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Knee Sports MCQs

Practice Set 27 of 102

This practice set contains high-yield board review questions covering key concepts in Knee Sports. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 521

Topic: Knee Sports

Figure 1 is the MRI scan of a patient with recurrent knee instability, which persists after a period of nonsurgical treatment. Anatomic reconstruction of the torn ligament is recommended. What radiographic finding is the most important independent predictor of recurrent instability following surgery?

. Tibial tubercle to trochlear groove (TT-TG) distance
. Patella alta
. Tibial slope
. Trochlear dysplasia

Correct Answer & Explanation

. Tibial tubercle to trochlear groove (TT-TG) distance

Explanation

The MR image is consistent with an episode of patellar instability with concomitant bruising of the medial patellar facet and lateral femoral condyle. The medial patellofemoral ligament appears torn and attenuated. Kita and associates reported that severe trochlear dysplasia is the most important predictor of residual patellofemoral instability after isolated medial patellofemoral ligament reconstruction. An increased TT-TG affected outcomes of patients with type D trochlear dysplasia (Dejour classification). Wagner and associates also found that high degrees of trochlear dysplasia correlate with poor clinical outcome due to graft overload in dysplastic situations. Other studies by Nelitz and associates and Matsushita and associates have also suggested that TT-TG distance did not reliably correlate with clinical outcome. Tibial slope would not affect recurrent patellar instability.

Question 522

Topic: Knee Sports

A 28-year-old man has left knee pain after a snow skiing accident. The MRI scan shown in Figure 47 reveals which of the following? Review Topic

. Osteosarcoma
. Bucket-handle medial meniscal tear
. Lateral collateral ligament tear
. Bone bruise
. Tibial spine avulsion

Correct Answer & Explanation

. Osteosarcoma

Explanation

Bone bruises are often noted on MRI after anterior cruciate and medial collateral ligament injuries. The significance of these injuries awaits long-term follow-up studies. The areas of increased signal on T2-weighted images represent areas of acute hemorrhage and are secondary to microfractures of the adjacent medullary trabeculae.

Question 523

Topic: Knee Sports

-What do the T2-weighted, fat-saturated MRI scans shown in Figures 76a through 76d reveal?

. Posterior cruciate ligament (PCL) tear, isolated
. PCL tear and medial meniscus tear
. Anterior cruciate ligament (ACL) tear, isolated
. ACL tear and medial meniscus tear

Correct Answer & Explanation

. Posterior cruciate ligament (PCL) tear, isolated

Explanation

DISCUSSION--The MRI scans show that edema is noted on the femoral insertion of the ACL consistent with a high-grade or complete ACL tear. The ACL is not visualized on the sagittal view, although the torn meniscus can be seen in the notch. On the coronal image, there is an empty lateral wall sign indicating proximal disruption of the ACL. The medial meniscus images show a disruption of normal meniscus morphology consistent with a bucket handle medial meniscus tear. Note the appearance on the sagittal MRI scan of what appears to be a second soft-tissue density in line with the PCL. This “double PCL” sign is highly indicative of a displaced medial meniscus tear rather than a displaced lateral meniscus tear.

Question 524

Topic: Knee Sports

An 18-year-old male soccer player sustains a knee injury during a game. Examination is notable for a positive pivot shift test. What other physical examination finding is most likely to be present? Review Topic

. Medial joint line tenderness
. Lateral joint line tenderness
. Positive dial test at 30° of knee flexion
. Varus laxity at 30° of knee flexion
. Positive posterior drawer test

