Medial patellofemoral ligament tears in the setting of multiligament knee injuries rarely cause patellar instability

A third of patients with multiligament knee injuries exhibit radiological signs of patella dislocation

Purpose

Multiligament knee injury (MLKI) is considered major trauma. What is currently undescribed is the incidence of concomitant patella dislocation in a setting of MLKI, which is needed for a better understanding of concomitant injuries that are a consequence of the dislocated patella - rupture of the medial patellofemoral ligament (MPFL) and cartilage lesions. The present study aimed to investigate the incidence of patellar dislocation in the MLKI setting.

Methods

Magnetic resonance imaging (MRI) and operative note review of two major trauma centres for 2016-2023 were performed. MLKIs, defined as a disruption of at least two major knee ligaments, are classified as either ACL- or PCL-based or cruciate. All cases had a preoperative MRI and were treated surgically. Patella dislocation on MRI was defined as: (1) dislocated patella, (2) lateralization >2/3 with a bone bruise/cartilage injury, (3) bony or intrasubstance MPFL rupture with or without a bone bruise/cartilage injury. Note was also made on whether the patella was displaceable during surgery. The incidence of MPFL reconstructions was noted via the operative notes.

Results

A total of 364 MKLIs were included. Mean age was 36.0 ± 13.4 years, 131 patients were female (36.0%). Observed incidence of patella instability was 29.7%: disruption of the MPFL was 75 cases (20.6%), lateralization of the patella in combination with bone bruise/cartilage injury in 30 cases (8.2%) as well as one case of a dislocated patella on MRI (0.27%). MPFL reconstruction was performed in 14 cases, and in 2 cases, a repair was performed (4.4%).

Conclusion

The present study demonstrates that the incidence of patella dislocation in the setting of MLKI can be as high as 29.1%. The clinical relevance of currently diagnosing and managing patellar dislocation in the setting of MLKI requires further research.

Level of Evidence

Level III, retrospective study.

Greater Detail Is Needed When Reporting Schenck Knee Dislocation V Injuries in the Orthopaedic Literature: A Systematic Review

Purpose

To examine how knee dislocations (KDs) with associated periarticular fractures classified using the Schenck KD V subcategory are reported in the literature.

Methods

PubMed, Cumulative Index to Nursing and Allied Health Literature, and Scopus were queried in January 2024. Studies were included if full-text articles in English were available, the Schenck KD classification system was used, and Schenck KD class V was mentioned. The exclusion criteria were as follows: studies in which the Schenck KD classification system was used but only KD classes I to IV were mentioned; systematic reviews, meta-analyses, review articles, commentaries, surgical technique articles, or animal studies; or studies in which pediatric patients were included. Studies were systematically examined for details regarding the descriptions of KD V injuries, including fracture and ligament tear patterns.

Results

Seventy-four studies met the inclusion criteria. Of these 74 studies, 45 (60.8%) provided no description of either the ligament tear or fracture patterns that were present in KD V injuries. Fifty-two studies (70.3%) provided no description of the ligament tear patterns and 51 studies (68.9%) provided no description of the fracture patterns associated with KD V injuries. Only 16 of 74 studies (21.6%) included descriptions of ligament tear patterns and fractures present in KD V injuries.

Conclusions

Descriptions of Schenck KD class V are poorly represented in the orthopaedic literature.

Level of Evidence

Level IV, systematic review of Level II to IV studies.

Knee dislocation with concomitant patellofemoral dislocation: A systematic review

Background

There is no consensus treatment for knee dislocations with associated patellar dislocation. This systematic review provides an overview of current treatments and the authors preferred treatment algorithm. Knee dislocation with concomitant patellar dislocation is a rare occurrence and there is no standard of care for these injuries. This review seeks to provide a systematic review of literature and a proposed treatment algorithm for this injury pattern.

Methods

A systematic review was performed following PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) guidelines using the PubMed, MEDLINE, and Cochrane databases in July 2024. Studies were assessed for human patients who sustained a knee dislocation with concomitant patellar dislocation.

