Degeneration of patellar cartilage in patients with recurrent patellar dislocation following conservative treatment: evaluation with delayed gadolinium-enhanced magnetic resonance imaging of cartilage

Patellar Dislocation in Adolescent Patients: Influence on Cartilage Properties Based on T1ρ Relaxation Times

BACKGROUND

Adolescents who experience a patellar dislocation have an elevated risk of patellofemoral posttraumatic osteoarthritis. Magnetic resonance imaging (MRI)-based T1ρ relaxation times were measured for adolescents to evaluate patellofemoral cartilage after patellar dislocation. Long T1ρ relaxation times are an indicator of cartilage degradation.

HYPOTHESIS

The primary hypothesis is that patellofemoral cartilage T1ρ relaxation times will be elevated in the acute phase after patellar dislocation. The secondary hypothesis is that T1ρ relaxation times will be higher for knees with multiple rather than single dislocations due to repeated traumatic injury.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

In total, 23 adolescents being treated for a recent patellar dislocation, 13 for a first-time dislocation (47 ± 38 days since most recent dislocation) and 10 for multiple dislocations (55 ± 24 days since most recent dislocation), and 10 healthy controls participated in MRI-based T1ρ relaxation time mapping. For multiple regions of the patellofemoral joint, mean T1ρ values were compared between the 3 groups with multiple group comparisons and post hoc tests. T1ρ relaxation times were also correlated against measures of patellofemoral anatomy and alignment for single and multiple dislocations. Statistical significance was set at P < .05.

RESULTS

T1ρ relaxation times were significantly longer for injured knees (single and multiple dislocations) than controls at the medial and central patella and central trochlear groove. For the regions on the patella, significant differences between injured and control knees exceeded 15%. No significant differences were identified between single and multiple dislocations. For the initial dislocation group, T1ρ relaxation times within multiple regions of the patellofemoral joint were significantly correlated with lateral patellar alignment or patellar height.

CONCLUSION

Elevated patellofemoral cartilage T1ρ relaxation times are consistent with a high risk of long-term patellofemoral osteoarthritis for adolescents who experience patellar dislocations. T1ρ relaxation times were elevated for multiple regions of patellofemoral cartilage. T1ρ relaxation times were expected to increase with additional dislocation episodes, but relaxation times after single and multiple dislocations were similar. After a first dislocation, parameters related to patellar maltracking were correlated with cartilage degradation.

Elevated Patellofemoral and Tibiofemoral T1ρ Relaxation Times Following a First Time Patellar Dislocation

OBJECTIVE

The study was performed to evaluate cartilage within the knee following a first-time patellar dislocation, using elevated MRI-based T1ρ relaxation times as an indicator of low proteoglycan concentration. The hypothesis is that MRI-based T1ρ relaxation times for patellofemoral and tibiofemoral cartilage are significantly longer for knees being treated for patellar dislocation than for healthy control knees.

DESIGN

Twenty-one subjects being treated for a first-time, unilateral dislocation of the patella and 16 healthy controls participated in MRI-based T1ρ relaxation time mapping. Mean relaxation times were quantified for patellofemoral and tibiofemoral regions for injured knees, the contralateral knees, and healthy controls. T1ρ values for each region were compared between the 3 groups with generalized estimating equations. Linear regressions were also performed to correlate T1ρ relaxation times with time from injury.

RESULTS

The knees with a disloction had longer T1ρ relaxation times than the contralateral knees and control group at the medial patella and longer relaxation times than the control group at the lateral tibia (P < 0.05). T1ρ relaxation times at the medial patella also decreased with time from injury (r² = 0.21, P = 0.037).

CONCLUSIONS

Compositional changes to cartilage on the medial patella are related to traumatic impact during a dislocation. Potential exists for cartilage properties at the medial patella to improve with time. Cartilage degradation at the lateral tibia is not directly related to traumatic impact. The current baseline data are a starting point to characterize the pathway from a first-time dislocation to progressive cartilage degradation and osteoarthritis.