Correct Answer & Explanation

. Medial joint line tenderness

Explanation

The patient has sustained a tear of his anterior cruciate ligament (ACL), as demonstrated by the positive pivot shift test; therefore, he would most likely exhibit lateral joint line tenderness indicative of a lateral meniscus tear, the most common intraarticular injury associated with an ACL tear.ACL tears usually occur as a result of a non-contact pivoting injury. Abnormal anterior translation results in bone contusions of mid-lateral femoral condyle and posterolateral tibia, which can be seen on MRI. Other concomitant intraarticular injuries include meniscal tears (lateral > medial), chondral damage and other ligamentous injury (MCL, LCL, PLC) usually found in cases of higher energy trauma such as a knee dislocation.Piasecki et al prospectively analyzed intraarticular injuries associated with ACL tears in high school athletes by gender and sport. There was no significant difference in mechanism of injury between sexes. Female basketball and soccer players had fewer intraarticular injuries (medial femoral condyle lesions, medial and lateral meniscus tears) compared to male athletes. The authors hypothesized that women may therefore enjoy a better prognosis following reconstruction.Spindler et al performed a prospective cohort study investigating concomitant intraarticular injuries in patients who underwent ACL reconstruction. Eighty percent of patients had a bone bruise on MRI, 68% involving the lateral condyle. At time of arthroscopic reconstruction, meniscal tears were identified in 56% of lateral menisci and 37% of medial menisci.Incorrect Responses:

Question 525

Topic: Knee Sports

A 24-year-old former high school wrestler had anterior cruciate ligament (ACL) reconstruction with hamstring autograft 6 years ago. He now experiences daily instability of his knee with routine activities including walking. Examination reveals a grade 3+ Lachman test with a soft endpoint, varus laxity at 30°, and a positive dial test at 30° that dissipates at 90° of knee flexion. He has mild medial joint line tenderness. When walking, there is a slight varus thrust. What treatment is most likely to lead to a successful outcome?

. Hamstring autograft
. Revision ACL reconstruction and posterior cruciate ligament (PCL) reconstruction
. Revision ACL reconstruction and posteromedial corner reconstruction
. Revision ACL reconstruction and posterolateral corner reconstruction

Correct Answer & Explanation

. Hamstring autograft

Explanation

This patient underwent an ACL reconstruction that has now failed. Based on his examination, he also has a posterolateral corner injury. Because this concomitant injury was not treated, the patient had undue strain on his graft, resulting in ultimate failure. Hamstring grafts are as effective as other graft types for ACL reconstruction. The medial meniscus provides secondary stabilization to the knee; however, this patient has a missed lateral ligamentous injury, and meniscus tears do not result in the development of a varus thrust. An unrecognized PCL tear likely results in mild-to-moderate medial and patellofemoral osteoarthritis without significant lateral laxity and thrust.

Question 526

Topic: Knee Sports

Figure 1 is the MR image of a 36-year-old athlete who is tackled from behind and falls forward onto his left knee. He has pain, swelling, and stiffness. Examination includes a moderate effusion, positive quadriceps active test, and normal Lachman test finding. The injured structure is composed of an

. anterolateral bundle that is tight in flexion and a posteromedial bundle that is tight in extension.
. anterolateral bundle that is tight in extension and a posteromedial bundle that is tight in flexion.
. anteromedial bundle that is tight in flexion and a posterolateral bundle that is tight in extension.
. anteromedial bundle that is tight in extension and a posterolateral bundle that is tight in flexion.

Correct Answer & Explanation

. anterolateral bundle that is tight in flexion and a posteromedial bundle that is tight in extension.

Explanation

The clinical description and MR image point to an injury to the posterior cruciate ligament (PCL). This ligament is thought to be primarily composed of anterolateral and posteromedial bundles, with the former tightening in flexion and the latter in extension. Because of alterations in knee kinematics and increased varus alignment in PCL insufficiency, contact stresses and cartilage loads increase in the patellofemoral and medial compartments. Although good outcomes may be obtained with transtibial, open inlay, and arthroscopic inlay techniques, one major difference is the creation of the “killer-turn” during the transtibial approach. This sharp turn in the graft as it emerges from the tibia appears to lead to more pronounced attenuation and thinning of the graft during cyclic loading. The scenario describes a patient with chronic PCL and posterolateral corner (PLC) injury, as evidenced by the varus thrust and abnormal Dial test finding. A valgus-producing osteotomy may be effective, and, in fact, may be the only treatment necessary to address chronic PLC injury. Accordingly, an opening lateral osteotomy would not be appropriate. Of the remaining responses, an osteotomy that increases tibial slope would also address the PCL deficiency by reducing posterior tibial sag. Vascular injury is an uncommon, but potentially devastating, complication associated with PCL surgery and may occur regardless of the technique used.Numerous strategies have been described to reduce the risk, including use of a posteromedial accessory incision to allow finger retraction of the popliteal neurovascular bundle, oscillating drills to prevent excessive soft-tissue entanglement, and tapered (rather than square) drill bits that may minimize cut-out of sharp edges as drilling reaches the posterior tibial cortex. Knee extension lessens, rather than increases, the distance between the posterior tibia and the neurovascular bundle and increases, not lessens, risk forvascular injury.

