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 621
Topic: Knee Sports
Figure 1 is the radiograph of a 50-year old woman with lateral-sided left knee pain. She noticed the pain over the last few months and has had no new injury. She had a microfracture performed of her lateral femoral condyle 5 years ago. What is the likely cause of the finding noted on her radiograph?
Correct Answer & Explanation
. Removal of the subchondral plate
Explanation
The radiograph reveals bony overgrowth of the microfracture site on the lateral femoral condyle. This occurs from violation of the subchondral plate during aggressive removal of the calcified cartilage layer during the microfracture. It is important during a microfracture to attempt to have a contained lesion and remove the calcified cartilage layer down to the subchondral plate, but avoid aggressively penetrating theplate.
Question 622
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. Risk for vascular injury during transtibial drilling for reconstruction of this injury is increased by
Correct Answer & Explanation
. greater knee 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 for vascular injury.
Question 623
Topic: Knee Sports
A 9-year-old girl, who is an avid soccer player, has intermittent spontaneous snapping in her left knee that has worsened. There is no reported trauma or prior surgeries to her knee. Despite working with her trainer, she has developed anterior-based knee pain and lacks full extension. Her knee skin is unremarkable, but there is fullness to palpation on the lateral aspect of her knee. Her range of motion demonstrates a lack of 15° of terminal extension and ligamentous examination is unremarkable. Considering possible surgical treatments for this patient, what is the most appropriate surgical treatment?
Correct Answer & Explanation
. Arthroscopic meniscal saucerization
Explanation
Surgical intervention of discoid meniscus is based on symptomatic patients. Complete discoid menisci are typically stable but are expected to have >4.5 times incidence of surgical intervention. Saucerization of symptomatic discoid meniscus is associated with better results with younger patients with increases of poor outcomes in adult-aged patients. Meniscal transplant may be an option, although long-term resultsare unknown.
Question 624
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. If the patient chooses surgical reconstruction, he should be advised that, when compared with a transtibial technique, the tibial inlay technique has been shown to provide
Correct Answer & Explanation
. more graft protection during cyclic loading.
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 beappropriate. 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 625
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. Left untreated, injury to this structure most likely will lead to degenerative changes in
Correct Answer & Explanation
. medial and lateral compartments.
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 abnormalDial 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 626
Topic: Knee Sports
A 16-year-old boy sustains a twisting injury to the left knee while wrestling. MRI scans are shown in Figures 22a through 22c. What is the most likely diagnosis? Review Topic
Correct Answer & Explanation
. Anterior cruciate ligament rupture
Explanation
The MRI scans show a displaced bucket-handle medial meniscus tear that can be visualized on coronal, sagittal, and axial views. The sagittal view shows the typical “double posterior cruciate ligament sign,” in which the low-signal bucket-handle fragment parallels the normal low-signal posterior cruciate ligament. The coronal and axial images both show the displaced medial meniscus in the notch.
Question 627
Topic: Knee Sports
What is the most reproducible landmark for the accurate anatomic placement of the tibial tunnel for an anterior cruciate ligament (ACL) reconstruction?
Correct Answer & Explanation
. Anterior border of the posterior cruciate ligament (PCL)
Explanation
The anterior border of the PCL is the most accurate and reproducible landmark for appropriate placement of the tibial tunnel for an ACL reconstruction. The central sagittal insertion point of the ACL is consistently 10 to 11 mm anterior to the anterior border of the PCL ligament. The anterior border of the tibia is not well visualized and does not serve as a reference point. While the posterior border of the anterior horn of the lateral meniscus could be used as a reference point, it has twice the variability of the PCL reference point. The posterior border of the tibia is difficult to identify and has greater variability than the PCL relative to the AP dimension of the proximal tibial surface. The anterior horn of the medial meniscus is also more variable than the PCL.
Question 628
Topic: Knee Sports
Figure 51 shows an arthroscopic view of the patellofemoral joint from an inferolateral portal. The arrow points to which of the following structures? Review Topic
Correct Answer & Explanation
. Loose body
Explanation
Synovial folds or plicae are the result of incomplete or partial resorption of the synovial membranes during fetal development of the knee. The arthroscopic view shows a medial patellar plica, which has been noted in 5% to 55% of all individuals but becomes symptomatic in only a small number of patients. Symptoms may include crepitus, pain, snapping, and swelling and often respond to nonsurgical management.
Question 629
Topic: Knee Sports
When compared with the normal anterior cruciate ligament (ACL), placement of an anterior cruciate ligament graft in the over-the-top position on the femoral side has what effect on its function?
