Magnetic resonance imaging (MRI) findings in anterior cruciate ligament (ACL) injury are well known, but most published reviews show obvious examples of associated injuries and give little focus to paediatric patients. Here, we demonstrate the spectrum of MRI appearances at common sites of associated injury in adolescents with ACL tears, emphasising age-specific issues.
Pictorial review using images from children with surgically confirmed ACL tears after athletic injury.
ACL injury usually occurs with axial rotation in the valgus near full extension. The MRI findings can be obvious and important to management (ACL rupture), subtle but clinically important (lateral meniscus posterior attachment avulsion), obvious and unimportant to management (femoral condyle impaction injury), or subtle and possibly important (medial meniscocapsular junction tear). Paediatric-specific issues of note include tibial spine avulsion, normal difficulty visualising a thin ACL and posterolateral corner structures, and differentiation between incompletely closed physis and impaction fracture.
ACL tear is only the most obvious sign of a complex injury involving multiple structures. Awareness of the spectrum of secondary findings illustrated here and the features distinguishing them from normal variation can aid in accurate assessment of ACL tears and related injuries, enabling effective treatment planning and assessment of prognosis.
• The ACL in children normally appears thin or attenuated, while thickening and oedema suggest tear.
• Displaced medial meniscal tears are significantly more common later post-injury than immediately.
• The meniscofemoral ligaments merge with the posterior lateral meniscus, complicating tear assessment.
• Tibial plateau impaction fractures can be difficult to distinguish from a partially closed physis.
• Axial MR sequences are more sensitive/specific than coronal for diagnosis of medial collateral ligament (MCL) injury.
Knee; Anterior cruciate ligament; Menisci; Adolescent; MRI
Injury to the anterior cruciate ligament (ACL) in the pediatric population is becoming more common, with the majority of ruptures occurring at the tibial insertion site. However, to our knowledge, there are no reports of avulsion in which the primary ACL insertion site is the anterior lateral meniscal root.
We report a rare case of a pediatric ACL/anterior horn of the lateral meniscus avulsion, which was successfully repaired arthroscopically.
In this patient, neither a mid-substance tear, nor a tibial eminence fracture was noted. Instead, the patient avulsed the tibial insertion of the ACL from its small footprint, which included an extensive attachment to the lateral meniscus.
We believe this developmental anomaly may provide further support of the shared embryological origin between the ACL and menisci. In this case report, we review the literature on anterior cruciate ligament injury and repair in the pediatric population.
ACL repair; meniscus repair; pediatric
Although tibial end avulsions of the anterior cruciate ligament are relatively common in clinical practice, avulsions of the femoral end of this ligament are by comparison rare. We present the case of an 11-year-old boy with a bony avulsion injury, which was presumed to have arisen from the tibial insertion of the anterior cruciate ligament but turned out instead to be an osteochondral avulsion fracture of the femoral origin. This unexpected finding that was not detected during preoperative workup resulted in the first attempt at surgical fixation being aborted. The need for a second planned definitive fixation procedure emphasises the importance of combining a thorough history and examination in association with appropriate imaging in the patient workup. The patient's definitive operative treatment and outcome are described. Although rare, surgeons (and emergency room doctors) treating such patients should include femoral end avulsion injuries of the anterior cruciate ligament in the differential diagnosis of a child presenting with an acute haemarthrosis of the knee. Furthermore, once diagnosed, early onward referral to an experienced knee surgeon is advocated.
Injury of the PCL of the knee in adults usually results in rupture rather than avulsion fracture and avulsions usually occur at the tibial insertion.
We report an avulsion of the PCL with a femoral origin in a 22-year-old man who was injured by hyperflexion of the knee and was treated with arthroscopy. There were two parts in the partial osteochondral avulsion fracture of the PCL posteromedial (PM) bundle. One part was fixed with polydioxanone suture through drill holes and the other was removed. The fracture healed after 3 months and the knee was stable. At 11 months postoperatively the patient had returned to full-time work without pain or restrictions. The Lysholm II knee score was 95 points. Physical examination showed a negative posterior drawer sign.