Results

The literature search yielded 288 titles and abstracts to be screened. Of the 288 articles, 281 titles and abstracts were excluded. Ultimately six full text articles were included. There were three case reports/series of acute knee dislocation with associated patellar dislocation and there were three case reports of chronic knee dislocation with associated patellar dislocation. In all studies, patellar instability was addressed surgically regardless of patient risk factors.

Conclusion

Knee dislocation with associated patellar dislocation is a rare occurrence, but in general can be treated with the standard of care for a knee dislocation and then an assessment of risk factors for consideration of MPFL repair or reconstruction.

Level of evidence

Level 4- systematic review of case reports and case series.

The effect of surgery for multipleligament knee injuries on patellar position and patellofemoral function: a retrospective study

BACKGROUND

Patients who undergo reconstruction for multiligament knee injuries (MLKIs) often exhibit knee instability and poor overall knee function during postoperative follow-up. This may be related to the changes in patellar position and decline in patellofemoral function after surgery.

OBJECTIVE

To evaluate the outcomes following reconstruction of MLKIs through the assessment of: (1) changes in patellar height; (2) anatomical changes in patellofemoral alignment, such as tilt or displacement; and (3) functional outcomes of the patellofemoral joint.

METHODS

This retrospective study included 45 patients who underwent reconstruction for MLKIs at our hospital between November 2015 and September 2022, with complete data and meeting the inclusion criteria. These patients formed the case group. An additional 20 outpatients without ligament injuries or patellar dislocation were selected as the normal control group. Patellar height changes in the case group were assessed preoperatively and postoperatively using the Caton-Deschamps (CD) and Insall-Salvati (IS) indices on lateral X-rays. Magnetic resonance imaging (MRI) was used to measure patellofemoral alignment parameters in both groups, including the sulcus angle (SA), patellar tilt angle (PTA), lateral patellofemoral angle (LPA), congruence angle (CA), and patellofemoral index (PI), to evaluate patellofemoral positioning. Additionally, the Kujala score questionnaire was used to assess the stability function of the patellofemoral joint.

RESULTS

Preoperative patellar height in the case group, measured by the CD and IS indices, was (1.07 ± 0.10, 1.10 ± 0.09), showing a statistically significant difference when compared to postoperative measurements (0.96 ± 0.13, 1.05 ± 0.10) (P < 0.05). However, postoperative patellofemoral alignment parameters, including SA, PTA, LPA, CA, and PI, in the case group showed no statistically significant differences compared to the control group (P > 0.05). At the latest follow-up, the patellofemoral function score in the case group was (89.0 ± 5.3), which was not significantly different from the control group (91.0 ± 2.9) (P > 0.05).

CONCLUSION

After reconstruction of MLKIs, patellar height decreased but remained within the normal range. Patellofemoral alignment was well-maintained, and patellofemoral function was maintained.

Variability in the Spectrum of Reporting on the Schenck KD I Classification in the Orthopaedic Literature: A Systematic Review and Meta-analysis

Background

There has been a marked increase in the number of Schenck knee dislocation (KD) I injuries reported in the multiligament knee (MLK) injury (MLKI) and KD literature.

Purpose

To examine the heterogeneity of the Schenck KD I classification in the MLKI and KD literature.

Study Design

Systematic review; Level of evidence, 4.

Methods

A systematic literature search of PubMed, CINAHL, Scopus, Web of Science, EMBASE, and Cochrane Library was conducted for all studies that investigated KDs and/or MLKIs, utilized the Schenck or an MLKI classification system, and included patients with KD I or MLK 1 injuries. Pooled analysis determined the total number of KD I or MLK 1 injuries and the specific ligamentous tear patterns. Binary meta-analyses of the studies that reported neurovascular injury within each Schenck KD class compared the pooled odds ratio (OR) of vascular and neurological injury in unicruciate (KD I) and bicruciate (KD II-IV) injuries.

