Abstract
Purpose
To use magnetic resonance imaging (MRI) scans to compare the prevalence of articular cartilage damage in patients with a single patellar dislocation versus those with multiple dislocations and to compare the locations and severity of chondral injury between the groups.
Methods
Patients with patellar dislocation between January 2017 and July 2021 were retrospectively identified. Patients with a documented history of patellar dislocation and an MRI scan of the affected knee were included. Patients with articular cartilage injury prior to the dislocation event were excluded. Articular cartilage injury was graded using a validated system: AMADEUS (Mean Total Area Measurement and Depth & Underlying Structures). Caton-Deschamps Index (CDI) scores and Dejour classifications of trochlear dysplasia were also collected. Data were calculated by performing t tests, Mann-Whitney tests, and χ2 or Fisher Exact tests to calculate P values for categorical data.
Results
In total, 233 patients were included: 117 with primary dislocations and 116 with recurrent dislocations. Articular cartilage injuries were present in 51 patients with primary dislocations (43.6%) and 68 patients with recurrent dislocations (58.6%, P = .026). On comparison of the groups, the recurrent group contained a significantly larger proportion of female patients (65.5% vs 46.2%, P = .004). There was no difference in lesion size, subchondral bone defect, presence of bone edema, or total AMADEUS score between groups (P = .231). Caton-Deschamps Index scores were not significant when comparing between groups; however, the Dejour classifications showed higher grades in the recurrent group (P = .013 for A-D grading scale and P = .005 for high/low grading scale). Subgroup analysis revealed that when cartilage damage was present, patients from the primary group had significantly more full-thickness lesions (P < .001) and lower AMADEUS scores (P = .016).
Conclusions
There was a similarly high prevalence of cartilage injury seen on MRI after both a primary patellar dislocation and a recurrent patellar dislocation. Chondral injury primarily affected the medial and lateral patellar facets and the lateral femoral condyle in both the primary and recurrent dislocation groups. However, the primary group showed an increased number of full-thickness lesions. There was no difference in lesion size, subchondral bone defect, presence of bone edema, or total AMADEUS score between the primary and recurrent groups.
Level of Evidence
Level III, retrospective comparative prognostic investigation.
The prevalence of patellar instability is common, affecting 14 of 100,000 persons.1 Given that stability of the patellofemoral joint depends on both bony and soft-tissue structures, the presence of patellar instability has been attributed to several risk factors such as younger age, patella alta, trochlear dysplasia, valgus malalignment, increased tibial tubercle–trochlear groove distance, and rotational malalignment.2,3 Although surgical treatment is typically reserved for patients with recurrent instability, the recurrence rate after first-time dislocation when treated conservatively has been found to be 33.6%4 whereas historical references report rates of 15% to 44%.5,6 This may increase the risk of further articular cartilage injury because the frequency of chondral or osteochondral lesion development after lateral patellar dislocation has been reported to be between 43% and 70%.1,7,8
Franzone et al.9 investigated the relation between recurrent patellar instability and articular cartilage damage in a cohort of patients undergoing medial patellofemoral ligament reconstruction (MPFLR) and found that 24 of 38 patients (63.2%) had a patellofemoral cartilage lesion. Furthermore, patients with chronic instability (>5 years) were found to have an increased prevalence of trochlear cartilage lesions.9 A similar study by von Engelhardt et al.10 analyzed both magnetic resonance imaging (MRI) and arthroscopic findings in a mixed cohort of first-time and recurrent dislocation patients. During arthroscopic assessment, all but 3 patients were found to have some degree of cartilage damage (92%). Moreover, a systematic review and meta-analysis by Xará-Leite et al.11 found MRI to be clinically reliable in detecting articular cartilage damage after patellar dislocation.
