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PubMed2002

The tolerance of the human hip to dynamic knee loading.

Based on an analysis of the National Automotive Sampling System (NASS) database from calendar years 1995-2000, over 30,000 fractures and dislocations of the knee-thigh-hip (KTH) complex occur in frontal motor-vehicle crashes each year in the United States. This analysis also shows that the risk of hip injury is generally higher than the risks of knee and thigh injuries in frontal crashes, that hip injuries are occurring to adult occupants of all ages, and that most hip injuries occur at crash severities that are equal to, or less than, those used in FMVSS 208 and NCAP testing. Because previous biomechanical research produced mostly knee or distal femur injuries, and because knee and femur injuries were frequently documented in early crash investigation data, the femur has traditionally been viewed as the weakest part of the KTH complex. However, the relative risk of hip injuries to the risks of knee and thigh injuries in frontal crashes of late-model vehicles suggests that this may not be the case. This study investigated the frontal-impact fracture tolerance of the hip in nineteen tests performed on the KTH complexes from sixteen unembalmed human cadavers. In each test, the pelvis was rigidly fixed by gripping the iliac wings with the thigh-to-pelvis angle set to correspond to a standard automotive-seated posture. A dynamic load was applied to the knee along the axis of the femur at loading rates that are representative of knee-to-knee bolster impacts in frontal crashes. Rigidly fixing the pelvis minimizes inertial effects along the KTH complex, which results in similar force levels along the KTH complex. Consequently, in these tests, the weakest part of the KTH complex failed first. All seventeen fixed pelvis tests that produced usable data resulted in acetabular fractures at an average applied force of 5.70 kN (sd = 1.38 kN). The lack of injuries to the femoral shaft and distal femur in these tests indicates that the tolerance of the hip is less than that of the femur under frontal-impact loading. To further explore the tolerance of the femur relative to the hip, thirteen uninjured knee/femur specimens from seven cadavers previously used in hip tolerance tests were dynamically loaded. In these tests, the head of the femur was supported in a fixed "acetabular cup" to minimize inertial effects, and load was applied at the knee along the axis of the femur. All of these tests resulted in femoral neck fractures. Two tests also resulted in fractures to the femoral shaft. The average tolerance of the femoral neck from these tests is 7.59 kN (sd = 1.58 kN), which is significantly higher (p < 0.05) than the tolerance of the acetabulum. These results suggest that the mid and distal portions of the femur have a higher tolerance under these loading conditions than the pelvic and femoral portions of the hip.

Journal Article↗
PubMed1991

[Genucom knee analysis after introduction of Dacron prostheses in knees with isolated rupture of the anterior cruciate ligament. 44 consecutive cases].

During the period 1. December 1984 to 30. November 1986, reconstructive operations were performed on 44 patients with isolated unilateral rupture of the anterior cruciate ligament. The patients suffered from chronic insufficiency of the knee with episodes of dislocation. The anterior cruciate ligament was reconstructed with a synthetic Dacron prosthesis and the postoperative stability of the knee was registered by means of a Genucom knee analysis system and manual tests for stability. Reconstruction involved an increase in the average Lysholm score from 63 preoperatively to 91 postoperatively. The activity of the patients, as measured by Tegner scoring, improved in 30 cases but only 14 patients stated that they had achieved the same level of activity as before rupture of the cruciate ligament. Sixteen out of the 44 patient patients, according to the Genucom analysis, obtained an antero-posterior stability which corresponded to that in the healthy knee. No correlation was found between possible objective stability measured by Genucom and the patients Lysholm scoring. 20% (9/44) of the patients sustained rupture of the Dacron prosthesis after an average of 11 months. The present authors consider that the quality of the prosthetic material should, therefore, be improved.

Adolescent↗
PubMed1979

A long-term prospective study of the Hauser and Roux-Goldthwait procedures for recurrent patellar dislocation.

In a prospective study extending from 1966 to 1974, the results of the Hauser procedure were compared with the Roux-Goldthwait procedure for the correction of recurrent dislocations of the patella. In 87 knees in 75 patients, repaired consecutively and in a random manner with one procedure or the other, 100% retrieval was achieved. The average follow-up period was 7.7 years. Significant complications, though not necessarily of long term, occurred in 24 of 47 knees receiving Hauser repairs as compared with 6 of 40 knees in the Roux-Goldthwait group. Satisfactory long-term results were obtained in 72% with the Hauser technique and 93% with the Roux-Goldthwait technique.

Adolescent↗
PubMed1987

A case of superior dislocation of the patella.

A 56-year-old woman with arthrosis of the knee sustained a fixed superior dislocation of the patella from a minor trauma. Closed reduction was performed. Only 3 other cases have been found reported in the literature.

Female↗
PubMed1990

[Experimental hip dysplasia in the rabbit].

