[Vertical intrapatellar restraint in patellar dislocation, patellar tissue insufficiency and patellar chondropathy (author's transl)].
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Adult↗
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Locked lateral patellar dislocation: a rare case of irreducible patellar dislocation requiring open reduction.
Irreducible patellar dislocations are rare injuries, but those that do occur are mainly directed intra-articularly. In this case, a 53-year-old woman sustained a locked lateral patellar dislocation when falling from a chair. A preoperative CT-scan revealed bony avulsions at the insertion of the vastus medialis muscle, the medical retinaculum, and partial disruption of the ligamentum patellae from the apex patellae. Open reduction was necessary and the torn structures were reattached with anchor systems and sutures. Postoperative management included intensive physiotherapy. At 1 year after surgery, the patient was without swelling or pain and had a normal gait, but flexion was restricted to 120 degrees. All postoperative radiographs showed the patella correctly placed in the femoral groove.
Accidental Falls↗
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↗
[Old unreduced traumatic patellar dislocation].
The old unreduced traumatic patellar dislocation is very rare and the results of the treatment are not always satisfactory. We report a 11 year-old boy with an unreduced patellar dislocation and a healed ipsilateral femoral fracture. The dislocation was reduced by an operative procedure. A long leg cast was applied for 6 weeks then the knee exercises were started. One year after surgery, he still has satisfactory results. This case suggests that if the dislocation is not of long duration and degenerative changes are absent in the patella and the knee joint, open reduction may be helpful in the treatment of old unreduced traumatic patellar dislocations. .
Child↗
MR imaging of patellar dislocation and relocation.
Patellar dislocation and relocation (PDR) typically occurs suddenly after trauma or torsional stress on the extensor mechanism. Clinical evaluation after patellar dislocation/relocation usually reveals a swollen knee that is difficult to examine. Radiographs may show hemathroses and a minority of patients will have a chip fracture of the patella. Magnetic resonance (MR) imaging features seen with PDR include disruption or sprain of the medial retinaculum, lateral patellar tilt or subluxation, lateral femoral condylar and medical patellar osseous contusions, osteochondral injury, damage to Hoffa's fat pad, and joint effusion. Up to one third of patients will also show concomitant injury to the major ligaments of the knee or menisci. Without repair of the primary injury, redislocation occurs in greater than one half of patients. Consequently, surgical correction is often advocated. This article reviews the factors predisposing to PDR, the activities associated with PDR, the clinical, radiographic, and MR imaging features of PDR, and (briefly) therapy for this injury.
Humans↗
[Biomechanics and semiology of transient lateral patellar dislocation: reliability of magnetic resonance diagnosis].
Transient patellar dislocation is a rare finding. It is usually due to direct trauma in mediolateral direction or to indirect trauma related to violent quadriceps muscle contraction. The clinical diagnosis of transient forms is usually rather difficult because the associated signs (hemarthros and pain at the joint and/or at the vastus medialis insertion) are not specific. Conventional radiography and CT are very accurate in bone studies, but exhibit major limitations in the detection of capsular injuries with intramedullary and/or cartilaginous bone involvement. We investigated MR diagnostic reliability in the study of the injuries caused by transient patellar dislocation. 526 MR examinations of the knee were reviewed retrospectively; fifteen of them were positive for transient patellar dislocation. We used a .5 T superconductive MR unit with a circumferential extremity coil. Axial, coronal and sagittal T1-weighted spin echo, T2*-weighted gradient echo and axial STIR images were acquired. The following criteria were considered specific for the diagnosis of former lateral patellar dislocation: retinacular changes; patella site; signal intensity changes in femoral and patellar intramedullary bone; joint effusion; cartilage and subchondral bone changes. All the patients with transient patellar dislocation had hemarthros with inner retinaculum involvement. The femoropatellar joint was incongruous in 115 cases; patellar subluxation was external in 8/11 patients and lateral in the remaining 3 patients. Medullary bruises were found in 8/15 cases and cartilage injuries in 13/15. Finally, other joint components, such as the posterior horn of the medial meniscus or the anterior cruciate ligament were involved in 6/13 cases. Arthroscopy was performed in 6 patients with associated injuries and confirmed all MR findings (100% agreement). To conclude, in our experience MRI was a very reliable tool to study the injuries due to transient patellar dislocation because it showed specific changes and possible associated traumas, which helps choose the most suitable treatment.
Adolescent↗
Patellar dislocation after total knee arthroplasty.