Good to excellent outcomes after patellar instability surgery for both bony realignment and soft-tissue ligament reconstruction procedures are well documented within the literature.12, 13, 14 However, the incidence of articular cartilage disease after initial and recurrent patellar dislocation remains poorly understood, and there is a paucity of literature comparing the extent of cartilage damage between first-time and recurrent dislocations.1,7,15, 16, 17, 18, 19, 20, 21
The purposes of this study were to use MRI studies to compare the prevalence of articular cartilage damage in patients with a single patellar dislocation versus those with multiple dislocations and to compare the locations and severity of chondral injury between the groups. We hypothesized that patients with recurrent patellar instability would have an increased prevalence of cartilage lesions, the locations of chondral injury would be similar between the groups, and the severity of cartilage lesions would be greater in the recurrent dislocation group.
Methods
Patient Selection
The STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) guidelines were used when designing and reporting this study, which was approved by our institutional review board (Jefferson Institutional Review Board No. 19D.418). Patients in whom an episode of patellar dislocation was diagnosed between January 2017 and July 2021 were retrospectively identified using International Classification of Diseases, Ninth Revision code 836.3, as well as International Classification of Diseases, Tenth Revision codes S83.005A and S83.004A. Patients were included if chart review confirmed a history of patellar dislocation and an MRI scan of the affected knee was available for analysis. Patients with a documented history of multiple dislocations were only included if an MRI scan was available after a recurrent dislocation. MRI scans needed to have a minimum field strength of 1.5 T to be eligible for inclusion. Individuals with a history of cartilage surgery (chondroplasty, microfracture, autologous chondrocyte implantation, osteochondral allograft or autograft procedure, arthroscopic loose body removal, or chondral and osteochondral fragment fixation) prior to their first dislocation were excluded (Fig 1).
Fig 1.
CONSORT (Consolidated Standards of Reporting Trials) diagram showing number of patients excluded at each time point in study before final inclusion. (MRI, magnetic resonance imaging.)
Data Extraction
Medical records were analyzed to determine whether patients had experienced a single patellar dislocation or multiple patellar dislocations at the time of review. Demographic variables such as age, sex, body mass index, race, and laterality were recorded. Caton-Deschamps Index (CDI) scores were collected and analyzed for both primary dislocations and recurrent dislocations (Appendix Table 1).22 Dejour classifications of trochlear dysplasia were collected using the A-to-D grading system as well as the high/low system (Appendix Table 2).23 Post-dislocation MRI scans were analyzed by 3 independent reviewers, all of whom are fellowship-trained orthopaedic surgeons (M.C., M.C.C., and a non-author), using the validated AMADEUS (Mean Total Area Measurement and Depth & Underlying Structures) system as described by Jungmann et al.24 This MRI-based system classifies focal cartilage lesions by taking into account defect size (area), depth, subchondral bone involvement, and defect-associated bone marrow edema.24 The scale is scored from 0 to 100, with a score of 100 indicating no cartilage lesion. In patients with multiple cartilage defects on MRI, each defect was characterized and analyzed independently. The full cohorts of first-time and recurrent dislocation patients were compared. Patient names, as well as initials, and whether the patient experienced an initial or recurrent dislocation were blinded to ensure a non-bias review. Additional subanalysis was performed to isolate and directly compare only the patients with cartilage lesions.
Statistical Analysis
Agreement testing was performed using the Fleiss κ as an index of inter-rater agreement on categorical data. The Fleiss grading system was used to determine whether agreement was satisfactory among reviewers.25 An interclass correlation coefficient was used for agreement testing on quantitative data. Parametric continuous data are presented as mean values, and P values were calculated by performing unpaired t tests. Nonparametric continuous data are also presented as mean values for easier interpretation and were calculated by performing Mann-Whitney tests. Categorical data are presented as cell count (percentage). Fisher exact tests were used to calculate P values for categorical data. P < .05 was deemed significant. All statistical analyses were performed using RStudio software (version 3.6.3; Vienna, Austria).