Neglected cases of congenital dislocation of the hip (CDH) always present with profoundly interesting X rays and pathoanatomical changes. Because of progressive dysplastic change, it is difficult to determine clinically at what stage a patient can not have reconstructive surgery. We used an animal model to induce hip dysplasia in order to understand the mechanism of dislocation and to demonstrate the dysplastic changes at various ages of dislocation. We used a plastic tube to immobilize the left knee of one week old New Zealand white rabbits in the extension position. Fifty-five rabbits in a natural history group were examined physically, radiographically and pathologically every month, until five months old. Ten rabbits were also studied by computed tomography before sacrifice. Forty-two rabbits which had been immobilized for more than 2 months were selected to determine the changes in their left hips. Tenotomy of the hamstrings of the left knee was performed in another 20 rabbits, which were then immobilized in the same way until 2 months old. The changes in their left hips were also determined and compared with the changes of former group. In our study, immobilization of the left knee of rabbits can induce dislocation, subluxation or no change. Tenotomy of the hamstrings can decrease the incidence of dislocation and subluxation, but cannot avoid their occurrence. In long-term observation of rabbits with dislocation and subluxation, we found that there are more dysplastic and degenerative changes in older rabbits. Computed tomography proved to be an effective evaluation tool of the size of dysplastic acetabulum and femoral head.

Animals↗
PubMed1980

[Classification and clinical diagnosis of lesions to the capsule and the ligaments of the knee point (author's transl)].

A classification of lesion of the capsule and ligaments of the knee joint can be related to the possible dislocation of the tibial head due to the injury. Analysing the dislocation the injured structures can be determined. This classification provides a better planning for the reconstruction of fresh and old injuries. A proper knowledge of the anatomy and the biomechanics of the knee joint is essential. Experimental and clinical experience over the last decade show that a simple classification in lateral, medial, anterior and posterior instability is inadequate. Therefore a more specific classification is recommended. Under this aspect history and clinical findings are of utmost importance for the diagnosis of injuries to the capsule and the ligaments of the knee joint.

Bursa, Synovial↗
PubMed1993

Prior lateral patellar dislocation: MR imaging findings.

PURPOSE: To illustrate the constellation of magnetic resonance (MR) findings that suggest prior patellar dislocation. MATERIALS AND METHODS: A computer search of all MR examinations of the knee with a coded diagnosis of patellar dislocation performed between February 1988 and October 1990 disclosed 22 cases (11 male and 11 female patients, aged 1-70 years). RESULTS: Eighteen cases (82%) demonstrated hemarthrosis, medical retinacular disruption, and contusion of the lateral femoral condyle. In 11 cases, the patella was displaced from the trochlear sulcus, but in no patient was there complete dislocation at the time of imaging. Axial short-inversion-time inversion-recovery (STIR) images demonstrated subtle subchondral and cancellous signal intensity abnormalities that were often poorly appreciated on T2-weighted images. In 11 cases, patellar dislocation was not suspected before MR imaging. CONCLUSION: Hemarthrosis, medial patellar and lateral femoral contusion, and retinacular disruption suggest prior lateral patellar dislocation. Because of its sensitivity to subtle intraosseous signal abnormality, axial STIR imaging is a valuable adjunct in the evaluation of the acutely injured knee.

Contusions↗
PubMed2005

Locked lateral patella dislocation with generalized ligamentous laxity after arthroscopic lateral release of the knee.

We describe the case of a 14-year-old boy with patellar instability on both sides resulting from ligamentous hyperlaxity and dysplasia of the lateral femoral condyle who had previously undergone an arthroscopic lateral release as well as plication of the medial capsule. The patient presented to our clinic 2 years after surgery with a locked lateral patella dislocation on the left side. The surgical correction involved a substantial open lateral release including an excision of the scar tissue and stabilization of the patella in the patellofemoral groove by tibial tubercle medialization and plication of the medial capsule. Six months after surgery, the patient achieved a Lysholm score of 90 points and clinical examination indicated a stable knee with a centralized patella without any evidence of subluxation or dislocation. Open lateral release with partial resection of the lateral retinaculum, medial reconstruction, and tibial tubercle osteotomy was the procedure of choice in this patient with habitual patella dislocation caused by generalized ligamentous laxity.

Adolescent↗
PubMed2004

Cartilage lesions of the patella in recurrent patellar dislocation.

BACKGROUND: The etiology of patellar cartilage lesions in recurrent patellar dislocation has been poorly understood. HYPOTHESIS: The pathology of cartilage lesions of the patella accompanied by recurrent patellar dislocation can be analyzed. STUDY DESIGN: Series of case reports. METHODS: In 70 knees from 57 patients with recurrent patellar dislocation, the cartilage lesions of the patella were examined using arthroscopy and/or macroscopic observation. The average age of the patients was 22 years (range, 13 to 40 years). Lesions that involved only softening were not included. RESULTS: Sixty-seven knees (96%) had articular cartilage lesions of the patella, and only 3 knees had no change. Fissuring was observed in 53 knees (76%). The most common site of fissuring was on the central dome. There were basically two types of fissuring: multiple longitudinal fissuring and marginal/radial fissuring. Fibrillation and/or erosion were observed in 54 knees (77%). Of these, 40 knees had fissuring and 14 did not have fissuring. The main site of fibrillation and/or erosion was the medial facet. CONCLUSIONS: Cartilage lesions of the patella in recurrent patellar dislocation cases were very common. Fissuring was observed mainly on the central dome, and fibrillation and/or erosion were observed mainly on the medial facet.

