Purpose
The primary outcome of interest of this study was to determine the frequency, location,
and extent of chondral injuries and medial patellofemoral ligament (MPFL) tears, along
with the rate of loose bodies, in the knee after acute primary patellar dislocation.
The secondary outcome of interest was to conduct a multivariate analysis to investigate
whether the presence of pathoanatomic abnormalities, including structural differences
in the knees of the patients, is associated with the features of the lesions.
Methods
Patients who underwent magnetic resonance imaging after primary acute patellar dislocation
were identified from our institutional databases. We analyzed a total of 175 magnetic
resonance imaging scans of patients aged between 14 and 25 years who were eligible
for inclusion.
Results
Chondral damage to the medial facet of the patella was present in 36 patients; patellar
crest, 78 patients; and lateral patellar facet, 28 patients. One patient presented
with chondral defects in the medial trochlear facet, whereas 118 patients showed chondral
defects in the lateral trochlear facet. Loose bodies were present in 142 patients.
A total of 161 patients (92%) showed MPFL damage. The patellar portion was affected
in 119 patients. Of the patients, 28 showed a partially damaged MPFL (<50%), 42 showed
MPFL damage greater than 50%, and 49 presented with a complete tear of the MPFL. MPFL
lesions were observed on the femoral side in 42 patients. Fourteen patients presented
with an avulsion fracture on the patellar side; 28 patients, on the femoral side.
Conclusions
The MPFL was injured in 92% of 175 patients after a first-time acute patellar dislocation.
Chondral damage was most frequent at the patellar crest, followed by the lateral femoral
epicondyle. No association was found between patella alta, the sulcus angle, the Q
angle, the tibial tubercle–trochlear groove distance, trochlear and patellar dysplasia,
and soft-tissue damage.
Level of Evidence
Level IV, retrospective cohort study.
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References
- High rate of recurrent patellar dislocation in skeletally immature patients: A long-term population-based study.Knee Surg Sports Traumatol Arthrosc. 2018; 26: 1037-1043
- Assessment of demographic and pathoanatomic risk factors in recurrent patellofemoral instability.Knee Surg Sports Traumatol Arthrosc. 2017; 25: 3849-3855
- Surgical management for recurrent patellar dislocations in skeletally immature patients.Eur J Orthop Surg Traumatol. 2019; 29: 1815-1822
- Chondral and soft tissue injuries associated to acute patellar dislocation: A systematic review.Life (Basel). 2021; 11: 1360
- 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.Pediatr Radiol. 2016; 46: 1134-1141
- Injury patterns of medial patellofemoral ligament and correlation analysis with articular cartilage lesions of the lateral femoral condyle after acute lateral patellar dislocation in children and adolescents: An MRI evaluation.Injury. 2015; 46: 1137-1144
- Acute traumatic patellar dislocation.Orthop Traumatol Surg Res. 2015; 101: S59-S67
- Autograft vs allograft comparison in pediatric medial patellofemoral ligament reconstruction.Ochsner J. 2019; 19: 96-101
- Single- versus double-bundle patellar graft insertion for isolated MPFL reconstruction in patients with patellofemoral instability: A systematic review of the literature.Arch Orthop Trauma Surg. 2020; 140: 769-776
- Prevalence of cartilage lesions and early osteoarthritis in patients with patellar dislocation.Eur Radiol. 2012; 22: 2347-2356
- [Arthroscopic treatment of acute patellar dislocation].Zhongguo Gu Shang. 2011; 24 ([in Chinese]): 729-731
- Primary traumatic patellar dislocation.J Orthop Surg Res. 2012; 7: 21
- Isolated arthroscopic lateral retinacular release for lateral patellar compression syndrome.Life (Basel). 2021; 11: 295
- Lateral retinacular release combined with MPFL reconstruction for patellofemoral instability: A systematic review.Arch Orthop Trauma Surg. 2021; 141: 283-292
- Roentgenographs and anatomic studies on the femoropatellar joint: With special reference to chondromalacia patellae.Acta Orthop Scand. 1941; 12: 319-410
- Factors of patellar instability: An anatomic radiographic study.Knee Surg Sports Traumatol Arthrosc. 1994; 2: 19-26
- Patella position in the normal knee joint.Radiology. 1971; 101: 101-104
- Classifications in brief: Outerbridge classification of chondral lesions.Clin Orthop Relat Res. 2018; 476: 2101-2104
