limb in the tailor position revealed the snapping popliteus tendon. Successful treatment was achieved by securing the popliteus tendon to its sulcus on the lateral femoral condyle. Arthroscopic examination helps the surgeon to identify the snapping popliteus tendon to better treat this simple, yet oftentimes perplexing, condition.

Bone mineral density of the proximal metaphysis of tibia: clinical relevance in posterior cruciate ligament reconstruction.

The objective of this study was to evaluate the bone mineral density (BMD) of the proximal tibia in the area adjacent to the fixation of the posterior cruciate ligament (PCL) and compare with the BMD in a similar area at the ideal site for anterior cruciate ligament fixation. Twenty healthy male subjects, undertaking similar daily physical activity were enrolled for this study. The mean age of the subjects was 22 years (range 20-24 years). The bone mineral density (BMD) at the proximal tibia was calculated using a quantitative CT scan of the dominant knee, and the data were recorded in Hounsfield units (HU). Two circular regions of interest, anterior and posterior, of identical diameters (10 mm) and thicknesses (5 mm) were studied. The results showed a significantly higher BMD in the anterior region (162.4 +/- 33.8 HU) than in the posterior one (104 +/- 24.6 HU) with a statistically significant difference (p=0.0001). The clinical implication of this finding is that the fixation should provide a firm construct for PCL reconstructions and be specifically designed for working in low bone quality areas such as the posterior proximal tibia.

Biomechanical comparison of tibial inlay versus transtibial techniques for posterior cruciate ligament reconstruction: analysis of knee kinematics and graft in situ forces.

BACKGROUND: The tibial inlay technique for posterior cruciate ligament reconstruction has been proposed to provide a more anatomic reconstruction because it eliminates the sharp turn in the graft as it exits the proximal margin of the tibial tunnel in the transtibial technique. HYPOTHESIS: Reconstruction of the posterior cruciate ligament using the tibial inlay technique would more closely restore intact knee kinematics and in situ forces in the posterior cruciate ligament than would reconstruction using the transtibial technique. METHODS: Ten human cadaveric knees were tested in a controlled laboratory study. A robotic/universal force-moment sensor testing system was used to apply a 134-N posterior tibial load at 5 knee flexion angles: 0 masculine, 30 masculine, 60 masculine, 90 masculine, and 120 masculine. Four knee conditions were tested: intact, posterior cruciate ligament-deficient, and the single-bundle tibial inlay reconstruction and transtibial posterior cruciate ligament reconstruction. RESULTS: Both reconstruction techniques restored posterior tibial translations to 1.7 to 2.1 mm of the intact knee, with no statistical differences between the techniques. In response to the posterior tibial load, in situ forces in both grafts were between 7 and 39 N less than those in the intact posterior cruciate ligament, with no significant differences between the grafts. CLINICAL RELEVANCE: The study suggests that either technique may be performed with similar biomechanical results at initial fixation under these loading conditions.

Neurilemoma located at the patellar insertion of vastus medialis obliquus.

We report a case of a rare neurological tumour arising in the knee joint with no apparent connection to the major nerve trunks in the area. After the patient failed to improve through rehabilitation, surgery was performed, revealing a concomitant tear of the medial meniscus as well as a mass which was excised through an external supero-medial incision into the knee. Histopathological analysis later confirmed the diagnosis of a neurilemoma.

Surgical treatment of posterior cruciate ligament and posterolateral corner injuries. An anatomical, biomechanical and clinical review.

The posterior cruciate ligament has become an increasingly popular subject of orthopaedic research and debate. While biomechanical studies have shown its role as major stabilizer of the knee, clinical studies have shown its increasing incidence. Furthermore, injuries to posterolateral structures are frequently encountered and failure to recognize and treat this associated injury may lead to stretching or failure of the cruciate reconstruction. Surgical reconstruction of isolated/combined injuries is now more effective than before and different technical options are now available for the surgeon, even if much work remains ahead of us as we try to understand how to successfully treat these complex knee injuries.

Diagnostic evaluation of posterior cruciate ligament injuries.

The posterior cruciate ligament is one of the most controversial issues in sports medicine. There is no consensus in the literature with respect to its incidence, natural history, and treatment indications. Injury evaluation is often underestimated, with the result of misdiagnosed injury or wrong treatment. This contribution reviews the principles of diagnostic evaluation of posterior cruciate ligament injuries.

Stress radiography for quantifying posterior cruciate ligament deficiency.

PURPOSE: The objective of this study was to evaluate the efficacy of different stress radiography techniques in quantifying a posterior cruciate ligament (PCL) lesion. TYPE OF STUDY: Prospective serial study. METHODS: Sixty patients with subacute or chronic PCL injuries, confirmed using magnetic resonance imaging (MRI) or arthroscopic evaluation, were enrolled in this study. The patients underwent a KT-2000 (Medmetric, San Diego, CA) examination and a series of stress radiographs that included a radiographic posterior drawer test with Telos (Telos, Weterstadt, Germany) at 90 degrees and 25 degrees of knee flexion, an active radiograph at 90 degrees of knee flexion, and an axial view radiograph. RESULTS: Stress radiography performed with Telos showed an average posterior tibial displacement of 11.54 +/- 4.93 mm and 7.97 +/- 3.16 mm at 90 degrees and 25 degrees, respectively. The active radiographs showed an average posterior tibial displacement of 11.48 +/- 5.14 mm. CONCLUSIONS: Stress radiographs were shown to be superior to arthrometric evaluation in quantifying posterior tibial translation. The techniques performed with the knee at 90 degrees of knee flexion allowed for greater posterior tibial displacement and, consequently, an easier quantification of the degree of ligament insufficiency. Stress radiographs performed through hamstring contraction gave the same results as those performed with Telos at 90 degrees of knee flexion.

A modified bone-tendon-bone harvesting technique for avoiding tibial tunnel-graft mismatch in anterior cruciate ligament reconstruction.

Anatomic graft fixation in anterior cruciate ligament reconstruction has been shown to be extremely important for achieving acceptable postoperative knee stability. Different methods have been proposed for customizing graft length, so that anatomic graft fixation is obtained at the native anterior cruciate ligament site. A technique has been described for avoiding potential complications during the insertion of an interference screw at femoral tunnel and, ultimately, reducing the mismatch within the femoral tunnel. The aim of this article is to present a modified application to the tibial tunnel of a previously described technique for avoiding graft-tunnel mismatch. The advantages are related to the increase in graft complex stiffness, achievement of a more anatomic fixation, and the reduction in synovial fluid leakage.

Posterior cruciate ligament injuries in the athlete: an anatomical, biomechanical and clinical review.

Recently, the posterior cruciate ligament (PCL) has become an increasingly popular subject of orthopaedic research and debate. In the past several years, anatomic and biomechanical studies have provided invaluable information concerning the structure and function of the PCL. However, many aspects of PCL injury are still not fully understood. Diagnosis of the injury is often missed because of subtlety of symptoms and clinical findings, and current management strategies of PCL injury have experienced relatively poor clinical outcomes. Controversy exists concerning the most appropriate treatment, especially in cases of isolated PCL injury. The purpose of this review is to present a complete overview of the current knowledge regarding the basic science and clinical aspects of PCL injuries, with a specific focus on the athletic population.