We identified four other reported cases of PCL femoral origin avulsion fractures in adults. The subjects were 20 to 25 years old in four of five reports, including our patient. Three of the five patients had involvement of only the lateral cortex of the medial femoral condyle whereas two other patients including our patient, had an osteochondral fracture. The mechanism of PCL avulsion seems to be similar to that of a PCL rupture.
Purposes and Clinical Relevance
The hyperflexion injury may result in injury of the PM bundle of the PCL. Our case and one other in the literature suggest such avulsions need not involve the entire PCL.
The authors report a case of acute knee injury in a 14-year-old teenager. The X-ray showed a so-called Segond’s fracture: a small avulsed bone fragment, elliptical in shape, lying immediately below the external tibial plateau, a few millimeters from the lateral tibial cortex. The fracture site was in the portion of the tibial condyle which is linked to the middle third of the lateral capsule by meniscal tibial fibers. Clinical examination under anesthesia and subsequent arthroscopy revealed a total intrasubstance ACL (anterior cruciate ligament) tear close to the proximal insertion. The authors confirm Segond’s report of a possible association of this avulsion fracture with ACL injuries, even in adolescence.
Segond fracture; ACL tear; Knee; Avulsion fracture
Tibial eminence avulsion fracture at the ACL footprint may be caused by high-energy forces such as a fall, in which the ACL ligament proves stronger than the forces that hold the bone together. For reasons of bone maturity however, tibial spine avulsion fractures where the ACL remains intact, typically occur in children but are rare in adults. This case demonstrates a rare type of adult tibial avulsion fracture with intact ACL and subsequent fragment fixation failure in which vitamin D deficiency may have been contributory. Because there is a high rate of inadequate vitamin D levels in patients undergoing orthopaedic surgery and a known impact on bone healing complications, post-operative bone fixation failure may also occur. This case report may therefore prompt further awareness for considering pre-surgical vitamin D deficiency screening in adults presenting with rare avulsion fractures, and may further demonstrate its impact on surgical outcomes.
Femoral avulsion fracture of the anterior cruciate ligament (ACL) in children and adolescents is rare, and its arthroscopic treatment is even more so. A femoral avulsion fracture of the ACL of a 14-year-old girl was arthroscopically reduced and fixed by a Kirschner wire (K-wire) via an inside-out technique. A 1.4-mm K-wire was drilled inside-out into the osseous defect of the lateral femoral condyle under arthroscopic visualization. The avulsed fragment was reduced and then drilled retrograde by the wire. After bending the intra-articular visible end of the K-wire by a knot pusher, the fragment was gently fixed by pulling the wire from outside. At 24 months, both knee stability and range of motion were the same in the operated and the healthy opposite leg. Magnetic resonance imaging evaluation and conventional radiographs showed an intact ACL without detectable disturbance in the growth plate. Only seven cases of a proximal avulsion of the ACL in children and adolescents have been published. Six were treated by open reduction and internal fixation, one by arthroscopic reduction without fixation.
Anterior cruciate ligament; Skeletally immature; Femoral avulsion fracture; Arthroscopic reduction and internal fixation
Post-traumatic osteoarthritis (PTOA) is a common long-term consequence of joint injuries such as anterior cruciate ligament (ACL) rupture. In this study we used a tibial compression overload mouse model to compare knee injury induced at low speed (1 mm/s), which creates an avulsion fracture, to injury induced at high speed (500 mm/s), which induces midsubstance tear of the ACL. Mice were sacrificed at 0 days, 10 days, 12 weeks, or 16 weeks post-injury, and joints were analyzed with micro-computed tomography, whole joint histology, and biomechanical laxity testing. Knee injury with both injury modes caused considerable trabecular bone loss by 10 days post-injury, with the Low Speed Injury group (avulsion) exhibiting a greater amount of bone loss than the High Speed Injury group (midsubstance tear). Immediately after injury, both injury modes resulted in greater than 2-fold increases in total AP joint laxity relative to control knees. By 12 and 16 weeks post-injury, total AP laxity was restored to uninjured control values, possibly due to knee stabilization via osteophyte formation. This model presents an opportunity to explore fundamental questions regarding the role of bone turnover in PTOA, and the findings of this study support a biomechanical mechanism of osteophyte formation following injury.