Recurrent patellar dislocations with patellar cartilage defects: A pain in the knee?

BACKGROUND

Recurrent patellar dislocation in combination with cartilage injures are difficult injuries to treat with confounding pathways of treatment. The aim of this study was to compare the clinical and functional outcomes of patients operated for patellofemoral instability with and without cartilage defects.

METHODS

Eighty-two patients (mean age 28.8 years) with recurrent patellar dislocations, who underwent soft-tissue or bony procedures, were divided into two matched groups (age, sex, follow up and type of procedure) of 41 each, based on the presence or absence of cartilage defects in patella. Chondroplasty, microfracture, osteochondral fixation or autologous matrix-induced chondrogenesis (AMIC)-type procedures were performed depending on the nature of cartilage injury. Lysholm, Kujala, Tegner and Subjective Knee scores of both groups were compared and analysed. Complications and return to surgery were noted.

RESULTS

With a mean follow up of 8 years, there was a significant improvement observed in all the mean postoperative patient-reported outcome measures of both groups, as compared with the preoperative scores (P < 0.05). Comparing the two groups, postoperative Lysholm, Kujala and Subjective knee scores were significantly higher in patients operated without cartilage defects (P < 0.05). Three patients operated for patellofemoral instability with cartilage defects underwent patellofemoral replacement subsequently. The odds ratio for developing complications was 2.53 for patients operated with cartilage defects.

CONCLUSION

Although there is a significant improvement in the long-term outcome scores of patients operated for recurrent patellar dislocation with cartilage defects, the results are significantly inferior compared with those without cartilage defects, along with a higher risk of developing complications and returning to surgery.

Quantitative MRI Musculoskeletal Techniques: An Update

OBJECTIVE. For many years, MRI of the musculoskeletal system has relied mostly on conventional sequences with qualitative analysis. More recently, using quantitative MRI applications to complement qualitative imaging has gained increasing interest in the MRI community, providing more detailed physiologic or anatomic information. CONCLUSION. In this article, we review the current state of quantitative MRI, technical and software advances, and the most relevant clinical and research musculoskeletal applications of quantitative MRI.

T2 mapping and post-contrast T1 (dGEMRIC) of the patellar cartilage: 12-year follow-up after patellar stabilizing surgery in childhood

Background

Cartilage degeneration has been reported after recurrent patellar dislocation. However, effects of surgical stabilization in childhood have not yet been described.

Purpose

To examine the cartilage quality in very young adults operated with a patellar stabilizing procedure due to recurrent patellar dislocation in childhood, and evaluate if cartilage quality correlates with clinical parameters and patient-reported outcomes.

Material and Methods

Seventeen patients were investigated ≥ 5 years (mean = 11.6 years) after patellar stabilizing surgery in childhood. Pre-contrast T2 relaxation times were analyzed in four superficial and four deep patellar cartilage regions of both knees. Two hours after 0.2 mM/kg Gd-DTPA² i.v., post-contrast T1 (T1(Gd)) was analyzed in the same regions. Patient-reported outcomes (KOOS, Kujala, and Tegner scores) and recurrence rates were evaluated.

Results

Comparing operated to healthy side, neither T2 nor dGEMRIC differed between the operated and the reference knee regarding the superficial half of the cartilage. In the deep half of the cartilage, T1(Gd) was shorter in the central part of the cartilage, whereas T2 was longer medially (P < 0.05). A low score in the KOOS subscales Symptom and Sports & Recreation, was correlated to the degenerative changes detected by T1(Gd) (r = 0.5, P = 0.041).

Conclusion

In general, our findings demonstrate good cartilage quality 12 years after patellar stabilizing surgery during childhood. The subtle changes in T2 and T1(Gd) in the deep cartilage layer may be a result of altered biomechanics, although very early degenerative changes cannot be excluded. The short T1(Gd) centrally may reflect lower glycosaminoglycan content, whereas the increase in T2 medially indicates increased cartilage hydration.