Correct Answer & Explanation
. Lax in flexion and tight in extension
Explanation
The placement of an ACL graft with respect to its femoral and tibial attachments has a significant effect on its function. Evidence has shown that if the graft is placed in the over-the-top position, the graft will become lax in flexion and more taut with extension. Conversely, if the graft is placed too anterior on the femoral side, it will tighten in flexion and become lax in extension.
Question 630
Topic: Knee Sports
An 18-year-old man sustains a twisting injury to the left knee while playing football. An MRI scan is shown in Figure 48. What is the most likely diagnosis? Review Topic
Correct Answer & Explanation
. Anterior cruciate ligament rupture
Explanation
The MRI scan shows a displaced, bucket-handle lateral meniscus tear. The sagittal view shows the typical "large anterior horn" sign, or "double meniscus" sign in which the displaced bucket-handle fragment appears just anterior to the native anterior horn of the lateral meniscus. The presence of the fibula on the sagittal view confirms this as the lateral compartment. The image is lateral and the cruciate ligaments are not visualized. The articular cartilage shown does not demonstrate an osteochondral lesion.
Question 631
Topic: Knee Sports
What fibers of the anterior cruciate ligament tighten with extension of the knee? Review Topic
Correct Answer & Explanation
. Posterolateral
Explanation
The anterior cruciate ligament consists of two functional bundles: anteromedial and posterolateral. During extension of the knee, the posterolateral bundle becomes taut. In flexion, the anteromedial bundle is tight and the posterolateral bundle relaxes. Traditionally, anterior cruciate ligament reconstruction primarily recreates the anteromedial bundle. Recently, techniques for double bundle reconstruction have been described to recreate the normal anatomic relationship of the two bundles.
Question 632
Topic: Knee Sports
A 12.5-year-old boy reports intermittent knee pain and limping that interferes with his ability to participate in sports. He actively participates in football, basketball, and baseball. He denies any history of injury. Examination shows full range of motion without effusion. Radiographs reveal an osteochondritis dissecans (OCD) lesion on the lateral aspect of the medial femoral condyle. MRI scans are shown in Figures 14a and 14b. Initial treatment should consist of
Correct Answer & Explanation
. immobilization.
Explanation
This skeletally immature patient has a small OCD lesion that appears stable, and he has not undergone any treatment. Therefore, a trial of immobilization until pain resolves is the best initial choice. Thereafter, cessation of sport activities for 4 to 6 months may allow healing of the lesion. Surgical treatment of juvenile OCD lesions is reserved for unstable lesions, patients who have not shown radiographic evidence of healing and are still symptomatic after 6 months of nonsurgical management, or patients who are approaching skeletal maturity. Good results with stable in situ lesions that have failed to respond to nonsurgical management have been reported with both transarticular and retroarticular drilling. Results after excision alone are poor at 5-year follow-up, and it is unclear if microfracture will improve the long-term outcome. Mosaicplasty may be the next best option for patients who remain or become symptomatic after excision of the fragment and microfracture.
Question 633
Topic: Knee Sports
If a surgeon inadvertently burrs through the midlateral wall of C5 during a anterior corpectomy, what structure is at greatest risk for injury? Review Topic
Correct Answer & Explanation
. C5 root
Explanation
The vertebral artery is contained within the vertebral foramen and thus tethered alongside the vertebral body, making it vulnerable to injury if a drill penetrates the lateral wall. The C5 root passes over the C5 pedicle and is not in the vicinity. The C6 root passes under the C5 pedicle but is posterior to the vertebral artery and is only vulnerable at the very posterior-inferior corner. The carotid artery and the vagus nerve are both within the carotid sheath and well anterior.(SBQ12SP.54) Integrity of the posterior ligamentous complex (PLC) is a critical predictor of spinal fracture stability. Components of the PLC include the supraspinous ligament, interspinous ligament, ligamentum flavum and:Review TopicFacet joint capsulesFacet joint capsules, and facet jointsFacet joint capsules, facet joints, and the posterior longitudinal ligamentFacet joint capsules, and the posterior longitudinal ligamentPosterior longitudinal ligamentComponents of the PLC include the supraspinous ligament, interspinous ligament, ligamentum flavum and facet joint capsules.Numerous methods have been used to evaluate for PLC injury. Palpation is unreliable and has low accuracy. Radiographs can show characteristic flexion-distraction fracture patterns with widening or malaligment of the spinous processes. Computed tomography (CT) is more reliable than radiographs to provide indirect evidence of ligament injury. Magnetic resonance image (MRI) can provide direct evidence of soft-tissue injury, making it the preferred method in diagnosing ligamentous injury. However, MRI