BACKGROUND: Patellar problem is an important cause of nonseptic failure of the current condylar design of total knee arthroplasties. Patellar dislocation after total knee arthroplasty is infrequent but can cause disabling symptoms. METHODS: From March, '84 to July, '92, 1652 total knee arthroplasties were performed at this Hospital. Of these 1100 knees in 978 patients were available to be followed up regularly at the Outpatient Department. Eleven cases of patellar dislocation after total knee arthroplasty were encountered during follow-up. Among these patients, nine patients had received operation at this Hospital; the other two patients had been referred here by the other hospitals. All 11 patients had been treated with surgical methods: proximal realignment of the quadriceps alone in 6 knees, lateral retinacular release combined with revision of the malaligned components in 2 knees, combined proximal and distal realignment in 2 knees and patellar tendon transfer in 1 knee. RESULTS: After an average follow-up of 21.8 months, from April, '84 to April, '93, there was one redislocation, unfortunately caused by trauma. Using the average knee rating scale of the Hospital for Special Surgery, New York, USA, the results of 90.5 were satisfactory and encouraging. CONCLUSIONS: Patellar dislocation after total knee arthroplasty can cause disabling symptoms, including pain, weakness, limited range of motion, extension lag and difficulty when climbing up or down stairs. The cause of patellar dislocation after total knee arthroplasty was error in surgical technique in this series. Revision of the component should be performed in those with malaligned component. Proximal realignment is recommended in those with quadriceps imbalance. Distal realignment is recommended only when proximal realignment alone has failed to restore proper patellar tracking, this should be carried out with great caution due to the potential for serious complications.
Aged↗
Transient lateral patellar dislocation: diagnosis with MR imaging.
OBJECTIVE: Transient lateral patellar dislocation is frequently difficult to diagnose accurately on the basis of clinical findings. Accordingly, we studied the MR findings in 26 cases to determine if MR imaging is useful in establishing the diagnosis. MATERIALS AND METHODS: A retrospective review of 1450 MR examinations of acutely injured knees was performed to determine the MR findings resulting from transient lateral patellar dislocation. A distinctive constellation of MR findings reflecting the known mechanism of injury indicative of transient lateral patellar dislocation was found in 26 patients. Patellar dislocation was not clinically suspected before imaging in 19 (73%) of these 26 patients; most patients had been referred for suspected injury of the cruciate ligaments or menisci. Axial, sagittal, and coronal MR images were obtained in all patients, and all had clinical follow-up. Correlation of MR findings with surgical findings was possible in six. RESULTS: Specific components of the constellation of MR findings included disruption or sprain of the medial retinaculum in 25 (96%) of 26 patients, lateral patellar tilt or subluxation in 24 patients (92%), lateral femoral condyle contusion in 21 patients (81%), osteochondral injury in 15 patients (58%), and joint effusion in all 26 patients (100%). Concomitant injury to major ligaments or menisci was present in eight (31%). CONCLUSION: Our findings suggest that patients with transient lateral patellar subluxation have a distinctive constellation of MR findings that can be used to distinguish this entity from other common knee injuries.
Adolescent↗
[Interim results of surgical therapy of patellar dislocation by Insall proximal reconstruction].
Between 1984 and 1991, 57 patients with diagnosis of an acute or recurrent patellar dislocation were treated operatively using proximal realignment with vastus medialis transfer and lateral release (Insall operation). A total of 45 patients (15 with acute and 30 with recurrent patellar dislocation) were reviewed at an average follow-up of 6.5 years (2-9.6 years). The average age at injury was 21.5 years, with a predominance of female patients. Follow-up examination included routine knee examination, clinical review using the modified knee scoring scale of Larsen and Lauridsen, sports activity level and subjective satisfaction. Radiographics from 27 patients (60%) were evaluated. One patient from each group suffered recurrence of patellar dislocation. All patients had stable knee joints and a full range of motion. There was no statistical difference in the pre- and postoperative sports activity level in both groups. Three patients (19.9%) with acute patellar dislocation and seven patients (23.3%) with recurrent patella dislocation had excellent results using the Larsen and Lauridsen score scale. Ten patients (66.6%) with acute and 12 (39.9%) with recurrent dislocation had good results. One patient with recurrent patellar dislocation had a fair result. Subjective evaluation revealed the operative result in 93% of cases as very good, good or satisfactory. Patellofemoral osteoarthritis was seen in 11 (40.7%) of 27 patients. Our results show good clinical results for the treatment of acute patellar dislocation in young, active patients with the proximal realignment procedure. The recurrence rate of patellar dislocation can be reduced for acute and recurrent patellar dislocation. Subjective satisfaction with this procedure is rated very good.
Acute Disease↗
The reliability and validity of knee-specific and general health instruments in assessing acute patellar dislocation outcomes.
