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PubMed1978

Demonstration of rotatory instability in injured knees by stress radiography.

Rotatory instability of injured knees may be demonstrated by stress radiography by recording the different movements of the medial and lateral tibial condyle at pull or push with the knee in 90 degrees flexion. The displacements of the condyles are expressed in millimetres, not degrees. Comparison with the healthy knee is always used. The displacement of a tibial condyle has to exceed 3.0 mm in relation to the healthy knee to be defined as pathological. If the movements of both condyles exceed the movements in the healthy knee by more than 3.0 mm in the same direction a drawer sign is present--if only one of them moves, an abnormal rotation is present. When a drawer sign is present there may still be a greater displacement of one of the tibial condyles which means a rotatory instability added to the drawer sign, designated a complex rotatory instability. All types of rotatory instabilities, simple and complex, are defined and discussed, in relation to the classification of Nicholas, Trickey and Slocum & Larson. Forty-one cases of abnormal rotation were demonstrated in this series by stress radiography. The direction of rotation and the type of instability are described and compared with the operative findings. The findings are in agreement with those of the above-mentioned authors and the experimental work of Warren et al.

Humans↗
PubMed1989

Patellar subluxation. A recent history.

For 15 years (1955 to 1970), I was plowing "new ground" pretty much by myself. When you plow behind an old mule and hit a stump hole full of cottonmouth moccasins, you have to get on the move in a hurry and figure out some solution to the predicament or you won't get your corn planted. So, I was not treating the overweight, knock-kneed, loose-jointed, teenaged girl, but the young boy or girl who thought that he or she was an athlete and had dreams of being a star. If rehabilitation did not work, then I thought a lateral release, an Elmslie, and nothing short of a full reconstruction would solve the problem. One had to develop as much vastus medialis obliquus power as this dysplastic muscle could generate, had to transfer the strong vastus lateralis to a more central pull, and, with the distal reconstruction, correct any patella alta and Q-angle abnormality. One had to give the knee every possible advantage in order to serve an athlete. As Hippocrates so wisely noted, one needed to study the athlete to know, with appropriate modifications, what is best for every patient, young or old. In the late 1960s and early 1970s, many fine young orthopedists were stimulated by the information of the AAOS postgraduate courses in sports medicine. They, after having gained further through their own experiences, have become the major contributors to our increasing knowledge of the patellofemoral joint, especially in athletes, and many of these fine "young" (now a little older) orthopedists are now the contributors to this issue. They are giving you their experiences, knowledge, and lessons. A close and repeated study of their information must be combined with compassion for your patient. Then, only experience will develop the desired fine tuning.

Humans↗
PubMed1979

The arthroscope in the diagnosis of disorders of the patellofemoral joint.

Despite our current knowledge and accumulated information, orthopedic surgeons often experience difficulties in the diagnosis of internal derangement of the knee. Too often, the admission diagnosis I.D.K. means "I don't know." Disorders of the patellofemoral joint contribute to this difficulty and may simulate torn menisci and loose bodies, as well as the instability which results from rotary displacement. Patients often have difficulty describing and locating their symptoms, and 2 or more pathologic lesions may be present in the same joint. Early lesions involving the articular cartilage are especially difficult to diagnose. Even the most astute clinician cannot rely entirely on his clinical judgement, and, at times, needs the assistance of other diagnostic measures. Arthroscopy is an invaluable aid in the diagnosis of all intra-articular pathology, permitting the proper incision in the proper area, often eliminating the necessity of opening the joint and always avoiding unnecessary meniscectomy.

Adult↗
PubMed1994

Effects of patella alta and patella infera on patellofemoral contact forces.

The relationship between patella alta and patellar subluxation may, in part, reflect the relationship between the height of the patella above the tibiofemoral joint line and the patellofemoral contact force. This study reports on the direct in vitro measurement of the patellofemoral contact force, and its point of application on the patella, as a function of patellar height. The contact force was measured by a specially designed six-degree-of-freedom force transducer under loading simulating rising from a chair. The magnitude of the resultant contact force increased significantly with superior displacement of the patella. The magnitude of the resultant contact force changed as much as 3% per millimeter of change in patellar height. The details of this response varied among the knees tested and depended on the original anatomical patellar height. For a high-riding patella, the onset of tendofemoral contact is delayed and the magnitude of the patellofemoral contact continues to increase with increasing flexion angle. Early onset of tendofemoral contact associated with a low-riding patella results in a concomitant reduction in the magnitude of the contact force. The medially directed component of the contact force acting on the patella resists lateral subluxation of the patella. This force component increased with superior displacement of the patella. This may explain in part the tendency for a high-riding patella to sublux. For all seven specimens tested the point of application of the resultant contact force migrated superiorly with inferior displacement of the patella.