Adolescent↗
PubMed1998

Flexion instability after primary posterior cruciate retaining total knee arthroplasty.

Between 1990 and 1995, 25 painful primary posterior cruciate ligament retaining total knee arthroplasties were revised for flexion instability. These patients shared typical clinical presentations that included a sense of instability without frank giving way, recurrent knee joint effusion, soft tissue tenderness involving the pes anserine tendons and the retinacular tissue, posterior instability of 2+ or 3+ with a posterior drawer or a posterior sag sign at 90 degrees flexion, and above average motion of their total knee arthroplasty. The primary total knee arthroplasty was performed for osteoarthritis in 23 patients and rheumatoid arthritis in two patients. There were 13 male and 12 female patients and their mean age was 65 years (range, 35-77 years). Before the revision operation, Knee Society knee scores averaged 45 points (range, 17-68 points) and function scores averaged 42 points (range, 0-60 points). Twenty-two of the knee replacements were revised to posterior stabilized implants and three underwent tibial polyethylene liner exchange only. Nineteen of the 22 knee replacements revised to a posterior stabilized implant were improved markedly after the revision surgery. Only one of three knee replacements that underwent tibial polyethylene exchange was improved. After the revision for flexion instability, Knee Society knee scores averaged 90 points (range, 82-99 points) and function scores averaged 75 points (range, 45-100 points) for the 20 knees with a successful outcome. This study suggests that flexion instability can be a cause of persistent pain and functional impairment after posterior cruciate ligament retaining total knee arthroplasty. A revision operation that focuses on balancing the flexion and extension spaces, in conjunction with a posterior stabilized knee implant, seems to be a reliable treatment for symptomatic flexion instability after posterior cruciate retaining total knee arthroplasty.

Adult↗
PubMedDate not supplied

Instability of the proximal tibiofibular joint.

Injury to the proximal tibiofibular joint is typically seen in athletes whose sports require violent twisting motions of the flexed knee. Instability of this joint may be in the anterolateral, posteromedial, or superior directions. With acute injury, patients usually complain of pain and a prominence in the lateral aspect of the knee. A closed reduction should be attempted in patients with acute dislocation. If this is unsuccessful, open reduction and stabilization of the joint with repair of the injured capsule and ligaments can be done. Patients with chronic dislocation or subluxation report lateral knee pain and instability with popping and catching, which may be confused with lateral meniscal injury. Symptoms of subluxation may be treated nonsurgically with physical therapies such as activity modification, supportive straps, and knee strengthening. For patients with chronic pain or instability, surgical options include arthrodesis, fibular head resection, and proximal tibiofibular joint capsule reconstruction.

Athletic Injuries↗
PubMed1980

Preliminary results of the Sheehan total knee prosthesis.

A review of 50 knees in 42 patients operated upon between August, 1973 and November, 1976 is presented. Following initial good results, problems have been encountered with the passage of time. Complications due to design faults, selection, and technical pitfalls are analysed. Patients who have grossly unstable and deformed knees are not suitable for this type of prosthesis. The high density polyethylene central flange in the tibial component is not strong enough to withstand valgus or varus forces. Full correction of valgus, varus, or flexion deformities is essential if late complications are to be avoided. Associated external rotation deformities in grossly valgus knees have to be fully corrected to prevent late dislocation of the patella. Our conclusion is that at present there is a place for both the hinged and hingeless type of prosthesis in total knee replacement.

Adult↗
PubMed2004

Patellofemoral relationships and cartilage breakdown.

We evaluated the association between patellofemoral relationships and cartilage lesions in patients (age range 15-49) with anterior knee pain without patellar dislocation (n = 24) and in patients with isolated meniscal rupture without a high energy trauma (n = 21). The position of the patella was assessed from knee radiographs, and cartilage lesion was graded and mapped at arthroscopy. In subjects with lateral patellar cartilage lesion the patella tilted laterally (p < 0.01) and was clearly laterally displaced (p < 0.001), compared to those without patellar cartilage lesion. In subjects with central patellar cartilage lesion the patella located high according to the Insall-Salvati index (p < 0.01) and was somewhat laterally displaced (p < 0.05). Compared to subjects without cartilage lesion in the femoral trochlea, the patella was laterally displaced in subjects with lesion in the lateral trochlea (p < 0.001). In conclusion, our results suggest that specific malalignments predispose to patellofemoral cartilage lesion, but prospective studies are needed to confirm the finding.

Adolescent↗