Results
In total, 721 patients were eligible for study inclusion. Of these patients, 488 did not have MRI scans after their patellar dislocation episodes (initial or recurrent) or had a known history of articular cartilage damage before their initial patellar dislocation. This left 233 patients for analysis. Of these, 117 had primary dislocations and 116 had multiple dislocations at the time of MRI. There were significantly more female patients in the recurrent group (65.50% vs 46.20%, P = .004). The mean age of female patients was 24.3 years, and that of male patients was 24.6 years. However, between groups, there was no difference in age at MRI, body mass index, race, laterality of lesion, or presence of lesion (Table 1). Cartilage lesions were present in 58.60% of the recurrent instability patients and 43.55% of the first-time dislocation patients (P = .026). Multifocal lesions were found in 10 patients in the primary group (8.55%) and 15 patients in the recurrent group (12.90%, P = .298).
Table 1.
Demographic Characteristics of Cohorts
| Primary (n = 117) | Recurrent (n = 116) | P Value | |
|---|---|---|---|
| Age at MRI, mean (SD), yr | 24.4 (11.9) | 23.0 (9.55) | .943 |
| Sex | .004∗ | ||
| Female | 54 (46.2) | 76 (65.5) | |
| Male | 63 (53.8) | 40 (34.5) | |
| BMI, mean (SD) | 25.2 (5.38) | 25.5 (6.16) | .94 |
| Race | .518 | ||
| Unknown | 16 (13.7) | 17 (14.7) | |
| White | 89 (76.1) | 88 (75.9) | |
| Black | 8 (6.84) | 8 (6.90) | |
| Multiple | 4 (3.42) | 3 (2.58) | |
| Laterality | >.999 | ||
| Left | 61 (52.1) | 61 (52.6) | |
| Right | 56 (47.9) | 55 (47.4) |
NOTE. Data are presented as number of patients (percentage) unless otherwise indicated. Categorical values were analyzed using the Fisher exact test, whereas numerical values were calculated using t tests.
BMI, body mass index; MRI, magnetic resonance imaging; SD, standard deviation.
Statistically significant (P < .05).
There was a higher proportion of patients in the primary group with a full-thickness lesion compared with the recurrent group (82.0% vs 41.0%, P < .001). There was significant variation in the distribution of lesion locations between the groups. However, there was no difference in mean lesion area, subchondral bone edema, subchondral bone defect, or total AMADEUS score (Table 2). Subgroup analysis was performed to isolate patients with lesions and exclude patients with no lesions. Patients with cartilage lesions in the primary dislocation group had significantly lower AMADEUS scores than those with cartilage lesions in the recurrent group (64.8 ± 9.15 vs 67.5 ± 12.8, P = .016). Both Dejour classification systems of trochlear dysplasia were significant when comparing primary and recurrent dislocations, with higher grades of dysplasia noted in the recurrent dislocation group for both the A-to-D grading scale and the high/low grading scale (P = .013 and P = .005, respectively) (Table 3). CDI scores were not significantly different between primary and recurrent dislocations (P = .275).
Table 2.