Mouse model; Post-traumatic osteoarthritis; ACL injury; Joint stability; Osteophyte
Posterior cruciate ligament (PCL) injuries are uncommon, and most occur in association with other lesions. The treatment of PCL injuries remains controversial; in addition, PCL injuries have been documented to have a propensity to heal. In the literature several different patterns of PCL injury have been described including midsubstance tears/injuries, tibial bony avulsions, femoral bony avulsions, and femoral “peel-off” injuries. A peel-off injury is a complete or incomplete soft-tissue disruption of the PCL at its femoral attachment site without associated bony avulsion. In recent years arthroscopic repair of femoral avulsion and peel-off lesions of the PCL has been reported. In most of these articles, a transosseous repair with sutures passed through 2 bone tunnels into the medial femoral condyle has been described. We present a case of a femoral PCL avulsion in a 20-year-old collegiate football player with an associated medial collateral ligament injury, and we report about a novel technique for PCL repair using 2 No. 2 FiberWire sutures and two 2.9-mm PushLock anchors (Arthrex) to secure tensioning the ligament at its footprint.
The most common fixation techniques for tibial avulsion fractures of the anterior cruciate ligament (ACL) described in the literature are screw and suture fixation. The fixation of these fractures with the TightRope® device might be an alternative. Up to now it has been commonly used in other injuries, such as acromioclavicular joint or syndesmosis ruptures. The purpose of this study was to evaluate the biomechanical properties of different fixation techniques for the reconstruction of tibial avulsion fractures.
Type III tibial avulsion fractures were simulated in 40 porcine knees. Each specimen was randomly assigned to one of four groups: (1) anterograde screw fixation, (2) suture fixation, (3) TightRope® fixation or (4) control group. The initial displacement, strength to failure and the failure mode were documented.
The maximum load to failure was 1,345 ± 155.5 N for the control group, 402.5 ± 117.6 N for the TightRope® group, 367 ± 115.8 N for the suture group and 311.7 ± 120.3 N for the screw group. The maximum load to failure of the control group was significantly larger compared to all other groups. The initial dislocation was 0.28 ± 0.09 mm for the control group, 0.55 ± 0.26 mm for the TightRope® group, 0.84 ± 0.15 mm for the screw group and 1.14 ± 0.9 mm for the suture group. The initial dislocation was significantly larger for the suture group compared to the TightRope® and control groups.
The TightRope® fixation shows significantly lower initial displacement compared to the suture group. The TightRope® fixation might be an alternative for the repair of ACL tibial avulsion fractures that can be used arthroscopically.
Tibial eminence fractures occur as a result of high amounts of tension placed upon the anterior cruciate ligament (ACL). The incidence of these fractures is higher among adolescent girls due to their inherent skeletal immaturity. In such an injury, direct trauma causes an avulsion fracture occurring at the tibial eminence while the ACL is spared. Imaging is used to confirm the diagnosis of a tibial eminence fracture and regardless of the extent of injury, rehabilitation is crucial for a full recovery. The following is a case study of a 17-year-old girl who was involved in a motor vehicle accident. In the accident, she sustained a left lateral tibial eminence fracture, along with soft tissue injuries at the cervical and lumbar spine. Her treatment included passive and active range of motion (ROM), strength training, physical modalities, and proprioceptive training of the injured areas. An improvement was noted post-treatment and after a 5-month follow-up according to subjective reports and objective assessments (ROM and girth measurements).
tibial eminence; fracture; rehabilitation; éminence du tibia; fracture; réadaptation
The anterior cruciate ligament (ACL) is a stabilizing structure to both anterior translation of the tibia with respect to the femur as well as rotation of the knee joint. Children and adolescents are susceptible to these injuries, and there are some who believe the incidence of ACL injuries in this population is increasing due to year round single sport participation. Pediatric ACL injuries are typically seen in several forms: tibial avulsion fractures, partial ACL tears, and full thickness ligament tears. There were and still are some who feel that ACL injuries should be treated non-operatively in the pediatric and adolescent population; however, recent literature refutes this notion. Several factors must be considered during pediatric and adolescent ACL reconstruction, each of which will be examined in this manuscript, including: status of the physis, reconstruction technique, and graft source.