Results

Included were 50 studies in which 3460 KD I injuries were reported out of 7872 KDs and MLKIs (43.9%). Of the 2912 patients reported to have had a Schenck KD I injury, 26 patients (0.9%) had a clinically and/or radiographically confirmed tibiofemoral KD. The overall prevalence of Schenck KD I injury with documented tibiofemoral KD was 26 of 7872 (0.3%). A total of 22 studies (n = 1702 patients) reported the specific ligamentous tear patterns; the most common patterns were posterior cruciate ligament (PCL)/lateral collateral ligament (LCL) (n = 526; 30.9%), anterior cruciate ligament (ACL)/LCL (n = 488; 28.7%), ACL/medial collateral ligament (MCL) (n = 408; 24.0%), and PCL/MCL (n = 198; 11.6%). Meta-analyses demonstrated that when compared with bicruciate KD or MLKI, unicruciate KD or MLKI was significantly less likely to have concomitant vascular injury (OR, 0.28; 95% CI, 0.15-0.51; P < .0001) and concomitant neurologic injury (OR, 0.49; 95% CI, 0.37-0.65; P < .00001).

Conclusion

The number of true, clinically and/or radiographically confirmed unicruciate KDs was extremely rare, representing <1% of all reported Schenck KD I injuries. A misappropriation of these injury patterns as true KDs may be taking place, affecting outcome studies and potentially biasing published clinical results. An MLKI classification system must document whether a confirmed KD has occurred.

Patellar Dislocation: Workup and Decision-Making

Acute patellar dislocation (PD) is usually a problem of adolescents and young adults. In most cases, it is a sports-related injury. It is the result of an indirect force on the knee joint, which leads to valgus and external rotation of the tibia relative to the femur. PD is unlikely to occur on a knee with normal patellofemoral joint (PFJ) anatomy. Acute PD consists of an acute injury of the ligamentous medial patellar stabilizers in the background of factors predisposing to patellar instability. These factors are classified into three groups. The first group refers to the integrity of the ligamentous medial patellar restraints, particularly, the medial patellofemoral ligament (MPFL). The second group refers to an abnormal PFJ anatomy, which renders the patella inherently unstable inside the trochlea. The third group refers to the overall axial and torsional profile of the lower limb and to systemic factors, such as ligament laxity and neuromuscular coordination of movement. PD at a younger age is associated with an increased number and severity of patellar instability predisposing factors and lower stress to dislocate the patella. Acute primary PD is usually treated conservatively, while surgical treatment is reserved for recurrent PD. The aim of treatment is to restore the stability and function of the PFJ and to reduce the risk of patellar redislocation. Surgical procedures to treat patellar instability are classified into non-anatomic and anatomic procedures. Non-anatomic procedures are extensor mechanism realignment techniques that aim to center the patella into the trochlear groove. Anatomic procedures aim to restore the PFJ anatomy (ruptured ligaments, osteochondral fractures), which has been severed after the first incident of PD. Anatomic procedures, especially MPFL reconstruction, are more effective in preventing recurrent PD, compared with non-anatomic techniques. Theoretically, all factors that affect PFJ stability should be evaluated and, if possible, addressed. This is practically impossible. Considering that the MPFL ruptures in almost all PDs, MPFL reconstruction is the primary procedure, which is currently selected by most surgeons as a first-line treatment for patients with recurrent PD. Restoration of the axial and torsional alignment of the lower limbs is also increasingly implemented by surgeons. Non-anatomic surgical techniques, such as tibial-tuberosity osteotomy, are used as an adjunct to anatomic procedures. In the presence of multiple PFJ instability factors, acute MPFL reconstruction may be the treatment of choice for acute primary PD as well. Skeletal immaturity of the patient precludes osseous procedures to avoid premature physis closure and subsequent limb deformity. Unfortunately, restoration of the patient's previous activity level or participation in more strenuous sports is questionable and not easy to predict. In the case of competitive athletes, PD may prevent participation in elite levels of sports.