Lesion Characteristics
| Primary (n = 127) | Recurrent (n = 131) | P Value | |
|---|---|---|---|
| Presence of lesion | .026 | ||
| No lesion | 66 (56.4) | 48 (41.4) | |
| Single lesion | 41 (35.0) | 53 (45.7) | |
| Multiple lesions | 10 (8.55) | 15 (12.9) | |
| Lesion area, mean (range), cm2 | 1.14 (0.04-3.61) | 1.13 (0.2-4) | .454 |
| Lesion edema | >.999 | ||
| No | 22 (36.1) | 30 (36.1) | |
| Yes | 39 (63.9) | 53 (63.9) | |
| Lesion location | .026∗ | ||
| Medial femoral condyle | 0 (0.0) | 6 (7.2) | |
| Lateral femoral condyle | 12 (19.7) | 12 (14.5) | |
| Patellar lateral facet | 18 (29.5) | 28 (33.7) | |
| Patellar medial facet | 25 (41.0) | 25 (30.1) | |
| Patellar inferior pole | 0 (0.0) | 4 (4.8) | |
| Patellar superior pole | 0 (0.0) | 1 (1.2) | |
| Trochlear central groove | 1 (1.6) | 2 (2.4) | |
| Medial trochlea | 1 (1.6) | 0 (0.0) | |
| Lateral trochlea | 1 (1.6) | 5 (6.0) | |
| Lateral tibial plateau | 3 (4.2) | 0 (0.0) | |
| Grade of articular cartilage injury | <.001∗ | ||
| Signal alteration | 1 (1.6) | 17 (20.5) | |
| Partial | 10 (16.4) | 32 (38.6) | |
| Full | 50 (82.0) | 34 (41.0) | |
| Subchondral bone defect | .438 | ||
| None | 38 (62.3) | 56 (67.5) | |
| <5 mm | 23 (37.7) | 25 (30.1) | |
| >5 mm | 0 (0) | 2 (2.4) | |
| AMADEUS score for lesions, mean (SD) | 64.8 (9.15) | 67.5 (12.8) | .016∗ |
| Total AMADEUS score, mean (range) | 83.1 (50-100) | 79.4 (20-100) | .231 |
NOTE. Data are presented number of lesions (percentage) unless otherwise indicated. Categorical values were analyzed using the Fisher exact test, whereas numerical values were calculated using t tests.
AMADEUS, Mean Total Area Measurement and Depth & Underlying Structures; SD, standard deviation.
Statistically significant (P < .05).
Table 3.
Dejour Classifications and Caton-Deschamps Index Measurements
| Primary (n = 117) | Recurrent (n = 116) | P Value | |
|---|---|---|---|
| Caton-Deschamps Index, mean (SD) | .588 | ||
| A, mm | 41.4 (7.5) | 41.9 (7.5) | |
| B, mm | 34.7 (3.9) | 34.4 (3.9) | |
| A/B ratio | 1.2 (0.2) | 1.2 (0.2) | |
| Dejour A-D classification | .021∗ | ||
| None | 0 (0.0) | 1 (0.9) | |
| A | 71 (60.7) | 51 (44.0) | |
| B | 3 (2.6) | 8 (6.9) | |
| C | 41 (35.0) | 46 (39.7) | |
| D | 2 (1.7) | 10 (8.6) | |
| Dejour low/high classification | .023∗ | ||
| None | 0 (0.0) | 1 (1.6) | |
| Low | 71 (60.7) | 51 (44.0) | |
| High | 46 (39.3) | 64 (55.2) |
NOTE. Data are presented number of lesions (percentage) unless otherwise indicated. Categorical values were analyzed using the Fisher exact test, whereas numerical values were calculated using t tests.
SD, standard deviation.
Statistically significant (P < .05).
Interobserver Reliability
Overall, interobserver reliability was strong (Table 4). Regarding categorical variables, the κ statistics were 1.0 for presence of articular cartilage injury (very strong agreement), 0.545 for grade of injury (moderate/strong agreement), 0.815 for location of lesion (strong agreement), 0.488 for subchondral bone involvement (moderate agreement), and 0.622 for presence of bone edema (strong agreement). The interclass correlation coefficient score for quantitative size of articular cartilage defect measurements was 0.791, indicating strong agreement.
Table 4.
Interobserver Reliability
| Variable of Interest | Statistic | Agreement Interpretation |
|---|---|---|
| Categorical data | ||
| Presence of articular cartilage injury | κ = 1 | Very strong agreement (full) |
| Grade of injury | κ = 0.545 | Moderate/strong agreement |
| Location | κ = 0.815 | Strong agreement |
| Subchondral bone defect | κ = 0.488 | Moderate agreement |
| Bone edema | κ = 0.622 | Strong agreement |
| Quantitative data | ||
| Size of articular cartilage defect | ICC = 0.791 | Strong agreement |
ICC, interclass correlation coefficient.