BACKGROUND: The most reliable and valid instruments for assessing patient outcome after patellar dislocation have not been identified. HYPOTHESIS: Knee-specific and general health instruments will differ in validity and reliability for patients with patellar dislocation. STUDY DESIGN: Prospective cohort study. METHODS: Subjects consisted of 153 patients with acute patellar dislocation (110 with first-time dislocations and 43 with a history of patellofemoral subluxation or dislocation). We administered the modified International Knee Documentation Committee form, Kujala, Fulkerson, Lysholm, Tegner, Short Form 36, and Musculoskeletal Function Assessment instruments on two separate occasions (test-retest reliability). Validity was assessed by comparing scores of the two groups and by comparing scores of patients with and without recurrent subluxations/dislocations during follow-up. RESULTS: The knee-specific instruments yielded the highest test-retest reliability. The knee-specific and general health instruments identified higher disability levels in the patients with a history of patellofemoral problems than in those with first-time dislocations. The general health instruments identified higher disability levels in patients with patellar dislocation than published norms. The Fulkerson and Lysholm scales were the only instruments to differentiate between patients with and without recurrent subluxations/dislocations. CONCLUSIONS: Knee-specific scales yielded higher reliability coefficients and stronger validity than did general health instruments. Knee-specific, general health, and activity level instruments are complementary and in combination provide a more complete assessment for patients with patellar dislocation.
Adolescent↗
Articular cartilage injury with acute patellar dislocation in adolescents. Arthroscopic and radiographic correlation.
Acute patellar dislocation and relocation produces major forces at the articular surfaces. Articular injury was assessed in 48 patients, 24 boys and 24 girls (mean age, 14 years), with acute, initial, noncontact patellar dislocations. Correlation of the findings of radiographic and arthroscopic examinations was done. Eleven of the 48 patients (23%) had radiologic diagnoses of articular injuries. Thirty-four of the 48 patients (71%) had arthroscopic evidence of articular damage, 32 osteochondral and 2 chondral injuries. Eight of the 28 (29%) arthroscopically identified osteochondral loose bodies (4 to 20 mm) were identified radiologically. Overall, only 11 of the 34 (32%) arthroscopically documented articular injuries were defined by preoperative radiographs. These standard radiographs provided limited information for management decisions. Poor results after patellar dislocation treatment may involve nonrecognition of articular compromise.
Acute Disease↗
Classification of lesions of the medial patello-femoral ligament in patellar dislocation.
The remnants of the medial patello-femoral ligament (MPFL) of 67 knees, 18 with acute patellar dislocation and 49 with chronic patellar dislocation, were studied. The MPFL injuries of the acute cases were categorised into 2 groups: an avulsion tear type and a substantial tear type. The chronic cases were put into 3 groups: those with loose femoral attachment (9 knees), those with scar tissue formation or abnormal scar branch formation (29 knees), and those with no evidence or continuity of the ligament (absent type) (11 knees). It is concluded that incompetence of the medial patello-femoral ligament is a major factor in the occurrence of recurrent patellar dislocation and/or an unstable patella following an acute patellar dislocation.
Acute Disease↗
Articular hypermobility and chondral injury in patients with acute patellar dislocation.
Thirty adolescents with acute, primary patellar dislocation were assessed for a relationship between articular hypermobility and chondral injury. The 15 patients without articular hypermobility had a 2.5 times increased frequency of articular lesions when compared with 15 patients with hypermobility. Assessment of articular hypermobility should be part of the examination in patients with patellar dislocation.
Acute Disease↗
Total knee arthroplasty for neglected permanent post-traumatic patellar dislocation--case report.
Permanent post-traumatic patellar dislocation is a rare entity resulting from recurrent trauma. This uncommon condition is often confused clinically with congenital dislocation of the patella. Treatment options, although not well defined, include observation, various soft tissue and bony procedures for realigning the patella and patellectomy. To our knowledge, this is the first case reporting the use of conventional non-constrained total knee arthroplasty with patellar resurfacing and soft tissue realignment procedure for long-standing patellar dislocation in a single stage. An interesting feature of this case was the patient's ability to function reasonably well for nearly 40 years with a dislocated patella until the development of secondary osteoarthritis, and the surprisingly good recovery after total knee replacement.
Arthrography↗
Patellar dislocation in Rubenstein-Taybi syndrome.
This report describes 11 patients with Rubinstein-Taybi syndrome (RTS) and patellar dislocation. The age at diagnosis of patellar dislocation ranged from birth to 16 years. Ten patients had chronic dislocations and 8 of 11 had bilateral patellar dislocations. Eight patients required surgical stabilization of the patella; most achieved a good outcome with surgical repair. All families reported that the patellar dislocations impaired developmental skills which improved after surgery. Seven of the 11 patients were described as having other joint abnormalities including congenital dislocations and laxity of the joints. Patients with RTS should undergo regular thorough joint examinations, including the knees, because abnormalities may result in delay of attainment of motor skills.