Aged↗
PubMed1978

The abnormal lateral patellofemoral angle: a diagnostic roentgenographic sign of recurrent patellar subluxation.

On roentgenograms made with the patient supine, the knees flexed 20 to 30 degrees, the x-ray tube between the ankles, and the cassette held proximal to the knees and perpendicular to the x-ray beam, it was found that a line between the femoral condyles and a line between the margins of the lateral facet of the patella formed the lateral patellofemoral angle, an angle that was of diagnostic value in patients with subluxation of the patella. In 100 clinically normal patients, these lines were parallel in three and formed an angle open laterally in ninety-seven. In thirty patients with subluxation of the patella, the lines were parallel in twenty-four and formed an angle open medially in six. In 100 patients with chondromalacia of the patella, however, the roentgenographic study was of no diagnostic value since the lines were parallel in ten and formed an angle open laterally in ninety.

Female↗
PubMed1981

[On the cause of the anterolateral instability of the knee joint. A study on 20 cadaver knee joints with special regard to the tractus iliotibialis (author's transl)].

Experiments on 20 cadaver knee joints are reported on. A short medial incision was made to transect the anterior cruciate ligament. Through a long lateral incision the lateral structures (lateral capsule, lateral collateral ligament, and iliotibial tract) were transected in variable series to check their influence on the pivot shift-sign. The results are tabulated. The anterior cruciate ligament is shown to be the key structure for the pivot shift-sign. This sign is only markedly positive when the lateral structures are intact. Depending on the pattern of transection of the lateral structures the pivot shift-sign is less marked or totally absent. It is also shown why this sign is missing in the unhappy triad. Because the intact distal part of the iliotibial tract is responsible for the pivot shift-sign, a detailed description of its anatomy and physiology is given.

Fascia Lata↗
PubMedDate not supplied

An analysis of the pivot shift phenomenon. The knee motions and subluxations induced by different examiners.

The description of the pivot shift test and its modifications is for the most part based on clinical observations. We wished to precisely determine the knee motions and medial-lateral tibiofemoral compartment subluxations that examiners induce in the knee joint to produce the pivot shift phenomenon. Eleven skilled knee surgeons performed the pivot shift test on an instrumented cadaveric lower limb. The anterior cruciate and superficial medial collateral ligaments (long fibers) of one limb were sectioned to produce an abnormal state. An instrumented spatial linkage allowed all six degrees of freedom motions to be measured. Before and after ligament sectioning we determined the limits of knee motion under defined loading conditions. The tibial and femoral bony landmarks were digitized to determine the positions of the medial and lateral tibial plateaus in reference to the femoral condyles during the pivot shift tests. Each examiner performed his pivot shift test. The analysis of the data showed that examiners typically induced a coupled anterior translation and internal tibial rotation to produce an anterior tibial subluxation, and a coupled posterior translation and external tibial rotation to induce the reduction event. The magnitude of anterior subluxation of each plateau depended upon the examiner's technique. The maximal anterior subluxation of the lateral tibial plateau varied from 14 to 19.8 mm (mean, 17.2 +/- 2.0 mm), whereas anterior subluxation of the medial tibial plateau ranged from 6 to 16.9 mm (mean, 11.2 +/- 3.3 mm).(ABSTRACT TRUNCATED AT 250 WORDS)

Femur↗
PubMed1997

Arthroscopy for chronic hemophilic synovitis of the knee.

Between 1988 and 1995, 32 knee joints (29 patients) with hemophilic arthropathy underwent arthroscopy. The spectrum of procedures ranged from resection of fibrous plicae to synovectomy. Technical difficulties appeared in cases of scarred fixed patella, pronounced posterior tibia subluxation, and severe fibrous ankylosis. All operations done between 1988 and 1991 (23 operations; 21 patients) were reviewed retrospectively. The mean age of the patients in this series was 30 years and the mean followup was 5 years. On subjective evaluation, 13 operations achieved a definite improvement, five showed slight improvement, and two had no improvement (three operations were excluded). Arthroscopic surgery, as a relatively low risk technique, combined with early functional rehabilitation, can be used to achieve satisfactory results in patients with hemophilic arthropathy.

Adolescent↗
PubMed1995

The effect of knee flexion and quadriceps contraction on the axial view of the patella.