- Extensions of interpolation between the arithmetic-geometric mean inequality for matrices.J Inequal Appl. 2017; 2017: 209
- Patellofemoral anatomy and biomechanics.Clin Sports Med. 2014; 33: 389-401
- Prevalence and site of medial patellofemoral ligament injuries in patients with acute lateral patellar dislocations: A systematic review and meta-analysis.Orthop J Sports Med. 2020; 8 (2325967120967338)
- MRI but not arthroscopy accurately diagnoses femoral MPFL injury in first-time patellar dislocations.Knee Surg Sports Traumatol Arthrosc. 2012; 20: 1575-1580
- Acute dislocation of the patella. A correlative pathoanatomic study.Am J Sports Med. 1996; 24: 52-60
- Arthroscopic surgery for primary traumatic patellar dislocation: A prospective, nonrandomized study comparing patients treated with and without acute arthroscopic stabilization with a median 7-year follow-up.Am J Sports Med. 2008; 36: 2301-2309
- Acute lateral patellar dislocation at MR imaging: Injury patterns of medial patellar soft-tissue restraints and osteochondral injuries of the inferomedial patella.Radiology. 2002; 225: 736-743
- Age-related differences in medial patellofemoral ligament injury patterns in traumatic patellar dislocation: Case series of 50 surgically treated children and adolescents.Am J Sports Med. 2012; 40: 2357-2364
- Medial patellofemoral ligament injury patterns and associated pathology in lateral patella dislocation: An MRI study.Sports Med Arthrosc Rehabil Ther Technol. 2009; 1: 17
- Magnetic resonance imaging of acute patellar dislocation in children: Patterns of injury and risk factors for recurrence.J Pediatr Orthop. 2012; 32: 145-155
- Cartilage lesions of the patella in recurrent patellar dislocation.Am J Sports Med. 2004; 32: 498-502
- MRI of traumatic patellar dislocation in children.Pediatr Radiol. 2006; 36: 1163-1170
- The relationship between trochlear dysplasia and medial patellofemoral ligament rupture location after patellar dislocation: An MRI evaluation.Knee. 2011; 18: 185-188
- Injury patterns of medial patellofemoral ligament after acute lateral patellar dislocation in children: Correlation analysis with anatomical variants and articular cartilage lesion of the patella.Eur Radiol. 2017; 27: 1322-1330
- Magnetic resonance imaging characteristics of the medial patellofemoral ligament lesion in acute lateral patellar dislocations considering trochlear dysplasia, patella alta, and tibial tuberosity-trochlear groove distance.Arthroscopy. 2010; 26: 926-935
- Gender-related differences in concomitant articular injuries after acute lateral patellar dislocation.Injury. 2021; 52: 1549-1555
- Comparison between surgical and nonsurgical treatment for primary patellar dislocations in adolescents: A systematic review and meta-analysis of comparative studies.Orthop J Sports Med. 2020; 8 (2325967120946446)
- Does surgical treatment produce better outcomes than conservative treatment for acute primary patellar dislocations? A meta-analysis of 10 randomized controlled trials.J Orthop Surg Res. 2020; 15: 118
- Fixation of traumatic chondral-only fragments of the knee in pediatric and adolescent athletes: A retrospective multicenter report.Orthop J Sports Med. 2018; 6 (2325967117753140)
- Surgical management of focal chondral defects of the knee: A Bayesian network meta-analysis.J Orthop Surg Res. 2021; 16: 543
- Management of patellar chondral defects with autologous matrix induced chondrogenesis (AMIC) compared to microfractures: A four years follow-up clinical trial.Life (Basel). 2021; 11: 141
- Clinical outcomes after the nonoperative management of lateral patellar dislocations: A systematic review.Orthop J Sports Med. 2018; 6 (2325967118766275)
- Conservative versus surgical treatment for repair of the medial patellofemoral ligament in acute dislocations of the patella.Arthroscopy. 2009; 25: 620-625
- Isolated repair of the medial patellofemoral ligament in primary dislocation of the patella: A prospective randomized study.Arthroscopy. 2008; 24: 881-887
- The operative management of patella malalignment.Open Orthop J. 2012; 6: 327-339
- Surgical versus conservative treatment for first patellofemoral dislocations: A meta-analysis of clinical trials.Eur J Orthop Surg Traumatol. 2020; 30: 771-780
Migliorini F, Eschweiler J, Betsch M, Knobe M, Tingart M, Maffulli N. Prognostic factors for isolated medial patellofemoral ligament reconstruction: A systematic review [published online May 4, 2021]. Surgeon. https://doi.org/10.1016/j.surge.2021.03.003.