may not always be utilized due to situations involving emergency operations or contraindications to MRI, such as certain metal implants.Vaccaro et al. introduced a new classification system for thoracolumbar injuries, TLICS, based on morphological appearance, integrity of the posterior ligamentous complex, and neurological status. They advocate use of the system for nonoperative versus operative decision making and communication between surgeons.Varccaro et al. sought to determine the accuracy of magnetic resonance imaging (MRI) in diagnosing injury of the posterior ligamentous complex (PLC) in patients with thoracolumbar trauma. Forty-two patients with 62 levels of injury were studied. The sensitivity for the various PLC components ranged from 79% (left facet capsule) to 90% (interspinous ligament). The specificity ranged from 53% (thoracolumbar fascia) to 65% (ligamentum flavum). They concluded that the integrity of the PLC as determined by MRI should not be used in isolation to determine treatment.Incorrect Answers:
Question 634
Topic: Knee Sports
Figure 68 shows the MRI scan of a 13-year-old boy who has had knee pain and swelling following training lessons for ski racing for the past 6 months. The only abnormal finding on physical examination is an effusion. Management should consist of
Correct Answer & Explanation
. Cast immobilization for 6 weeks
Explanation
The lesion is osteochondritis dissecans. The primary determinant of treatment is an age of the patient at presentation. The presence of open physes classifies the lesion as the Juvenile form. It is theorized that, in both adult and juvenile forms, the articular cartilage softens as it loses the support of the subchondral layer of bone. If the disease process is not arrested, additional trauma causes separation of a bone fragment, and a crater remains. Most children who have juvenile osteochondritis dissecans and open physes can be successfully managed non-operatively. Cahill proposed limitation of activities until the patient was free of symptoms as well as protected weight bearing with use of splints or crutches. He recommended that nonoperative treatment be abandoned if symptoms persist for 3 months.
Question 635
Topic: Knee Sports
The patient returns 4 days after surgery and says he has noticed a red, swollen knee since yesterday. He reports a fever of 38.0°C since last evening and denies traumatic injury. He has an erythematous knee with a large, tense effusion; his range of motion is limited; and the surgical incisions are not draining. Radiographs taken in the office show no change from the immediate postsurgical images. Aspiration in the office returns 50 cc of cloudy, blood-tinged synovial fluid, and analysis of the fluid reveals a white blood cell count of 92000 (reference range 4500-11000 /µL). Which bacteria is most commonly responsible for this clinical scenario?
Correct Answer & Explanation
. Staphylococcus epidermidis
Explanation
Video 39 for referenceThis patient has a history of failed primary and revision ACL reconstructions, both times with medial meniscus repairs. The clinical scenario suggests a recurrent ACL injury with a recurrent medial meniscus tear that is now locked. The most critical risk factor for ACL reconstruction is age younger than 20 years. The meniscal repair success rate using an all-inside device is between 80% and 90%. Traditionally, it was believed that healing rates werehigher in ACL reconstruction, but current literature demonstrates a similar rate of healing associated with ACL reconstruction and no reconstruction of stable knees.The images show a vertical femoral tunnel resulting from this patient’s prior reconstruction and revision. The MR images reveal a locked bucket-handle tear of the medial meniscus, and the examination shows a positive Lachman test finding attributable to ACL graft failure. In the setting of a young individual who has failed 2 meniscal repairs, a third repair is not indicated. In addition to a revision ACL reconstruction to stabilize the knee, a partial medial meniscectomy is indicated. An attempt at revision medial meniscus repair would be indicated if the technique were poor in the first attempt, but a failed repair otherwise should indicate the need for partial meniscectomy. The postsurgical images reveal a much more anatomic position of the femoral tunnel that should provide better rotational control of the knee, thereby improving the pivot shift (compared to the vertical femoral tunnel).This patient has an obvious postsurgical infection based on the timing, examination, and results of the aspiration. In multiple studies of septic arthritis following ACL reconstruction, the most common pathogen was coagulase-negative staph (Staphylococcus epidermidis), followed by S. aureus. If S. aureus is the causative pathogen, the rate of necessary graft removal is higher because of the aggressive nature of this specific bacteria.
Question 636
Topic: Knee Sports
Injury to the popliteal artery during total knee arthroplasty (TKA) is most likely when placing a sharp retractor
Correct Answer & Explanation
. directly posterior to the posterior cruciate ligament (PCL).
Explanation
DISCUSSIONVascular 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 posterolateral to the PCL.