Question 527

Topic: Knee Sports
  • A 32-year-old man has swelling of the knee as a result of falling with the knee flexed and his foot in plantar flexion. A Lachman’s test reveals an apparent increase in anterior translation. Passive external tibial rotation at 30 degrees and 90 degrees is equal to the contralateral side, and the quadriceps active test is positive on the affected side. The neurovascular examination is normal. Treatment should consist of
. An anterior cruciate functional knee brace.
. A physical therapy program.
. Reconstruction of the posterior cruciate ligament and the posterolateral corner.
. Reconstruction of the posterior cruciate ligament.
. Reconstruction of the anterior cruciate ligament.

Correct Answer & Explanation

. An anterior cruciate functional knee brace.

Explanation

The question describes a patient with an isolated PCL injury. The mechanism of most athletic PCL injuries is a fall on the flexed knee with the foot in plantar flexion. The results of the physical examination—Lachman’s test with increased anterior translation and a positive quadriceps active test—suggests a PCL injury. The passive external tibial rotation at 30 degrees and 90 degrees being equal to the contralateral side suggest an intact posterolateral corner. In light of these findings, the patient appears to have an isolated PCL injury. In acute isolated posterior cruciate ligament tears with less than 10mm of posterior laxity at 90 degrees of flexion, current knowledge suggests nonoperative treatment that stresses aggressive quadriceps rehabilitation.

Question 528

Topic: Knee Sports

belowdepicttheAPandlateralradiographsobtainedfromayear-oldmanwithlong-standing
rightkneeosteoarthritisandpainthatisunresponsivetononsurgicaltreatment.Thepatientundergoes navigatedcruciate-retainingrighttotalkneearthroplasty.Aftersurgery,thispatientcontinuesto experiencepainandswellingofthekneewithrecurrenteffusions.Hereturnstotheofficereporting continuedpain2yearsaftersurgery.Hedescribesinstability,particularlywhendescendingstairs.On examination,rangeofmotionof0°to120°isobserved,withnoextensorlag.Slopeofthetibialcomponent is7°.Thekneeisstabletovarusandvalgusstressinextension,butflexioninstabilityispresentinboth theanterior-posteriordirectionandthevarus-valgusdirection.Bracingleadstoaslightdecreasein symptomsbutisnotwelltolerated.Isokinetictestingdemonstratesdecreasedkneeextensionvelocityat
midpush.Radiographsdemonstratewell-alignedandfixedkneeimplants.Aninfectionwork-upis negative.Whatisthemostappropriatesurgicalinterventionatthistime?

. Tibial polyethylene exchange
. Revision of the femoral and tibial components and conversion to a posterior stabilized insert
. Revision of the femoral and tibial components to a constrained rotating hinge prosthesis
. Isolated femoral component revision and upsizing of the femoral implant with a new posterior cruciate ligament (PCL)-retaining polyethylene insert

Correct Answer & Explanation

. Revision of the femoral and tibial components and conversion to a posterior stabilized insert

Explanation

DISCUSSION:The  patient’s  symptoms  at  follow-up—pain,  swelling,  and  difficulty  descending  stairs—suggest  knee flexion instability. Considering his history, an incompetent PCL must be considered. Revision of the knee to a posterior stabilized or nonlinked constrained condylar implant (depending on the condition of the ligaments) likely is needed to address his symptoms. The difference in extension stability and flexion stability makes polyethylene exchange a poor option. A constrained rotating hinge design is not necessary. Repeat use of a PCL-retaining insert is not recommended. Tibial and femoral revision both are required. Correction of excessive slope will be attained with tibial revision, femoral component revision is required to convert to a PCL-substituting design. There is also an opportunity to increase posterior condylar offset if needed.