Axial views of the patella are standard in the investigation of anterior knee symptoms, and many investigators use congruence angles and patellar tilt in determining the diagnosis and appropriate treatment. A variety of different methods are used to obtain axial radiographs of the patella, but they are static representations of a dynamic phenomenon. The effect of quadriceps contraction on these indices has not been well defined. The purpose of this study was to compare the 30 degree axial view of the patella with the 45 degree axial view of the patella and to study the effect of quadriceps contraction on the 30 degree axial radiograph of the patella. Forty knees with normal patellofemoral joints and 20 knees with patellar subluxation were radiographed using 30 degree axial views of the patella with the quadriceps relaxed and contracted and with 45 degree axial views with the quadriceps relaxed. There was no significant difference in the sulcus or congruence angles between the 30 and 45 degree axial view in either the control or the patellar subluxation group. Contraction of the quadriceps did not cause a significant or consistent alteration in the congruence angles in either group. With quadriceps contraction, 55% of patients will centralize the patella, whereas 40% will actually increase lateral tracking or subluxation. In conclusion, the 30 degree axial view of the patella is equivalent to the 45 degree axial view in the assessment of patellar subluxation. Quadriceps contraction does not alter the congruence angles obtained in these axial views in a significant or consistent manner.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

[An experimental study on early changes of articular cartilages in subluxated patella of rabbits].

The pathogenesis and clinical progress of chondromalacia patellae have not been well studied in experimental models. We, therefore, studied the patellar subluxation produced experimentally in rabbit knees. In this model, sequential changes of the patellar cartilage were followed by simple X-rays, CT, macroscopic, histologic and scanning electron microscopic examinations up to 32 weeks. Pathological changes extending from horizontal fissures in the middle to the deep layers of the patellar cartilage and thinning of the subchondral bone were found at about six weeks after operation. The early changes of chondromalacia patellae were mostly what is called the basal degeneration, which was presumably attributed to the shearing stress on the articular cartilage. The sequential changes were not very remarkable; none of the rabbits developed OA changes by thirty-two weeks after operation. From these findings, we have that the cartilaginous changes in chondromalacia patellae progress very slowly which probably result from the vigorous repair by the cartilage and also from the acquisition of adaptability on the patellofemoral joint.

Animals↗
PubMed1989

Conservative treatment of patellofemoral subluxation.

As pointed out in the preface of this book, patellofemoral subluxation is probably the most common knee problem seen in many orthopedists' offices today. Whereas the other authors have emphasized the anatomy and diagnosis, this article should serve as a dry but basic instruction on the exercise program that has been used in our clinic. We have had a success rate with this program of approximately 80 per cent. Certainly not all of the 20 per cent that fail require surgery. The classic exercises are quadricep sets, straight leg raises, hip abductors, hip adductors, hip flexors, and hamstring stretches, which have endured the test of time. The prevention of flexion extension activity, such as running the stadium stairs in order to strengthen the quadriceps of the patient with patellofemoral subluxation should be emphasized. Complications of conservative treatment, such as low back pain, iliopsoas tendinitis, and muscle soreness and the treatment of these is described. Finally, the importance of stretching the hamstring muscles is a cornerstone in the treatment of patellofemoral problems. Likewise, a tight IT band can put abnormal stress on the lateral aspect of the patella. In this article I have tried to point out our approach to conservative treatment of patellofemoral subluxation.

Exercise Therapy↗
PubMed2003

Electromyography of the quadriceps in patellofemoral pain with patellar subluxation.

This study compared muscle activity and timing of gait phases during functional activities in 13 subjects with patellofemoral pain associated with lateral subluxation and in 11 subjects with healthy knees. Fine wire electromyography recorded activity in the vastus lateralis and vastus medialis oblique during walking and ascending and descending stairs. Subjects were filmed to divide the activities into phases and determine timing. The vastus medialis oblique and vastus lateralis had similar patterns during all activities. Subjects with patellofemoral pain had significantly increased activity in the vastus medialis oblique and vastus lateralis compared with the healthy subjects during the most demanding phases of the gait cycle, suggesting a generalized quadriceps weakness in the patients with patellofemoral pain. Timing differences were seen in walking and stair ascending with the subjects with patellofemoral pain spending significantly more time in stance compared with the healthy subjects. This may be an attempt to reduce the load on weak quadriceps. These data reflect a generalized quadriceps muscle weakness, rather than the prevailing theory of quadriceps muscle imbalance as an etiology of patellofemoral pain. Therefore, we support the practice of strengthening the entire quadriceps muscle group, rather than attempting to specifically target the vastus medialis oblique.