Pediatric; Anterior cruciate ligament; ACL; Graft; Growth disturbance; Malalignment
The purpose of this technical note and accompanying video is to describe a modified arthroscopic suture fixation technique to treat tibial spine avulsion fractures. Twenty-one patients underwent arthroscopic treatment for tibial spine avulsion with our technique; they were clinically and biomechanically evaluated at 2 years' follow-up and showed optimal clinical and radiographic outcomes. Repair with this arthroscopic technique provides a significant advantage in the treatment of type III and IV fractures of the tibial eminence by obtaining arthroscopic fixation within the substance of the anterior cruciate ligament: suture methods based on the avulsed bone fragment are technically impossible, but sutures through the base of the ligament itself provide secure fixation, reducing the risks of comminution of the fracture fragment and eliminating the time for hardware removal. This arthroscopic technique restores the length and the integrity of the anterior cruciate ligament and provides a simplified, reproducible method of treating patients, including young patients, with low hardware costs in comparison to sutures using anchors or other hardware.
To the best of our knowledge there is no other report of an elderly patient who was surgically treated for a patellar fracture with tension band wiring and who subsequently suffered from an avulsion fracture of the tibial tuberosity. The combination of a patellar fracture and avulsion of the patellar ligament has only been described as complication after bone-patellar tendon-bone anterior cruciate ligament reconstructions. However, due to demographic changes and more elderly patients treated this injury may become more frequent in future.
We present the case of an 81 year old female who sustained an oblique patellar fracture after a direct contact injury of the left knee when falling on ice. Consequently the patellar fracture was openly reduced and stabilized with tension band wiring. The follow-up was uneventful till three months after surgery when the patient noticed a spontaneous avulsion fracture of the tibial tuberosity (Ogden type 3). The tibial tuberosity fragment was reattached with two non-resorbable sutures looped around two modified AO cortical 3.5 mm long neck screws. Intraoperatively multiple bone cysts were seen. Biopsies were not taken to prevent further fragmentation of the tibial tuberosity. The patient was followed up with anteroposterior and lateral full weight bearing radiographs and clinical assessment at 6, 12 weeks and 6 months after surgery. Recovery was completely pain free with full satisfaction.
In conclusion in elderly patients with a patella fracture a possible associated but not obvious fracture of the tibial tuberosity should be ruled out and the postoperative rehabilitation protocol after tension band wiring of the patella might have to be individually adjusted to bone quality and course of the fracture.
Numerous associated injuries (bony and/or soft tissue lesions) occur commonly in conjunction with fractures of the femoral shaft in young patients after high-energy injuries. Knee ligamentous injuries, historically called as the internal derangements of the knee or IDK, are mostly not visible in plain radiographs taken in the emergency and these injuries are likely to be overlooked by clinicians because first attention always goes to open wounds and radiologically visible injuries of the limb whenever a patient is received in a trauma unit.
Materials and Methods:
A total of 93 cases of lower limb long bone fractures were retrospectively analyzed from materials of a prospective study conducted on consecutive patients having high-velocity injuries to lower limb long bones with a view to confirm or rule out concomitant ipsilateral IDK in cases of femoral and tibial shaft fractures, that already employed a policy of focused clinical examination followed by arthroscopy of the ipsilateral knee, immediately after operative fracture fixation under the same anesthesia. The goal was to determine the incidence of concomitant internal derangement of the ipsilateral knee and to understand any value of adding arthroscopy to detect concomitant IDK in lower limb long bone fractures besides careful intraoperative examination to propose a recommendation thereof.