Discussion
We found that recurrent dislocators had a higher frequency of cartilage injury than primary dislocators (58.6% vs 43.55%, P = .026), as well as a greater prevalence of injury to the lateral patellar facet, and in fact had less severe lesion injury than first-time dislocators (AMADEUS score, 64.8 ± 9.15 vs 67.5 ± 12.8; P = .016). Articular cartilage injury in patients with recurrent dislocations and first-time dislocators was common. The recurrent instability group was found to have an increased frequency of multifocal lesions when compared with the primary instability group (12.9% vs 8.55%), although this was not significant (P = .298). Location of chondral injury was found to be significantly different between recurrent dislocators and primary dislocators (P = .026). Lesions primarily affected the patellar medial and lateral facets, followed by the lateral femoral condyle.
Regarding the prevalence of articular cartilage injury between first-time and recurrent dislocators, there was a greater prevalence of injury in the recurrent instability group. In a longitudinal MRI study looking at imaging of patellar stabilization patients after their initial dislocation, as well as additional imaging after recurrent dislocations prior to surgery, Hadley et al.7 found that the incidence of articular cartilage injury after an initial dislocation was 45.7%. After a second dislocation, the incidence of articular cartilage injury increased to 62.9%, a statistically significant increase of 17.2% (P = .031).7
The CDI measures patellar height to determine patella alta and patella baja.4 Our study found no significant difference in CDI scores between the primary and recurrent instability groups (P = .275). However, both the A-to-D and high/low Dejour classifications of trochlear dysplasia showed significantly higher grades in the recurrent instability group (P = .013 and P = .005, respectively). The CDI has been shown to predict outcomes in patients undergoing MPFLR and increased patellar instability after surgery.22 Similarly, trochlear dysplasia has been seen to significantly affect outcomes after stabilization for patellar instability.26 It is interesting to note that a recent systematic review found that patella alta did not adversely affect outcomes after isolated MPFLR whereas mixed data were found regarding trochlear dysplasia and outcomes.27
The greater prevalence of lateral patellar facet lesions in the recurrent dislocation group is interesting, and this finding could be related to the biomechanical state of the knee with recurrent instability. A systematic review by Migliorini et al.16 reported that a majority of chondral lesions were found in the medial patellar facet. There may be increased lateral patellar maltracking in a knee with a deficient medial patellofemoral ligament or chronic malalignment, leading to the increased presence of lateral patellar facet lesions.
Surprisingly, greater severity of cartilage injury was observed in the primary dislocation group compared with the recurrent instability group (AMADEUS score, 64.8 ± 9.15 vs 67.5 ± 12.8; P = .016). This finding is difficult to explain. One possibility is that differences in demographic characteristics between our groups contributed to this finding, with male patients versus female patients comprising 46% versus 54% of the primary group and 66% versus 35% of the recurrent group. There may be sex-related differences contributing to the difference in lesion depth, but this has yet to be proved in the literature. Another possible explanation is that chondral lesions sustained by first-time dislocators experience healing over time. Therefore, when patients with recurrent dislocations undergo imaging after multiple dislocations, the lesions appear less severe. However, the current body of evidence suggests that damaged cartilage has a limited ability to heal naturally.28 A third possible explanation is that patients who sustain multiple dislocations may have a component of ligamentous laxity that offers some protection from sustaining more severe chondral injury during dislocation. Finally, selection bias may have played a role in the increased frequency of severe injury in primary dislocators. If an individual has a more traumatic patellar dislocation, the concern for articular cartilage damage perhaps is greater and MRI is more urgent. These individuals were more likely to have undergone stabilization surgery after their initial dislocation, restricting them from being part of the recurrent instability group. Although the standard of care for first-time patellar dislocation is to obtain an MRI scan, recurrent dislocators may have not received an MRI scan initially and the question now becomes, Was the MRI scan conducted for articular cartilage damage concerns or preoperative imaging to guide surgery?29 Further study is warranted to determine the biomechanics of cartilage injury between the intact and deficient medial patellofemoral ligament state, as well as between male and female patients.