Functional properties of native and tissue-engineered cartilage toward understanding the pathogenesis of chondral lesions at the knee: A bovine cadaveric study

Chondral lesions frequently occur in different topographic locations of the knee. This study evaluated the functional properties among the articulating surfaces of the tibiofemoral and patellofemoral joints, and whether neo-cartilage engineered using chondrocytes from different knee locations would reflect these differences. The biomechanical properties of bovine cartilage isolated from eight locations within the tibiofemoral (medial and lateral condyle, medial and lateral tibial plateau) and patellofemoral joints (medial and lateral trochlea, medial and lateral patella) were examined. Tensile Young's moduli (tensile moduli) and aggregate moduli of the medial condyle were lower than those of the medial tibial plateau (6.11 ± 0.89 MPa vs. 7.19 ± 1.05 MPa, p = 0.04 and 354.4 ± 38.3 kPa vs. 419.4 ± 31.3 kPa, p = 0.002, respectively). Patella tensile and compressive moduli were lower than the trochlea (4.79 ± 2.01 MPa vs. 6.91 ± 2.46 MPa, p = 0.01 and 337.4 ± 37.2 kPa vs. 389.1 ± 38.3 kPa, p = 0.0005, respectively). Furthermore, chondrocytes from the above locations were used to engineer neo-cartilage, and its respective properties were evaluated. In neo-cartilage, medial condyle tensile and aggregate moduli were lower than in the medial tibial plateau (0.96 ± 0.23 MPa vs. 1.31 ± 0.31 MPa, p = 0.02, and 115.8 ± 26.0 kPa vs. 160.8 ± 18.8 kPa, p = 0.001, respectively). Compared to trochlear chondrocytes, neo-cartilage formed from patellar chondrocytes exhibited lower tensile and compressive moduli (1.16 ± 0.27 MPa vs. 0.74 ± 0.25 MPa, p < 0.001, and 109.1 ± 24.0 kPa vs. 82.5 ± 18.1 kPa, p < 0.001). A significant degree of disparity in biomechanical properties of the opposing articular surfaces was detected; the medial condyle and patella exhibited inferior properties compared to the opposing medial tibial plateau and trochlea, respectively. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2452-2464, 2017.

Operative Management of Patellar Instability in the United States: An Evaluation of National Practice Patterns, Surgical Trends, and Complications

Background:

Treatment of patellofemoral instability has evolved as our understanding of the relevant pathoanatomy has improved. In light of these developments, current practice patterns and management trends have likely changed to reflect these advancements; however, this has not been evaluated in a formal study.

Purpose:

To determine nationwide patient demographics, surgical trends, and postoperative complications associated with the operative management of patellar instability surgery.

Study Design:

Descriptive epidemiological study.

Methods:

A large private-payer database (PearlDiver) comprising patients covered by Humana and United Healthcare insurance policies was retrospectively reviewed using Current Procedural Terminology (CPT) codes to identify patients who underwent surgery for patellar instability. The study cohort was established by querying for patients billed under CPT codes 27420, 27422, or 27427 while satisfying the diagnostic requirement of patellar instability (International Classification of Diseases–9th Revision codes 718.36, 718.86, or 836.3). Patient demographics, surgical trends, concomitant procedures, and postoperative complications were determined.

Results:

A total of 6190 patients underwent surgical management for patellar instability. Adolescents (age range, 10-19 years) represented 51.5% of cases, and 59.6% were female. The number of patellar instability procedures increased annually over the study period in both the Humana (P = .004, R² = 0.76) and United Healthcare (P = .097, R² = 0.54) cohorts. The most common concomitant procedures were lateral retinacular release (43.7%), chondroplasty (31.1%), tibial tubercle osteotomy (13.1%), removal of loose bodies (10.5%), osteochondral grafting (9.5%), and microfracture surgery (9.5%). Manipulation under anesthesia was required in 4.6% of patients within 1 year. Patellar fracture within 1 year and infection within 30 days occurred in 2.1% and 1.2% of patients, respectively.