Concomitant knee injury was found in 14 femoral fractures and 1 tibial fracture. Fifteen out of 93 (16%) such cases had concomitant knee ligamentous or meniscal injures. A total of 13 anterior cruciate and 4 posterior cruciate tears, 11 collateral ligament tears, and 10 meniscal injuries were confirmed in these 15 knees. Femoral shaft fractures were associated with a high incidence of serious ligamentous, meniscal, and chondral injury. Twelve out of 41 femoral fractures had chondral injuries (contusion), especially of the patello-femoral articulation, identifiable during arthroscopy.
One should have high index of suspicion about internal knee injuries and capsule-ligamentous injuries while dealing with femoral shaft fractures in particular. Arthroscopy of knee may safely enhance the diagnosis of simultaneous IDK. We propose that when MR imaging is not possible and when contraindication for arthroscopy does not exist, a careful clinical examination followed by arthroscopy of the knee may be considered a useful adjunct in femoral shaft fractures as it can readily confirm IDK by its ability to objectively look, probe, and distinguish fragile tissue from a normal one. Further study in larger number of subjects is needed to validate our findings.
Arthroscopy; concomitant injury; chondral contusions; examination under anesthesia; femoral fractures; internal derangements of the knee; long bones
Lateral Patella dislocations are common injuries seen in the active and young adult populations. Our study focus was to evaluate medial patellofemoral ligament (MPFL) injury patterns and associated knee pathology using Magnetic Resonance Imaging studies.
MRI studies taken at one imaging site between January, 2007 to January, 2008 with the final diagnosis of patella dislocation were screened for this study. Of the 324 cases that were found, 195 patients with lateral patellar dislocation traumatic enough to cause bone bruises on the lateral femoral trochlea and the medial facet of the patella were selected for this study. The MRI images were reviewed by three independent observers for location and type of MPFL injury, osteochondral defects, loose bodies, MCL and meniscus tears. The data was analyzed as a single cohort and by gender.
This study consisted of 127 males and 68 females; mean age of 23 yrs. Tear of the MPFL at the patellar attachment occurred in 93/195 knees (47%), at the femoral attachment in 50/195 knees (26%), and at both the femoral and patella attachment sites in 26/195 knees (13%). Attenuation of the MPFL without rupture occurred in 26/195 knees (13%). Associated findings included loose bodies in 23/195 (13%), meniscus tears 41/195 (21%), patella avulsion/fracture in 14/195 (7%), medial collateral ligament sprains/tears in 37/195 (19%) and osteochondral lesions in 96/195 knees (49%). Statistical analysis showed females had significantly more associated meniscus tears than the males (27% vs. 17%, p = 0.04). Although not statistically significant, osteochondral lesions were seen more in male patients with acute patella dislocation (52% vs. 42%, p = 0.08).
Patients who present with lateral patella dislocation with the classic bone bruise pattern seen on MRI will likely rupture the MPFL at the patellar side. Females are more likely to have an associated meniscal tear than males; however, more males have underlying osteochondral lesions. Given the high percentage of associated pathology, we recommend a MRI of the knee in all patients who present with acute patella dislocation.
Anterior cruciate ligament (ACL) avulsion fracture is commonly associated with knee injuries and its management is controversial ranging from conservative treatment to arthroscopic fixation. The aim of our study was to assess the clinical and radiological results of arthroscopic staple fixation in the management of ACL avulsion fractures.
Materials and Methods:
Twenty-two patients (17 males and 5 females) who underwent arthroscopic staple fixation for displaced ACL avulsion fractures were analysed. The mean age was 32.2 years (15-55 years) with a mean followup of 21 months (6-36 months). All patients were assessed clinically by calculating their Lysholm and International Knee Documentation Committee (IKDC) scores and the radiological union was assessed in the followup radiographs.