Limitations
There are limitations to this study. It is retrospective in nature. There were demographic differences between the 2 groups. We do not have patient-reported outcomes to correlate whether the observed differences in cartilage severity correlate with symptoms. Our study did not have a power analysis conducted before the commencement of the project, allowing the possibility of a type II error within out study. Our study could have benefited from the matching of cohorts to avoid the demographic differences seen in sex between our first-time and recurrent dislocators. Time between dislocation and MRI was not analyzed, allowing patellar lesions to possibly arise owing to consistent patellar maltracking rather than the dislocation itself. Furthermore, MRI quality may differ between patients because the MRI scans were not performed at the same facility and may have been performed with varying field strengths and machine types. This could have been supplemented with intraoperative data collection. The overall sensitivity and specificity of MRI compared with other forms of diagnosis such as arthroscopy are also inherent limitations of MRI.30 However, any MRI scan that did not meet our criteria for analysis was excluded.
Conclusions
There was a similarly high prevalence of cartilage injury seen on MRI after both a primary patellar dislocation and a recurrent patellar dislocation. Chondral injury primarily affected the medial and lateral patellar facets and the lateral femoral condyle in both the primary and recurrent dislocation groups. However, the primary group showed an increased number of full-thickness lesions. There was no difference in lesion size, subchondral bone defect, presence of bone edema, or total AMADEUS score between the primary and recurrent groups.
Disclosures
The authors report the following potential conflicts of interest or sources of funding: F.P.T. receives consulting fees from Medical Device Business Services; is a board member of American Academy of Orthopaedic Surgeons and American Orthopaedic Society for Sports Medicine; and owns stock or stock options in Trice Medical. S.B.C. receives grants or contracts from Arthrex and Slack; receives consulting fees from ConMed and Zimmer; receives payment or honoraria from Zimmer; is a board member of American Orthopaedic Society for Sports Medicine and International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine; and reports other nonfinancial interests in Slack. K.B.F. receives consulting fees from DePuy (A Johnson & Johnson Company), Vericel, and Medical Device Business Services; receives support for attending meetings and/or travel from Liberty Surgical; and is a board member of American Orthopaedic Society for Sports Medicine. All other authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this article. Full ICMJE author disclosure forms are available for this article online, as supplementary material.
Supplementary Data
References
- 1.Isacsson A., Olsson O., Englund M., Frobell R.B. Incidence and concomitant chondral injuries in a consecutive cohort of primary traumatic patellar dislocations examined with sub-acute MRI. Int Orthop. 2023;47:973–981. doi: 10.1007/s00264-023-05707-y. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Diederichs G., Issever A.S., Scheffler S. MR imaging of patellar instability: Injury patterns and assessment of risk factors. Radiographics. 2010;30:961–981. doi: 10.1148/rg.304095755. [DOI] [PubMed] [Google Scholar]
- 3.Dejour D., Le Coultre B. Osteotomies in patello-femoral instabilities. Sports Med Arthrosc Rev. 2018;26:8–15. doi: 10.1097/JSA.0000000000000183. [DOI] [PubMed] [Google Scholar]