Question 637
Topic: Knee Sports
A patient has persistent instability symptoms one year after ACL reconstruction. Radiographs and MRI show an intact graft with a femoral tunnel that enters the notch at the 12 o'clock position. These clinical findings have been associated with which of the following? Review Topic
Correct Answer & Explanation
. Positive pivot shift and lower Lysholm scores
Explanation
The clinical presentation is consistent with a mal-positioned femoral tunnel leading to a vertical graft. Vertical grafts are associated with persistently positive pivot shift and lower Lysholm satisfaction scores. The Lysholm is a commonly used brief subjective questionnaire.Early arthroscopic single-incision transtibial ACL reconstruction often resulted in femoral tunnels which were at the top of the notch (12 o:clock position), rather than at the anatomic origin on the wall. The resulting vertical graft often improved anteroposterior laxity (as tested with the Lachman) but was less able to provide rotational stability (as tested with the Pivot shift).Lee et al. found a significant association between vertically positioned grafts and residual (postoperative) positive pivot shift tests. They also found patients with a vertically positioned graft had lower Lysholm satisfaction scores. They conclude more oblique positioning of the graft may have advantages in rotational stability, which in turn increase subjective patient satisfaction.Yasuda et al. noted that vertical non-anatomic tunnel placement cannot completely restore normal rotatory stability in laboratory studies.Incorrect
Question 638
Topic: Knee Sports
A 22-year-old collegiate baseball pitcher presents with posterior elbow pain during the deceleration phase of throwing. He lacks 15 degrees of full extension. Radiographs show posteromedial olecranon osteophytes. What is the primary underlying pathomechanical cause?
Correct Answer & Explanation
. Chronic attenuation of the anterior band of the medial ulnar collateral ligament
Explanation
Valgus extension overload syndrome is primarily caused by chronic insufficiency of the anterior band of the UCL. This permits excessive valgus opening during throwing, leading to reactive osteophyte formation and impingement in the posteromedial olecranon fossa.
Question 639
Topic: Knee Sports
A 25-year-old patent underwent anterior cruciate reconstruction (ACL) surgery 6 months ago. He returns to clinic with persistent instability. Physical examination reveals full range of motion of the knee. Additional tests show a 1A Lachman, 2+ pivot shift, negative external rotation dial, negative reverse pivot shift and negative McMurray. His radiographs are shown in Figure A. What is the likely cause of his persistent symptoms? Review Topic
Correct Answer & Explanation
. Missed posterolateral corner injury
Explanation
This patient has a vertical femoral tunnel position with rotatory instability. The most likely cause of his symptoms is a femoral tunnel placement that did not restore the posterolateral bundle.An anterior cruciate reconstruction (ACL) surgery with vertically placed grafts will result in persistent knee instability. Complaints will be mainly related to activities that require twisting or cutting movements. Physical examination will likely reveal a positive pivot shift exam due to the failure to reconstruct the posterolateral bundle of the ACL. Current standards for anatomic ACL reconstruction stress the importance of more horizontal graft placement (for example, 10:30 in a right knee vs 1:30 in the left knee). This allows for more rotational stability, while maintaining anterior stability. Improper femoral graft placement is one of the most common reasons for ACL revision surgery.Noyes et al. looked at patients undergoing revision ACL surgery with the use of patellar bone-tendon-bone (BTB) autograft. They showed the rate of graft failure to be three times higher than their reported failure rate after primary ACL reconstructions.Driscoll et al. performed a biomechanical study comparing 2 femoral tunnel locations in anatomic single-bundle anterior cruciate ligament reconstruction. They found that a femoral tunnel positioned in the anatomic center of the femoral origin of the ACL, as opposed to the anteromedial position, provides the greatest amount of rotatory and anterior stability.Figure A shows AP and lateral radiographs of the knee. Note there is a autograft ACL reconstruction with vertical placement of the femoral and tibial tunnel.Incorrect Answers:
Question 640
Topic: Knee Sports
A patient competing in a professional motocross race sustained a direct blow to the knee after falling off his bike at high speed. He sustained several lacerations as shown in Figure 60. He is able to actively extend his knee painlessly and his Lachman examination is negative. What is the most likely injury? Review Topic
Correct Answer & Explanation
. Anterior cruciate ligament tear
Explanation
It is important to recognize the injury pattern sustained by this motocross rider by inspection of his traumatic scars present anteriorly over the proximal tibia and the dorsum of the ankle and dorsum of the forefoot, indicating that his foot was in a plantar flexed position with a concomitant blow to the anterior tibia. This is a classic mechanism for a posterior cruciate ligament injury, and external clues (the scars) should not be overlooked when examining the knee. Occasionally, a posterior cruciate ligament injury is overlooked; however, putting together the patient's history, the examination (especially the posterior drawer and quadriceps active tests) provide a reliable diagnosis. Additional pathology should also be ruled out, such as a posterolateral corner injury and intra-articular pathology. Patella fracture, tibial tubercle avulsion, and patella tendon tears are unlikely because the patient can actively extend the knee. An anterior cruciate ligament tear is unlikely with a negative Lachman examination.
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