Question 529

Topic: Knee Sports

What is the effect on knee kinematics following placement of an anterior cruciate ligament (ACL) graft at the 12 o’clock position? Review Topic

. Decreased rotational stability
. Decreased anterior-posterior stability
. Decreased flexion
. Decreased extension
. Graft failure secondary to impingement

Correct Answer & Explanation

. Decreased rotational stability

Explanation

Endoscopic ACL reconstructive techniques may result in a vertical graft placement. The reconstructed ligament will resist anterior translation of the tibia but the graft will not restore rotatory stability. Decreased flexion and extension are caused by placement of the femoral tunnel too anterior and posterior, respectively. Impingement of the graft on the femoral notch is caused by anterior placement of the tibial tunnel or inadequate notchplasty.

Question 530

Topic: Knee Sports

A 16-year-old boy falls while playing soccer. He reports that his knee buckled when he planted his leg to kick a ball. He noticed an obvious deformity of his knee, which spontaneously resolved with a “clunk.” He could not finish the game but was able to bear weight with a limp. He has had two similar episodes but has never sought medical attention. An initial examination demonstrated an effusion, tenderness at the proximal medial collateral region and medial patellofemoral retinaculum, decreased range of motion, and patella apprehension. A lateral patellar glide performed at 30° of flexion was 3+. He was otherwise ligamentously stable, and there were no other noteworthy findings.Figures 3 and 4 are this patient's proton density fat-saturated MR images. His tibial tubercle-trochlear groove (TT-TG) distance is 12 mm, and he has normal limb-alignment film findings. Treatment at this stage should include

. hinged knee bracing, protected weight bearing, and physical therapy.
. anteromedialization of the tibial tubercle.
. internal fixation and medial patellofemoral ligament (MPFL) reconstruction.
. arthroscopic lateral retinacular release.

Correct Answer & Explanation

. internal fixation and medial patellofemoral ligament (MPFL) reconstruction.

Explanation

This patient’s examination and history indicate recurrent patellar dislocations. Radiographs show an osseous or osteochondral loose fragment. There is no evidence of an obvious nondisplaced fracture or physeal changes. In the setting of suspected patella dislocation or subluxation with loose fragment seen on radiograph, an MRI is indicated. Lateral release alone is seldom indicated in a knee that is normal before injury. The examination and MRI do not indicate a need for medial collateral ligament repair.Treatment should consist of arthroscopy or arthrotomy and attempted internal fixation of this fragment. If fixation is not possible, the loose body can be removed. Normal TT-TG values, an increased lateral patellar glide, and a history of recurrent patellar dislocations after trauma suggest MPFL incompetenceand the need for reconstruction.

Question 531

Topic: Knee Sports

During right knee anterior cruciate ligament (ACL) reconstruction, after drilling an appropriately positioned and referenced tibial tunnel, the surgeon finds that the transtibial guide is placing the femoral tunnel at 11:30 within the intercondylar notch. Which of the following choices will best enable appropriate graft placement in this clinical scenario? Review Topic

. Revise the tibial tunnel to be more oblique.
. Revise the tibial tunnel to be more posterior.
. Convert to a transtibial double-bundle ACL.
. Prepare the femoral tunnel via an anteromedial portal or two-incision technique.
. Hyperflex the knee and place the femoral tunnel with the transtibial guide.

Correct Answer & Explanation

. Revise the tibial tunnel to be more oblique.