The mean Lysholm score was 95.4(83-100) and the mean IKDC score was 91.1(77-100) at the final followup. In 20 patients anterior drawer's test was negative at the end of final followup while two patients had grade I laxity. Associated knee injuries were found in seven cases. The final outcome was not greatly influenced by the presence of associated injuries when treated simultaneously. At final followup all the patients were able to return to their pre-injury occupation
Arthroscopic staple fixation is a safe and reliable method for producing clinical and radiological outcome in displaced ACL avulsion fractures.
ACL avulsion; arthroscopy; staple
Bone bruise patterns are commonly seen after acute anterior cruciate ligament injuries; they represent a subchondral impaction injury that occurs in the lateral knee joint between the mid-lateral femoral condyle and the posterior lateral tibial plateau. These contusion patterns are present in the majority of noncontact ACL injuries. These injury patterns vary significantly in severity and this aspect is poorly understood. Edema patterns have gained increased interest in the literature of late; they may indicate the severity of the initial injury. They also may be correlated with the development of subsequent osteochondral defects and osteoarthritis. Given the location of this subchondral injury, it is plausible to assume that the geometry of the lateral femorotibial joint may play a role in ACL injury mechanism and severity of injury. We are reporting two cases of clinically identical ACL injuries. A patient with a flat lateral tibial plateau was noted to have a much larger bone edema pattern than a second patient with the highly convex lateral tibial plateau. This may shed light on the pathomechanics of ACL injury and suggests that an individual with a relatively flat tibial plateau has a stable lateral knee joint. Therefore, we hypothesize that much greater force is required to dislocate a flat and stable lateral femorotibial joint in a pivot shift pattern to produce an ACL injury. The greater force required results in a large bone edema pattern. Conversely, the individual with a relatively short and convex tibial plateau has an inherently unstable lateral joint and relatively smaller amounts of force would be needed to produce the identical injury to the ACL. As less force is required, smaller bone edema patterns result.
Recent years have seen ACL reconstruction performed in a broad range of patients, regardless of age, sex or occupation, thanks to great advances in surgical techniques, instrumentation and the basic research. Favorable results have been reported; however, we have not been able to locate any reports describing ACL reconstruction in patients with athetoid cerebral palsy.
We present herein a previously unreported anterior cruciate ligament (ACL) reconstruction performed in a patient with athetoid cerebral palsy. The patient was a 25-year-old woman with level II athetoid cerebral palsy according to the Gross Motor Function Classification System. She initially injured her right knee after falling off a bicycle. Two years later, she again experienced right-knee pain and a feeling of instability. A right-knee ACL tear and avulsion fracture was diagnosed upon physical examination and confirmed with magnetic resonance imaging (MRI) and X-ray examination at that time. An ACL reconstruction using an autologous hamstring double-bundle graft was performed for recurrent instability nine years after the initial injury. Cast immobilization was provided for 3 weeks following surgery and knee extension was restricted for 3 months with the functional ACL brace to prevent hyperextension due to involuntary movement. Partial weight-bearing was started 1 week postoperatively, with full weight-bearing after 4 weeks. The anterior drawer stress radiography showed a 63% anterior displacement of the involved tibia on the femur six months following the surgery, while the contralateral knee demonstrated a 60% anterior displacement of the tibia. The functional ACL functional brace was then removed. A second-look arthroscopy was performed 13 months after the ACL reconstruction, and both the anteromedial and posterolateral bundles were in excellent position as per Kondo’s criteria. The Lachman and pivot shift test performed under anesthesia were also negative. An anterior drawer stress radiography of the involved knee at 36 months following surgery showed a 61% anterior translation of the tibia. The preoperative symptoms of instability resolved and the patient expressed a high degree of satisfaction with the result of her surgery.
Athetoid cerebral palsy; Anterior cruciate ligament reconstruction; Involuntary movement; Stress radiography
The treatment of an anterior cruciate ligament (ACL) avulsion fracture is controversial, especially in skeletally immature patients, because of concerns about physeal damage. To reduce the risk of physeal injury, an arthroscopic technique was performed. A bioabsorbable suture anchor was inserted through anteromedial portals and fixed to a bioabsorbable suture anchor at the center of the fracture bed; it was then passed through the threads at the ACL avulsion fragment and tied with the ACL substance. After this, the avulsion fragment was repaired by an all-inside technique between the distal portion of the ACL and the transverse ligament and periosteum by a suture hook. The arthroscopic hybrid technique using a suture anchor with an all-inside repair is more rigid and safe. In addition, this physeal-sparing fixation is possible in immature patients.