Adolescent↗
PubMedDate not supplied

Imaging features of avulsion injuries.

Avulsion injuries are common among participants in organized sports, especially among adolescent participants. Imaging features of both acute and chronic avulsion injuries of the pelvis, knee, ankle and foot, shoulder, and elbow were evaluated to help distinguish these injuries from more serious disease processes such as neoplasm and infection. At radiography, acute injuries (ie, those resulting from extreme, unbalanced, often eccentric muscular contractions) may be associated with avulsed bone fragments, whereas subacute injuries have an aggressive appearance that may include areas of mixed lysis and sclerosis. Chronic injuries (ie, those resulting from repetitive microtrauma or overuse) or old inactive injuries may be associated with a protuberant mass of bone and may bear a striking resemblance to a neoplastic or infectious process. Although not usually required, computed tomography is helpful in the diagnosis if radiographic findings are equivocal or if the injury is not in the acute phase. MR imaging is best suited for the evaluation of injuries to muscles, tendons, and ligaments. Recognition of characteristic imaging features and familiarity with musculotendinous anatomy will aid in accurate diagnosis of avulsion injuries.

Acute Disease↗
PubMed1986

The evaluation of patellofemoral pain using computerized tomography. A preliminary study.

There are well-recognized limitations of conventional axial radiographs of the patellofemoral joint in assessing patients with peripatellar pain, particularly in the first 20 degrees of knee flexion. Computerized tomography (CT) was used, therefore, to evaluate 20 patients with persistent patellofemoral pain and ten asymptomatic volunteers. Multiple midpatellar images were obtained between zero degrees and 30 degrees -40 degrees (sometimes 40 degrees) of flexion, with and without maximal quadriceps contraction. Three distinct patterns of malalignment were identified. When compared to controls, 11 patients had lateralized patellae based on high-congruence angles in extension. With progressive flexion to 30 degrees, all but one reduced into the trochlea. This group was subdivided into those lateralized with or without associated patellar tilting. There were seven patients whose patellae progressively tilted between zero degrees and 30 degrees of flexion while remaining centered in the trochlea. Anatomic differences demonstrated by CT appear to be a factor in distinguishing these groups. Computerized tomography may be the optimal method of radiographically evaluating the patellofemoral joint. Patients have been identified with lateralized patellae in extension that subsequently become congruent by 30 degrees of flexion and therefore may not be appreciated on traditional radiographs. An awareness of different patterns of malalignment is a significant advantage of computerized tomography when planning selective surgical realignment for these patients.

Adolescent↗
PubMedDate not supplied

Correlation of joint line tenderness and meniscal lesions in patients with acute anterior cruciate ligament tears.

We sought to evaluate the accuracy with which joint line tenderness is associated with meniscal lesions in knees with acute anterior cruciate ligament tears. The physical assessment of joint line tenderness was performed at a mean of 8 days after the initial injury in 173 patients who subsequently underwent anterior cruciate ligament reconstruction. Identification of meniscal lesions was documented at the time of anterior cruciate ligament reconstruction. Eighty-nine patients (51%) had medial joint line tenderness; of this subgroup, 40 (45%) had a medial meniscal tear. Eighty-four patients (49%) had no medial joint line tenderness; of this subgroup, 29 (35%) had a medial meniscal tear. Fifty-nine patients (34%) had lateral joint line tenderness; of this subgroup, 34 (58%) had a lateral meniscal tear. One hundred fourteen patients (66%) had no lateral joint line tenderness; of this subgroup, 56 (49%) had a lateral meniscal tear. Medical joint line tenderness was 44.9% sensitive and 34.5% specific predicting medial meniscal injury. Lateral joint line tenderness was 57.6% sensitive and 49.1% specific in predicting lateral meniscal injuries. Therefore, we determined that the presence or absence of joint line tenderness in patients with an acute anterior cruciate ligament tear is not a reliable criterion to predict the likelihood of an associated meniscal tear.

Acute Disease↗
PubMed1992

[Isokinetic torque of the knee extensor and flexor in patients with recurrent patellar dislocation].