Explanation

Anatomic placement of the femoral tunnel is best achieved in this clinical scenario by drilling the femoral tunnel through the anteromedial portal or via a two-incision technique. Several recent studies have demonstrated the difficulty that may be encountered in restoring true ACL anatomy on the femoral side when placing a femoral tunnel through a transtibial technique. While this is not always the case and this technique may be reasonable and sufficient, it is important for orthopaedic surgeons to critically assess tunnel placement intraoperatively and postoperatively tominimize errant tunnel placement, demonstrated in the literature as the most common cause of ACL failure and need for revision. In this not uncommon clinical scenario, simply converting to a two-incision ACL technique or drilling through the anteromedial portal with the knee hyperflexed will permit accurate femoral tunnel placement and increase the likelihood of an optimal clinical outcome. Femoral tunnel accuracy with these techniques is enhanced by a lower starting point in the intercondylar notch. Familiarity with these techniques is valuable for surgeons performing ACL reconstruction. Revising the tibial tunnel in this scenario would likely lead to bone compromise of the proximal tibia and may interfere with graft fixation and incorporation. Converting to a double-bundle ACL with a transtibial technique would not correct the vertical femoral tunnel. Hyperflexion of the knee may improve femoral tunnel placement to some extent, but is unlikely to allow anatomic placement of a femoral tunnel when the transtibial guide lies in a clearly excessive vertical position.

Question 532

Topic: Knee Sports

Risk for vascular injury during transtibial drilling for reconstruction of this injury is increased by

. accessory incisions.
. use of tapered drill bits.
. use of oscillating drills.
. greater knee extension.

Correct Answer & Explanation

. accessory incisions.

Explanation

DISCUSSIONThe clinical description and MR image point to an injury to the posterior cruciate ligament (PCL). This ligament is thought to be primarily composed of anterolateral and posteromedial bundles, with the former tightening in flexion and the latter in extension. Because of alterations in knee kinematics and increased varus alignment in PCL insufficiency, contact stresses and cartilage loads increase in the patellofemoral and medial compartments. Although good outcomes may be obtained with transtibial, open inlay, and arthroscopic inlay techniques, 1 major difference is the creation of the “killer-turn” during the transtibial approach. This sharp turn in the graft as it emerges from the tibia appears to lead to more pronounced attenuation and thinning of the graft during cyclic loading.In Question 12, the scenario describes a patient with chronic PCL and posterolateral corner (PLC) injury, as evidenced by the varus thrust and abnormal Dial test finding. A valgus-producing osteotomy may be effective, and, in fact, may be the only treatment necessary to address chronic PLC injury. Accordingly, an opening lateral osteotomy would not be appropriate. Of the remaining responses, an osteotomy that increases tibial slope would also address the PCL deficiency by reducing posterior tibial sag.Vascular injury is an uncommon, but potentially devastating, complication associated with PCL surgery and may occur regardless of the technique used. Numerous strategies have been described to reduce the risk, including use of a posteromedial accessory incision to allow finger retraction of the popliteal neurovascular bundle, oscillating drills to prevent excessive soft-tissue entanglement, and tapered (rather than square) drill bits that may minimize cut-out of sharp edges as drilling reaches the posterior tibial cortex. Knee extension lessens, rather than increases, the distance between the posterior tibia and the neurovascular bundle and increases, not lessens, risk for vascular injury.

Question 533

Topic: Knee Sports

An 18-year-old woman injures her left knee playing soccer. At the time of anterior cruciate ligament (ACL) reconstruction, she was noted to have an irreparable posterior horn medial meniscus tear. Partial meniscectomy will have what primary effect? Review Topic

. Increase medial femoral-tibial peak contact loads
. Increase medial compartment contact area
. Decrease in situ forces in the ACL graft
. Decrease anterior tibial translation
. Increase posterior tibial translation

Correct Answer & Explanation

. Increase medial femoral-tibial peak contact loads

Explanation

The medial meniscus distributes force through the medial compartment. Peak loads in the affected compartment are increased by partial and complete meniscectomy. The posterior horn of the medial meniscus is also an important secondary restraint to anterior tibial translation in the ACL-deficient knee. In situ forces in the reconstructed ACL are increased with loss of the posterior horn of the medial meniscus.

Question 534

Topic: Knee Sports

Figures 2a and 2b are this patient’s proton density fat-saturated MR images. His tibial tubercle-trochlear groove (TT-TG) distance is 12 mm, and he has normal limb-alignment film findings. Treatment at this stage should include

. hinged knee bracing, protected weight bearing, and physical therapy.
. anteromedialization of the tibial tubercle.
. internal fixation and medial patellofemoral ligament (MPFL) reconstruction.
. arthroscopic lateral retinacular release.

Correct Answer & Explanation

. internal fixation and medial patellofemoral ligament (MPFL) reconstruction.