Adult↗
Surgical technique and rationale for medial patellofemoral ligament reconstruction for recurrent patellar dislocation.
This article describes a medial patellofemoral ligament (MPFL) reconstruction procedure using an artificial ligament for recurrent patellar dislocation. The MPFL has been shown biomechanically to be the primary restraint among the medial patellar stabilizers. Although various predisposing factors are involved in lateral patellar dislocation, we believe that the MPFL, as a primary restraint, should undergo primary reconstruction for patellar dislocation. The results of MPFL reconstruction using a mesh-type artificial ligament and medial retinaculum slip coverage for recurrent patellar dislocation were as good as we had expected. In this article, we describe the detailed surgical technique and its rationale. We believe technique has also wide applications in MPFL reconstruction using autogenous tendons.
Arthroscopy↗
Patellar dislocation in army conscripts.
Between 1990 and 1996, 119 Finnish male conscripts underwent operative treatment for patellar dislocation. There were 68 conscripts (58%) with primary and 51 conscripts (42%) with recurrent patellar dislocation. Sixty-five (55%) dislocations occurred during military service, 40 (34%) occurred during sports activities, and 14 (11%) occurred during leisure time. The most common cause of injury was military training at battle exercises (n = 30). The typical injury mechanism was knee valgus rotation on fixed foot and tibia (97 conscripts, 82%). Surgical procedures performed were open in 75 conscripts (63%) and arthroscopically assisted in 44 conscripts (37%). Twenty-three (19%) redislocations occurred during follow-up (mean, 6 years; range, 3-9 years). The subjective outcome of treatment was excellent in 23 (19%), good in 42 (35%), moderate in 44 (37%), and poor in 10 (9%) conscripts. The most common residual complaint was patellofemoral pain (25 conscripts, 21%). Only 42 (35%) conscripts were able to finish their military service normally; fitness classification was decreased in 16 conscripts (13%), and 61 (52%) were temporarily exempted from military service (class E). The results of operative treatment did not differ significantly in conscripts with primary and recurrent dislocation, except for the time of first recurrence, which was significantly longer in conscripts with primary than with recurrent dislocation (27 versus 9 months). Patellar dislocation is the most common form of severe knee injury among conscripts and significantly hampers military service. Operative treatment yields only satisfactory results. Preventive measurements should be considered. A suggested algorithm for the treatment and classification of acute and recurrent patellar dislocation among military conscripts is presented.
Acute Disease↗
Acute lateral patellar dislocation at MR imaging: injury patterns of medial patellar soft-tissue restraints and osteochondral injuries of the inferomedial patella.
PURPOSE: To assess magnetic resonance (MR) imaging findings after acute lateral patellar dislocation (LPD) with emphasis on the medial patella restraints and to describe a medial patellar impaction deformity. MATERIALS AND METHODS: Knee MR images obtained within 8 weeks after LPD were evaluated for medial retinacular and medial patellofemoral ligament (MPFL) disruption, vastus medialis obliquus (VMO) edema and/or elevation, and other derangements. One hundred patients with no evidence of prior LPD were evaluated as controls. The Student t test was used for statistical comparisons. RESULTS: Eighty-two examinations were performed in 81 patients with LPD (mean age, 20 years; age range, 9-57 years). Seventy-six percent (62 of 82 examinations) showed medial retinacular disruption at its patellar insertion; 30% (25 of 82), at its midsubstance. The MPFL femoral origin was identified in 87% (71 of 82); of these, 49% (35 of 71) showed injury. Forty-eight percent (39 of 82) showed more than one site of injury to the medial stabilizers; 45% (37 of 82) showed edema or hemorrhage at the inferior VMO. Mean VMO elevation in the coronal plane of the adductor tendon was 2.2 cm, with a range of 0.6-4.5 cm (in control subjects, 0.9 cm; range, 0.1-2.5 cm; P <.001). At the inferomedial patella, 70% (57 of 82) of LPD examinations showed osteochondral injury and 44% (36 of 82) showed concave impaction deformity (0 of 100 control subjects). Other examination findings in LPDs included contusions of the lateral femoral condyle (66 [80%] of 82 examinations) or medial patella (50 [61%] of 82), intraarticular bodies (12 [15%] of 82), effusion (45 [55%] of 82), medial collateral injury (nine [11%] of 82), and meniscal tear (nine [11%] of 82). CONCLUSION: Injury to the medial retinaculum, MPFL, and VMO may be identified at MR imaging after acute LPD. Concave impaction deformity of the inferomedial patella is a specific sign of prior LPD.
Adult↗