The aims of this study were to evaluate the associated injuries occurring with acute perilunate instability and to assess the clinical and radiographic outcomes of perilunate dislocations and fracture–dislocations treated with a combined dorsal and volar approach.
A total of 45 patients (46 wrist injuries) with perilunate dislocations and fracture–dislocations were prospectively evaluated. The size of the mid-carpal ligament tear, the location of the scapholunate ligament tear, and the presence of osteochondral fragments and of the dorsal radiocarpal ligament avulsions were recorded at injury. Final clinical and radiographic outcomes were evaluated in 25 cases (25 wrists) with a minimum of 6 months of follow-up.
Intraoperative examination of the 46 cases with operative treatment showed the volar carpal ligament tear to be present 100 % of the time and to be an average length of 3.4 cm. Complete avulsion of the dorsal extrinsic radiocarpal ligaments was found in 65.2 % of cases. The scapholunate ligament was torn in 35 cases. Osteochondral fragments were found either volarly or dorsally in 74 % of the cases. The average flexion–extension arc was 82°, forearm rotation was 155°, and grip strength averaged 59 % of the uninjured hand. The average final scapholunate angle was 55° and the scapholunate gap was 2.2 mm.
Treatment of perilunate fracture–dislocations with a combined volar and dorsal approach results in reasonable and functional clinical results. The incidence of associated injuries with these carpal dislocations is high. Although the perilunate fracture–dislocations have a slightly better radiologic alignment than the dislocation group, the clinical outcome is similar.
Perilunate; Fracture; Dislocation; Osteochondral; Carpal ligament
Posterior cruciate ligament (PCL) insertion-site osteochondral avulsions in children, particularly from the tibia, are not commonly seen by orthopaedic surgeons. Because of the rarity of these injuries, careful attention to the specific physical examination and imaging findings seen with these injuries is necessary so that the proper diagnosis can be made. Osteochondral avulsions of the PCL can be missed on plain radiographs in skeletally immature patients, and therefore magnetic resonance imaging is necessary for proper diagnosis. With this knowledge, clinicians can formulate treatment plans which can return their patients to activities while avoiding potential morbidity resulting from missed diagnoses or improper treatment. We report two rare cases of PCL insufficiency stemming from tibial insertion osteochondral avulsions. Both patients underwent subsequent open reduction and internal fixation of the avulsion using two different fixation methods (bioabsorbable anchors versus cannulated screw and washer) and have returned to full sporting activities.
Electronic supplementary material
The online version of this article (doi:10.1007/s11999-008-0373-6) contains supplementary material, which is available to authorized users.
Bone bruises located on the lateral femoral condyle and posterolateral tibia are commonly associated with anterior cruciate ligament (ACL) injuries and may contribute to the high risk for knee osteoarthritis after ACL injury. The resultant footprint (location) of a bone bruise after ACL injury provides evidence of the inciting injury mechanism.
(1) To analyze tibial and femoral articular cartilage pressure distributions during normal landing and injury simulations, and (2) to evaluate ACL strains for conditions that lead to articular cartilage pressure distributions similar to bone bruise patterns associated with ACL injury. The hypothesis was that combined knee abduction and anterior tibial translation injury simulations would demonstrate peak articular cartilage pressure distributions in the lateral femoral condyle and posterolateral tibia. The corollary hypothesis was that combined knee abduction and anterior tibial translation injury conditions would result in the highest ACL strains.
Descriptive laboratory study.
Prospective biomechanical data from athletes who subsequently suffered ACL injuries after testing (n = 9) and uninjured teammates (n = 390) were used as baseline input data for finite element model comparisons.