Explanation

DISCUSSIONThis patient’s examination and history indicate recurrent patellar dislocations. Radiographs show an osseous or osteochondral loose fragment. There is no evidence of an obvious nondisplaced fracture or physeal changes. In the setting of suspected patella dislocation or subluxation with loose fragment seen on radiograph, an MRI is indicated. Lateral release alone is seldom indicated in a knee that is normal before injury. The examination and MRI do not indicate a need for medial collateral ligament repair. Treatment should consist of arthroscopy or arthrotomy and attempted internal fixation of this fragment. If fixation is not possible, the loose body can be removed. Normal TT-TG values, an increased lateral patellar glide, and a history of recurrent patellar dislocations after trauma suggest MPFL incompetence and the need for reconstruction.

Question 535

Topic: Knee Sports
Figures below show the radiographs and the MRIs obtained from a 32-year-old man with worsening left knee pain. A 3-foot hip-to-ankle radiograph shows a 13-degree varus knee deformity. The patient sustained a major left knee injury 5 years ago and a confirmed complete anterior cruciate ligament (ACL) tear. He managed this injury nonsurgically with a functional brace but experienced worsening pain. He was seen by an orthopaedic surgeon 18 months ago, and a medial meniscus tear was diagnosed; the tear was treated with an arthroscopic partial medial meniscectomy. Since then, his knee has been giving way more often, and he no longer feels safe working on a pitched roof. The patient received 6 months of formal physical therapy and was fitted for a new functional ACL brace, but he still has pain and instability. He believes he has exhausted his nonsurgical options and would like to undergo surgery. What is the most appropriate treatment at this time?
. ACL reconstruction and subsequent proximal tibial osteotomy
. ACL reconstruction alone
. Distal femoral osteotomy with simultaneous ACL reconstruction
. Proximal tibial osteotomy with subsequent ACL reconstruction

Correct Answer & Explanation

. Proximal tibial osteotomy with subsequent ACL reconstruction

Explanation

DISCUSSION: Proximal tibial osteotomy is the most appropriate intervention to correct varus malalignment and to reduce stress on the ACL. In some cases, proximal tibial osteotomy alone may address both pain and instability, but if instability persists, particularly in the setting in which instability can be dangerous, subsequent ACL reconstruction can further stabilize the knee with less stress on the graft after the correction of malalignment. Varus alignment places increased stress on the native or reconstructed ACL. ACL reconstruction should be performed only at the same time as or following proximal tibial osteotomy to correct alignment in the setting of varus malalignment. It is not appropriate to perform ACL reconstruction prior to proximal tibial osteotomy in this setting. Distal femoral osteotomy is not indicated to correct varus malalignment. Varus alignment places increased stress on the native or reconstructed ACL, and ACL reconstruction alone is not indicated for this patient.

Question 536

Topic: Knee Sports

Figure 35 is the MR image of an 18-year-old man who has had knee pain with running for 5 months. What is the most appropriate treatment?

. Arthroscopic or open reduction and internal fixation with possible bone grafting
. Arthroscopic chondroplasty
. No weight-bearing activity for 6 weeks and then re-evaluate
. Retrograde subchondral drilling without fixation

Correct Answer & Explanation

. Arthroscopic or open reduction and internal fixation with possible bone grafting

Explanation

DISCUSSIONThe MR image shows an osteochondritis dissecans (OCD), which is an acquired lesion of the subchondral bone. Patients with OCD initially report nonspecific pain and variable amounts of swelling. Initial radiographs help to identify the lesion and establish the physes status. MRI is useful for assessing potential for the lesion to heal with nonsurgical treatment. This lesion is unstable, considering the fluid line between the OCD and the underlying normal bone. Nonsurgical treatment is appropriate for small, stable lesions in patients with open physes and focuses on activity restriction for 3 to 9 months. Surgical treatment is necessary to address unstable or detached lesions. Stable lesions with intact articular cartilage can be treated with subchondral drilling to stimulate vascular ingrowth, with radiographic healing at an average of 4.4 months. Fixation is indicated for unstable or hinged lesions, and stabilization of the fragment can be achieved using a variety of implants through an arthroscopic or open approach. The fragment should be salvaged and the normal articular surface restored whenever possible.