- 4.Huntington L.S., Webster K.E., Devitt B.M., Scanlon J.P., Feller J.A. Factors associated with an increased risk of recurrence after a first-time patellar dislocation: A systematic review and meta-analysis. Am J Sports Med. 2020;48:2552–2562. doi: 10.1177/0363546519888467. [DOI] [PubMed] [Google Scholar]
- 5.Fithian D.C., Paxton E.W., Stone M.L., et al. Epidemiology and natural history of acute patellar dislocation. Am J Sports Med. 2004;32:1114–1121. doi: 10.1177/0363546503260788. [DOI] [PubMed] [Google Scholar]
- 6.Hawkins R.J., Bell R.H., Anisette G. Acute patellar dislocations. The natural history. Am J Sports Med. 1986;14:117–120. doi: 10.1177/036354658601400204. [DOI] [PubMed] [Google Scholar]
- 7.Hadley C.J., Rao S., Ajami G., et al. Articular cartilage damage worsens from first-time to recurrent patellar dislocation—A longitudinal magnetic resonance imaging study. Arthrosc Sports Med Rehabil. 2022;4:e343–e347. doi: 10.1016/j.asmr.2021.10.006. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8.Salonen E.E., Mäenpää H., Mattila V.M., Magga T., Kiekara T., Sillanpää P.J. Traumatic patellar dislocation and cartilage injury: A follow-up study of long-term cartilage deterioration. Am J Sports Med. 2017;45:1376–1382. doi: 10.1177/0363546516687549. [DOI] [PubMed] [Google Scholar]
- 9.Franzone J.M., Vitale M.A., Shubin Stein B.E., Ahmad C.S. Is there an association between chronicity of patellar instability and patellofemoral cartilage lesions? An arthroscopic assessment of chondral injury. J Knee Surg. 2012;25:411–416. doi: 10.1055/s-0032-1313747. [DOI] [PubMed] [Google Scholar]
- 10.von Engelhardt L.V., Raddatz M., Bouillon B., et al. How reliable is MRI in diagnosing cartilaginous lesions in patients with first and recurrent lateral patellar dislocations? BMC Musculoskelet Disord. 2010;11:149. doi: 10.1186/1471-2474-11-149. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Xará-Leite F., Vinha A., Valente C., Andrade R., Espregueira-Mendes J. Magnetic resonance imaging is able to detect patellofemoral focal cartilage injuries: A systematic review with meta-analysis. Knee Surg Sports Traumatol Arthrosc. 2023;31:2469–2481. doi: 10.1007/s00167-022-07203-z. [DOI] [PubMed] [Google Scholar]
- 12.Cohen D., Le N., Zakharia A., Blackman B., de Sa D. MPFL reconstruction results in lower redislocation rates and higher functional outcomes than rehabilitation: A systematic review and meta-analysis. Knee Surg Sports Traumatol Arthrosc. 2022;30:3784–3795. doi: 10.1007/s00167-022-07003-5. [DOI] [PubMed] [Google Scholar]
- 13.Schneider D.K., Grawe B., Magnussen R.A., et al. Outcomes after isolated medial patellofemoral ligament reconstruction for the treatment of recurrent lateral patellar dislocations: A systematic review and meta-analysis. Am J Sports Med. 2016;44:2993–3005. doi: 10.1177/0363546515624673. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 14.Xu T., Zhu Y., Zhang L., Xie H.Q., Fu W. Results of medial patellofemoral ligament reconstruction with and without tibial tubercle transfer in patellar instability: A systematic review and meta-analysis. Orthop Surg. 2023;15:2766–2776. doi: 10.1111/os.13870. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 15.Migliorini F., Marsilio E., Cuozzo F., et al. Chondral and soft tissue injuries associated to acute patellar dislocation: A systematic review. Life (Basel) 2021;11:1360. doi: 10.3390/life11121360. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Migliorini F., Marsilio E., Oliva F., Eschweiler J., Hildebrand F., Maffulli N. Chondral injuries in patients with recurrent patellar dislocation: A systematic review. J Orthop Surg Res. 2022;17:63. doi: 10.1186/s13018-022-02911-1. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17.Chen X., Li D., Wang W., Xin H., Wang Y., Wang J. Cartilage status in knees with recurrent patellar instability using magnetic resonance imaging T2 relaxation time value. Knee Surg Sports Traumatol Arthrosc. 2015;23:2292–2296. doi: 10.1007/s00167-014-3036-z. [DOI] [PubMed] [Google Scholar]