Peak articular pressures that occurred on the posterolateral tibia and lateral femoral condyle were demonstrated for injury conditions that had a baseline knee abduction angle of 5°. Combined planar injury conditions of abduction/anterior tibial translation, anterior tibial translation/internal tibial rotation, or anterior tibial translation/external tibial rotation or isolated anterior tibial translation, external tibial rotation, or internal tibial rotation resulted in peak pressures in the posterolateral tibia and lateral femur. The highest ACL strains occurred during the combined abduction/anterior tibial translation condition in the group that had a baseline knee abduction angle of 5°.
The results of this study support a valgus collapse as the major ACL injury mechanism that results from tibial abduction rotations combined with anterior tibial translation or external or internal tibial rotations.
Reduction of large multiplanar knee motions that include abduction, anterior translation, and internal/external tibial motions may reduce the risk for ACL injuries and associated bone bruises. In particular, prevention of an abduction knee posture during initial contact of the foot with the ground may help prevent ACL injury.
bone bruise; ACL; articular cartilage; knee injury
Avulsion fractures of the posterior cruciate ligament (PCL) are uncommon. On the basis of the site of damage of the PCL, hyperflexion, pretibial trauma, and hyperextension are proposed as mechanisms of PCL injuries. On the other hand, avulsion fractures of the tibial condyle are also rare. We report a PCL-mediated avulsion fracture of the lateral tibial condyle along with the tibial insertion of the PCL by extension-distraction force on the knee that has not been previously described in any study. This rare case may imply that application of an extension-distraction force to the PCL cause the avulsion fracture.
The functional disability and high costs of treating anterior cruciate ligament (ACL) injuries have generated a great deal of interest in understanding the mechanism of noncontact ACL injuries. Secondary bone bruises have been reported in over 80% of partial and complete ACL ruptures.
The objectives of this study were (1) to quantify ACL strain under a range of physiologically relevant loading conditions and (2) to evaluate soft tissue and bony injury patterns associated with applied loading conditions thought to be responsible for many noncontact ACL injuries.
Controlled laboratory study.
Seventeen cadaveric legs (age, 45 ± 7 years; 9 female and 8 male) were tested utilizing a custom-designed drop stand to simulate landing. Specimens were randomly assigned between 2 loading groups that evaluated ACL strain under either knee abduction or internal tibial rotation moments. In each group, combinations of anterior tibial shear force, and knee abduction and internal tibial rotation moments under axial impact loading were applied sequentially until failure. Specimens were tested at 25° of flexion under simulated 1200-N quadriceps and 800-N hamstring loads. A differential variable reluctance transducer was used to calculate ACL strain across the anteromedial bundle. A general linear model was used to compare peak ACL strain at failure. Correlations between simulated knee injury patterns and loading conditions were evaluated by the χ2 test for independence.
Anterior cruciate ligament failure was generated in 15 of 17 specimens (88%). A clinically relevant distribution of failure patterns was observed including medial collateral ligament tears and damage to the menisci, cartilage, and subchondral bone. Only abduction significantly contributed to calculated peak ACL strain at failure (P = .002). While ACL disruption patterns were independent of the loading mechanism, tibial plateau injury patterns (locations) were significantly (P = .002) dependent on the applied loading conditions. Damage to the articular cartilage along with depression of the midlateral tibial plateau was primarily associated with knee abduction moments, while cartilage damage with depression of the posterolateral tibial plateau was primarily associated with internal tibial rotation moments.
The current findings demonstrate the relationship between the location of the tibial plateau injury and ACL injury mechanisms. The resultant injury locations were similar to the clinically observed bone bruises across the tibial plateau during a noncontact ACL injury. These findings indicate that abduction combined with other modes of loading (multiplanar loading) may act to produce ACL injuries.
A better understanding of ACL injury mechanisms and associated risk factors may improve current preventive, surgical, and rehabilitation strategies and limit the risk of ACL and secondary injuries, which may in turn minimize the future development of posttraumatic osteoarthritis of the knee.
anterior cruciate ligament; knee; injury mechanism; bone bruise