UNLABELLED: In order to establish the role of muscle strength in the recurrent dislocation of the patella, an isokinetic study was performed using BIODEX, by which the concentric (CC) and passive eccentric (PEC) torques of the quadriceps and hamstrings were measured. The angle velocity was set at 30 degrees and 90 degrees/sec. The subjects were divided into three groups: (I) non-surgical, (II) surgical and (III) normal control. In each group 20 knees were tested, and the following results were obtained. 1. Peak torque: At either 30 degrees/sec or 90 degrees/sec of velocity, it was significantly smaller in group I. On the other hand, the torque in group II was similar to that of group III. 2. E/C (eccentric torque/concentric torque) ratio: PEC was divided by CC to express a muscular strength balance. At 30 degrees/sec velocity, group I showed a significantly high E/C ratio. CONCLUSION: The knees with recurrent dislocation of the patella exhibited significantly lower peak torque and irregular curve patterns. The muscle strength, has been restored to a near-normal level in the surgical group, therefore, the muscle weakness in this disorder can be considered to be a secondary factor. The eccentric torque appeared to play a major role in the development of recurrent dislocation of the patella.

Biomechanical Phenomena↗
PubMed2003

Posterior dislocation after posterior stabilization TKA.

Posterior dislocation after primary total knee arthroplasty is a rare but serious complication. The authors described an 85-year-old man receiving bilateral total knee arthroplasty, which achieved good flexion arc immediately. Posterior dislocation occurred on right knee one month after operation, which was treated by close reduction and casting. Dislocation recurred in combination with infection. The mechanism of dislocation was checked under vision when performing open reduction and debridement. The tibial spine escaped from femoral cam in slight flexion and external rotation due to flexion laxity and biceps tethering. On the way to pursuit higher flexion angle, which is beyond the ordinary daily demand, excessive soft tissue release and bone resection seems to b e compromised. Flexion instability alsooccurs out of purpose, accompanied with increased risk of dislocation.

Aged↗
PubMed1994

MR diagnosis of complete tears of the anterior cruciate ligament of the knee: importance of anterior subluxation of the tibia.

OBJECTIVE: The primary role of the anterior cruciate ligament is to resist anterior subluxation of the tibia. When the ligament is torn, the tibia is free to sublux anteriorly when the leg is pulled forward. In addition to visualizing the anterior cruciate ligament directly, MR imaging can show joint alignment. The purpose of this study was to test the efficacy of MR images of anterior subluxation of the tibia for diagnosing complete tears of the anterior cruciate ligament. MATERIALS AND METHODS: We evaluated the records of 120 consecutive patients who underwent MR imaging of the knee and subsequently had arthroscopy. Arthroscopy showed a complete tear of the anterior cruciate ligament in 21 patients, a partial tear in eight patients, and an intact anterior cruciate ligament in 91 patients. Two radiologists together reviewed the MR images, and interpretation of anterior cruciate ligament integrity was reached by consensus. The anterior cruciate ligament was categorized as intact, completely torn, or partially torn on the basis of conventional MR imaging criteria. The degree of anterior subluxation of the tibia was measured on a separate occasion in random order by a radiologist who used a sagittal section through the middle of the lateral femoral condyle. On the selected image, two vertical lines parallel to the left and right margins of the image frame were drawn tangent to the posterior cortical margins of the lateral femoral and tibial condyles. Anterior subluxation of the tibia was determined by the distance in millimeters between these two lines and measured with calipers by using the 5-cm scale on the images. Measurements were considered reliable only to one half of the smallest increment of this scale (i.e., 5 mm). Accordingly, tibial subluxation (x) was measured in 5-mm increments, with x < or = 0 mm designated grade 0, 0 mm < x < or = 5 mm designated grade 1, 5 mm < x < or = 10 mm designated grade 2, and so forth. RESULTS: Conventional MR imaging criteria had 90% sensitivity and 94% specificity for diagnosing complete tears of the anterior cruciate ligament. According to the receiver-operating-characteristic (ROC) curve, anterior subluxation of the tibia greater than 5 mm (grade 2 or greater) was considered to be the optimal threshold (sensitivity, 86%; specificity, 99%) for diagnosing complete tears of the anterior cruciate ligament. Notably, none of the six false-positive diagnoses of complete tears by conventional criteria (three partial tears and three intact ligaments at arthroscopy) were misdiagnosed when tibial subluxation was used as the diagnostic criterion. Subluxation greater than 5 mm can be falsely negative with chronic tears of the anterior cruciate ligament (n = 2) or when a displaced bucket-handle tear of the lateral meniscus blocks anterior subluxation of the tibia (n = 1). CONCLUSION: An anterior tibial subluxation greater than 5 mm (grade 2 or greater) is a simple objective measurement that serves as a helpful adjunctive sign in the diagnosis of complete tears of the anterior cruciate ligament. This sign also offers improved discrimination of complete from partial tears of the anterior cruciate ligament.

Adult↗