- 18.Luhmann S.J., Smith J.C., Schootman M., Prasad N. Recurrent patellar instability: Implications of preoperative patellar crepitation on the status of the patellofemoral articular cartilage. J Pediatr Orthop. 2019;39:33–37. doi: 10.1097/BPO.0000000000001017. [DOI] [PubMed] [Google Scholar]
- 19.Uimonen M., Ponkilainen V., Paloneva J., Mattila V.M., Nurmi H., Repo J.P. Characteristics of osteochondral fractures caused by patellar dislocation. Orthop J Sports Med. 2021;9 doi: 10.1177/2325967120974649. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 20.Vollnberg B., Koehlitz T., Jung T., et al. Prevalence of cartilage lesions and early osteoarthritis in patients with patellar dislocation. Eur Radiol. 2012;22:2347–2356. doi: 10.1007/s00330-012-2493-3. [DOI] [PubMed] [Google Scholar]
- 21.Gonzalez R.C., Ryskamp D.J., Swinehart S.D., et al. Patellofemoral articular cartilage damage is associated with poorer patient-reported outcomes following isolated medial patellofemoral ligament reconstruction. Knee Surg Sports Traumatol Arthrosc. 2023;31:2794–2801. doi: 10.1007/s00167-022-07221-x. [DOI] [PubMed] [Google Scholar]
- 22.Brutico J., Paul R.W., Wright M., et al. Preoperative patella alta on Caton-Deschamps index is a predictor of outcome following isolated medial patellofemoral ligament reconstruction. Arthrosc Sports Med Rehabil. 2023;5:e523–e528. doi: 10.1016/j.asmr.2023.02.006. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 23.Fuchs A., Feucht M.J., Dickschas J., et al. Interobserver reliability is higher for assessments with 3D software-generated models than with conventional MRI images in the classification of trochlear dysplasia. Knee Surg Sports Traumatol Arthrosc. 2022;30:1654–1660. doi: 10.1007/s00167-021-06697-3. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 24.Jungmann P.M., Welsch G.H., Brittberg M., et al. Magnetic Resonance Imaging Score and Classification System (AMADEUS) for assessment of preoperative cartilage defect severity. Cartilage. 2017;8:272–282. doi: 10.1177/1947603516665444. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 25.Laerd Statistics Fleiss’ kappa in SPSS Statistics. https://statistics.laerd.com/spss-tutorials/fleiss-kappa-in-spss-statistics.php
- 26.Hiemstra L.A., Kerslake S., Loewen M., Lafave M. Effect of trochlear dysplasia on outcomes after isolated soft tissue stabilization for patellar instability. Am J Sports Med. 2016;44:1515–1523. doi: 10.1177/0363546516635626. [DOI] [PubMed] [Google Scholar]
- 27.Pappa N., Good L., DiBartola A., Martin K., Flanigan D.C., Magnussen R.A. Patella alta and increased TT-TG distance do not adversely affect patient-reported outcomes following isolated MPFL reconstruction: A systematic review. J ISAKOS. 2023;8:352–363. doi: 10.1016/j.jisako.2023.08.001. [DOI] [PubMed] [Google Scholar]
- 28.Lee D.H., Kim S.J., Kim S.A., Ju G-i. Past, present, and future of cartilage restoration: From localized defect to arthritis. Knee Surg Relat Res. 2022;34:1. doi: 10.1186/s43019-022-00132-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 29.Xu Z., Zhang H., Yan W., Chen J., Zhou A. How to evaluate and treat skeletally mature patients with patellar dislocation. Arthrosc Tech. 2021;10:e721–e726. doi: 10.1016/j.eats.2020.10.064. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 30.Baker H., Dickherber J., Reddy M., Rizzi A., Kahn A., Athiviraham A. Diagnostic value of MRI and radiographs of the knee to identify osteochondral lesions in acute patellar instability. J Knee Surg. 2022;35:1604–1609. doi: 10.1055/s-0041-1729551. [DOI] [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.