Question 537

Topic: Knee Sports
Injury to the popliteal artery during total knee arthroplasty (TKA) is most likely to occur when placing a sharp retractor
. directly posterior to the posterior cruciate ligament (PCL).
. posteromedial to the PCL.
. posterolateral to the PCL.
. in the posteromedial corner of the knee.

Correct Answer & Explanation

. posterolateral to the PCL.

Explanation

DISCUSSION: Vascular complications during TKA are rare but do occur. Traditionally, it was taught that the popliteal artery was situated posterior to the PCL; however, more recent anatomic dissections have demonstrated that this artery is usually located posterolateral to the PCL.

Question 538

Topic: Knee Sports

A collegiate division I football player ruptures his anterior cruciate ligament (ACL). After counseling him, you agree to perform a double-bundle ACL reconstruction. Which of the following is a correct statement for this technique? Review Topic

. The anteromedial (AM) bundle limits translation and the posterolateral (PL) bundle controls rotation.
. The PL bundle limits translation and the AM bundle controls rotation.
. The anterolateral (AL) bundle limits translation and the posteromedial (PM) bundle controls rotation.
. Both the AL and the PM control rotation equally.
. The AL bundle controls rotation and the PM bundle limits translation.

Correct Answer & Explanation

. The anteromedial (AM) bundle limits translation and the posterolateral (PL) bundle controls rotation.

Explanation

The ACL is composed of two anatomic bundles: the anteromedial (AM) and the posterolateral (PL). They are both considered important to the stability of the knee. Although they work in concert, the AM bundle controls translation, especially in flexion, whereas the PL bundle prevents rotation.

Question 539

Topic: Knee Sports
A 15-year-old boy reports feeling a pop and notes sudden giving way of the left knee while playing basketball. He has immediate pain and swelling in the knee. An AP radiograph is shown in Figure 32. A small avulsion fragment from the lateral tibial margin is the only finding. What is the most likely diagnosis?
. Avulsion of the lateral collateral ligament
. Avulsion of the pes anserinus
. Avulsion of the iliotibial band
. Tear of the anterior cruciate ligament
. Tear of the posterior cruciate ligament

Correct Answer & Explanation

. Tear of the anterior cruciate ligament

Explanation

An avulsion fracture from the lateral tibial margin carries the eponym Segond fracture and is pathognomonic for an anterior cruciate ligament (ACL) tear. The fragment is located posterior to Gerdy’s tubercle and is superior and anterior to the fibular head. It represents an avulsion of the lateral capsular ligament of the knee and is caused by the same mechanism that causes the ACL tear. The pes anserinus is the insertion point of the medial hamstrings and would not be affected in a lateral avulsion injury. The posterior cruciate ligament may be seen on a lateral view if associated with an avulsion fragment, but a tear of the PCL generally cannot be diagnosed on an AP view. The insertion of the iliotibial band is broad and is unlikely to produce an avulsion injury such as that seen in the radiograph. This view is not consistent with the appearance of a lateral collateral ligament injury.

Question 540

Topic: Knee Sports

What do the T2-weighted, fat-saturated MRI scans shown in Figures 1 through 4 reveal?

. Posterior cruciate ligament (PCL) tear, isolated
. PCL tear and medial meniscus tear
. Anterior cruciate ligament (ACL) tear, isolated
. ACL tear and medial meniscus tear

Correct Answer & Explanation

. ACL tear and medial meniscus tear

Explanation

The MRI scans show that edema is noted on the femoral insertion of the ACL consistent with a high-grade or complete ACL tear. The ACL is not visualized on the sagittal view, although the torn meniscus can be seen in the notch. On the coronal image, there is an empty lateral wall sign indicating proximaldisruption of the ACL. The medial meniscus images show a disruption of normal meniscus morphology consistent with a bucket handle medial meniscus tear. Note the appearance on the sagittal MRI scan of what appears to be a second soft-tissue density in line with the PCL. This "double PCL" sign is highlyindicative of a displaced medial meniscus tear rather than a displaced lateral meniscus tear.

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