- Isolated medial patellofemoral ligament reconstruction for recurrent patellofemoral instability: Analysis of outcomes and risk factors.J Orthop Surg Res. 2021; 16: 239
Migliorini F, Trivellas A, Eschweiler J, Knobe M, Tingart M, Maffulli N. Comparable outcome for autografts and allografts in primary medial patellofemoral ligament reconstruction for patellofemoral instability: Systematic review and meta-analysis [published online April 16, 2021]. Knee Surg Sports Traumatol Arthrosc. https://doi.org/10.1007/s00167-021-06569-w.
- Combined medial patellofemoral and medial patellotibial reconstruction for patellar instability: A PRISMA systematic review.J Orthop Surg Res. 2020; 15: 529
- Combined medial patellofemoral and patellotibial reconstruction with soft tissue fixation in recurrent patellar dislocation.Injury. 2020; 51: 1867-1873
- Traumatic patellar dislocation: Nonoperative treatment compared with MPFL reconstruction using patellar tendon.Am J Sports Med. 2012; 40: 114-122
- Pediatric mesenchymal stem cells exhibit immunomodulatory properties toward allogeneic T and B cells under inflammatory conditions.Front Bioeng Biotechnol. 2019; 7: 142
- New insights into osteogenic and chondrogenic differentiation of human bone marrow mesenchymal stem cells and their potential clinical applications for bone regeneration in pediatric orthopaedics.Stem Cells Int. 2013; 2013: 312501
- Current concepts on anatomy and biomechanics of patellar stability.Sports Med Arthrosc Rev. 2007; 15: 48-56
- The Elmslie-Trillat procedure: Evaluation in patellar dislocation and subluxation.Am J Sports Med. 1984; 12: 104-109
- Are the osseous and tendinous-cartilaginous tibial tuberosity-trochlear groove distances the same on CT and MRI?.Skeletal Radiol. 2015; 44: 1085-1093
- Systematic technique-dependent differences in CT versus MRI measurement of the tibial tubercle-trochlear groove distance.Am J Sports Med. 2015; 43: 675-682
- CT and MRI measurements of tibial tubercle-trochlear groove distances are not equivalent in patients with patellar instability.Am J Sports Med. 2013; 41: 1835-1840
- The difference between computed tomography and magnetic resonance imaging measurements of tibial tubercle-trochlear groove distance for patients with or without patellofemoral instability: A systematic review and meta-analysis.J Knee Surg. 2020; 33: 768-776
Article info
Publication history
Published online: February 11, 2022
Accepted:
January 30,
2022
Received:
October 8,
2021
Footnotes
The authors report no conflicts of interest in the authorship and publication of this article. Full ICMJE author disclosure forms are available for this article online, as supplementary material.
Identification
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© 2022 by the Arthroscopy Association of North America