Conclusion:

Patellar instability surgery has increased over the past decade. This finding may be attributed to growing clinical evidence to support these procedures as well as increased surgeon familiarity and comfort with these specific techniques. We observed an unexpectedly high rate of concomitant lateral retinacular release. Overall, the rates of commonly recognized complications (stiffness, patellar fracture, and postoperative infection) were similar to those observed in smaller case series.

Patellofemoral instability in children: T2 relaxation times of the patellar cartilage in patients with and without patellofemoral instability and correlation with morphological grading of cartilage damage

BACKGROUND

Patellofemoral instability is one of the most common causes of cartilage damage in teenagers.

OBJECTIVE

To quantitatively evaluate the patellar cartilage in patients with patellofemoral instability using T2 relaxation time maps (T2 maps), compare the values to those in patients without patellofemoral instability and correlate them with morphological grades in patients with patellofemoral instability.

MATERIALS AND METHODS

Fifty-three patients with patellofemoral instability (mean age: 15.9 ± 2.4 years) and 53 age- and gender-matched patients without patellofemoral instability were included. Knee MR with axial T2 map was performed. Mean T2 relaxation times were obtained at the medial, central and lateral zones of the patellar cartilage and compared between the two groups. In the patellofemoral instability group, morphological grading of the patellar cartilage (0-4) was performed and correlated with T2 relaxation times.

RESULTS

Mean T2 relaxation times were significantly longer in the group with patellofemoral instability as compared to those of the control group across the patellar cartilage (Student's t-test, P<0.05) with the longest time at the central area. Positive correlation was seen between mean T2 relaxation time and morphological grading (Pearson correlation coefficiency, P<0.001). T2 increased with severity of morphological grading from 0 to 3 (mixed model, P<0.001), but no statistical difference was seen between grades 3 and 4.

CONCLUSION

In patellofemoral instability, patellar cartilage damage occurs across the entire cartilage with the highest T2 values at the apex. T2 relaxation times directly reflect the severity in low-grade cartilage damage, which implies an important role for T2 maps in differentiating between normal and low-grade cartilage damage.

Cartilage status in knees with recurrent patellar instability using magnetic resonance imaging T2 relaxation time value

PURPOSE

The purpose of the study was to analyse the patellar status in patients with recurrent patellar instability and in healthy controls using magnetic resonance imaging (MRI).

METHODS

One hundred and thirteen patients with patellar instability (patellar instability group) and 50 healthy controls (control group) were studied. All patients underwent computed tomography (CT) to measure the patellofemoral joint anatomy. Meanwhile, MRI was used to investigate cartilage status and to determine the T2 relaxation time value of the patellar cartilage plate. The mean values of these parameters for the patellar instability group and the control group were compared.

RESULTS

The CT images of the patellar instability group revealed greatly abnormal anatomy of the patellofemoral joint compared with the control group. By MRI assessment, 32 patients were determined to have a cartilage defect, which was confirmed under arthroscopy. Among the other 81 patients, the T2 relaxation time value of the patellar instability group was significantly higher than that of the control group on the middle (p = 0.032) or medial sites (p = 0.041) of the patellar cartilage.

CONCLUSIONS

The patellar instability group exhibits a higher risk of cartilage lesions with abnormal patellofemoral joint anatomy. MRI may enable early detection of these cartilage defects within the patellofemoral joint, enabling clinicians to adopt strategies to delay or prevent cartilage degeneration.

LEVEL OF EVIDENCE

III.

Pre- and postcontrast T1 and T2 mapping of patellar cartilage in young adults with recurrent patellar dislocation

PURPOSE

To examine the cartilage quality in young adults with recurrent patellar dislocation in childhood using different magnetic resonance imaging parameters.

METHODS

Sixteen young adults with unilateral recurrent patellar dislocation were investigated ≥5 y (mean, 8.5 y) after the first dislocation. Pre- and postcontrast T1 and precontrast T2 relaxation times were analyzed in four superficial and four deep patellar cartilage regions of both knees. Two hours after intravenous injection of 0.2 mM/kg Gd-DTPA(2-), postcontrast T1 [T1(Gd)] and ΔR1 [1/T1 (precontrast) - 1/T1 (postcontrast)] were analyzed in the regions. Muscle performance and patient-reported outcome were evaluated.

RESULTS

When comparing the injured side with the noninjured side, differences were seen in the superficial half but not the deep half of the cartilage. T1(Gd) was shorter in the central part, whereas T2 was shorter in the periphery of the patellar cartilage (P < 0.05). ΔR1 demonstrated similar differences between healthy and diseased cartilage as T1(Gd) alone. The knee function was not correlated to the degenerative changes.

CONCLUSION

The short T1(Gd) centrally indicates degenerative cartilage changes consistent with loss of glycosaminoglycans. Precontrast and ΔR1 calculations may be excluded in clinical dGEMRIC, which simplifies the procedure. A decrease in T2 may be a very early sign of joint pathology but warrants further investigation.

Long-term follow-up of nonoperatively and operatively treated acute primary patellar dislocation in skeletally immature patients

Purpose. The present study reports a long-term follow-up of acute primary patellar dislocation in patients with open physes. The purpose of the study was to evaluate knee function and recurrence rates after surgical and nonsurgical treatment of patellar dislocation. Methods. A total of 51 patients, including 29 girls and 22 boys, who were 9–14 years of age at the time of injury, were retrospectively evaluated. The minimum follow-up time was 5 years. Thigh muscle torque, range of motion, the squat test, the knee injury and osteoarthritis outcome score (KOOS), the Kujala score, and the recurrence rate were registered. Radiological predisposing factors at the time of injury were determined. Results. Quality of life and sports/recreation were the most affected subscales, according to KOOS, and a reduced Kujala score was also observed in all treatment groups. The surgically treated patients had a significantly lower recurrence rate. Those patients also exhibited reduced muscle performance, with a hamstring to quadriceps ratio (H/Q) of 1.03. The recurrence rate was not correlated with knee function. Conclusions. Patellar dislocation in children influences subjective knee function in the long term. Surgery appears to reduce the recurrence rate, but subjective knee function was not restored.

Clinical outcome after medial patellofemoral ligament reconstruction and autologous chondrocyte implantation following recurrent patella dislocation

PURPOSE

Medial patellofemoral ligament (MPFL) reconstruction is a well-established treatment option in recurrent patella dislocation. The combination with associated retropatellar cartilage lesions are severe injuries and very difficult to treat. The purpose of this study was to evaluate our clinical results of MPFL reconstruction and autologous chondrocyte implantation (ACI).

METHODS

Thirteen patients with recurrent patella dislocation were treated with a combination of MPFL reconstruction and ACI at our institution between 2010 and 2014. All patients had at least 2 patella dislocations. The posttraumatic cartilage lesions were grade IV according to the ICRS and were localized retropatellar in 8 cases and at the lateral femoral condyle in 2 cases. The mean defect size was 7.2±3.5 cm2 (3-12 cm2). Subjective and objective scores were assessed before surgery and at f/u, as well as radiologic parameters and cartilage status on magnetic resonance imaging (MRI).

RESULTS

Ten patients (5 male, 5 female) with a mean follow-up of 2 years (minimum 1 year to 4 years) were enrolled in the study. At latest clinical follow-up, all patients had a stable patella with no signs of instability and all patients showed improved subjective and objective scores. Lysholm score increased to 74.1±18.7 (48-99), KOOS score to 74.4±16.9 (57-95), IKDC subjective to 63.9±22.1 (34-93) and Kujala score to 73.8±25.1 (50-100). The post-operative modified MOCART score for quality assessment of the ACI on MRI was an average of 13.7±1.8 points (11-16), with a complete fill of the defect in 80% of lesions.

CONCLUSION

Medial patellofemoral ligament reconstruction with simultaneous ACI showed good clinical results in recurrent patella dislocation with traumatic cartilage lesions grade IV. No patella re-dislocation occurred and the ACI was successful in 80% of patients according to MRI. Subjective and objective scores improved but combined surgery is inferior to reports from the literature on MPFL reconstruction alone without cartilage damage.

LEVEL OF EVIDENCE

Therapeutic case series, Level IV.

A longitudinal study of the quantitative evaluation of patella cartilage after total knee replacement by delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) and T2 mapping at 3.0 T: preliminary results

OBJECTIVE

To characterize the quantitative changes of patella cartilage over time after total knee arthroplasty (TKA) by delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) and T2 mapping at 3.0 T.

METHOD

Twenty-six knees of 26 patients (23 women and three men, mean age, 75 years) with primary osteoarthritis and osteonecrosis of the knee underwent TKA with a zirconia ceramic implant in this prospective study. Twelve patients without patella resurfacing (NR group) and 14 patients with patella resurfacing (R group) had TKA with cemented fixation. The implant position was examined by radiograph, computed tomography (CT) and magnetic resonance imaging (MRI). The clinical scores were checked pre-operatively, 1 year post-operatively and at the final follow-up. Patella cartilage and its thickness were evaluated pre-operatively and 1 year after TKA by dGEMRIC and T2 mapping in the NR group only. Patella cartilage was divided into eight regions of interest: the deep and superficial layers of the outer lateral and medial half, and the inner lateral and medial half from the central ridge.

RESULTS

The implant position was appropriate in all cases and clinical scores were not significantly different between the two groups. The post-operative dGEMRIC value of the outer medial half superficial zone in the NR group was significantly decreased compared with the pre-operation value (P<0.05), whereas T2 mapping was not significantly changed in all zones. The cartilage thickness of the outer zone was significantly thinner post-operatively (P<0.05).

CONCLUSIONS

These findings indicate that osteoarthritic changes in the outer zone of patella cartilage occurred 1 year after TKA.

Arthroscopic, histological and MRI analyses of cartilage repair after a minimally invasive method of transplantation of allogeneic synovial mesenchymal stromal cells into cartilage defects in pigs

BACKGROUND AIMS

Transplantation of synovial mesenchymal stromal cells (MSCs) may induce repair of cartilage defects. We transplanted synovial MSCs into cartilage defects using a simple method and investigated its usefulness and repair process in a pig model.

METHODS

The chondrogenic potential of the porcine MSCs was compared in vitro. Cartilage defects were created in both knees of seven pigs, and divided into MSCs treated and non-treated control knees. Synovial MSCs were injected into the defect, and the knee was kept immobilized for 10 min before wound closure. To visualize the actual delivery and adhesion of the cells, fluorescence-labeled synovial MSCs from transgenic green fluorescent protein (GFP) pig were injected into the defect in a subgroup of two pigs. In these two animals, the wounds were closed before MSCs were injected and observed for 10 min under arthroscopic control. The defects were analyzed sequentially arthroscopically, histologically and by magnetic resonance imaging (MRI) for 3 months.

RESULTS

Synovial MSCs had a higher chondrogenic potential in vitro than the other MSCs examined. Arthroscopic observations showed adhesion of synovial MSCs and membrane formation on the cartilage defects before cartilage repair. Quantification analyses for arthroscopy, histology and MRI revealed a better outcome in the MSC-treated knees than in the non-treated control knees.

CONCLUSIONS

Leaving a synovial MSC suspension in cartilage defects for 10 min made it possible for cells to adhere in the defect in a porcine cartilage defect model. The cartilage defect was first covered with membrane, then the cartilage matrix emerged after transplantation of synovial MSCs.