Medial patellofemoral ligament MRI abnormalities in the setting of MCL injuries: are they clinically relevant?

OBJECTIVE

To assess MRI abnormalities of the medial patellofemoral ligament (MPFL) in patients with clinically and MRI-proven superficial medial collateral ligament (sMCL) injuries and determine the clinical significance.

MATERIALS AND METHODS

High-field strength knee MRI examinations were selected which demonstrated sMCL injuries. These cases were retrospectively reviewed for the presence, location, and severity of MPFL abnormality. The MPFL was divided into a more superior transverse component arising from a femoral attachment (tMPFL), and a broader more inferior oblique decussation component (odMPFL) arising from the anterior margin of the upper sMCL. Chart review was performed to determine the clinical relevance of any MPFL findings.

RESULTS

One hundred patients with MCL injury were identified. These included 37 grade I sprains, 33 partial tears, 20 high-grade partial tears, and 10 full thickness tears. Abnormal edema was present at the femoral attachment of the tMPFL in 83%. The odMPFL was abnormal in 90%, most commonly involving the femoral third. No patients had imaging evidence of concurrent lateral patellar dislocation on the initial MRI study. No patients had documented patellofemoral instability at the time of original injury or upon follow-up. No patients required MPFL reconstruction.

CONCLUSION

The MRI appearance of the MPFL is abnormal in the majority of patients with clinically and MRI-documented sMCL sprains and tears. These cases had no evidence of concurrent lateral patellar dislocation on the initial MRI and did not develop patellar instability symptoms.

Collateral Ligament Knee Injuries in Pediatric and Adolescent Athletes

BACKGROUND

The majority of research on medial (MCL) and lateral (LCL) collateral ligament injuries has focused on adults and combined collateral/cruciate injuries. The purpose of this study was to determine characteristics associated with isolated collateral ligament injuries in adolescents, and assess timing for return to sports.

METHODS

Electronic medical records were queried to identify patients aged below 17 years who sustained a magnetic resonance imaging-confirmed isolated MCL or LCL injury over an 8-year period. Retrospective review then documented patient and injury characteristics and clinical course. General linear modeling was used to analyze risk factors for prolonged return to sports, continued pain or reinjury.

RESULTS

Fifty-one knees (33 in males, 65%), mean age 13.8 years (range, 5 to 17), were identified, of which 40 (78%) had MCL injuries. Over half (29, 57%) of knees had an open distal femoral physis including all 5 bony avulsion injuries. Eleven (22%) had LCL injuries of which 3 (6%) had concurrent posterolateral corner injuries. Forty-two (82%) knees had injuries that occurred during sports. Eleven knees (28%) with MCL tears had a simultaneous patellar instability episode. Knee injuries that occurred during sports had 37% shorter recovery time (P=0.02). Eight knees (16%) experienced a reinjury and 12 (24%) were followed over an extended period of time for various knee issues. Football injuries were more likely to be grade 3 (P=0.03), and football and soccer accounted for all grade III injuries. The mean return to sports was 2.2 months, with grade III cases returning at 2.4 months, and 95% of cases within 4 months.

CONCLUSIONS

Isolated collateral ligament injuries are rare in adolescent athletes. MCL injuries, one-quarter of which occurred in conjunction with patellar instability events, were 4 times more common than LCL injuries, one quarter of which have other posterolateral corner structures involved. Grade III injuries represent 20% to 25% of collateral ligament injuries and occurred most commonly in football and soccer.

LEVEL OF EVIDENCE

Level IV-retrospective case series.

Preoperative MRI for the Multiligament Knee Injury: What the Surgeon Needs to Know

The multiligament knee injury is devastating and potentially limb threatening. Preoperative magnetic resonance imaging for the evaluation of the multiligament knee injury is an invaluable clinical tool, and when the radiologist is familiar with how certain injury patterns influence management, optimal outcomes can be achieved. We provide a detailed description of the relationship between salient imaging features of the multiligament knee injury, focusing on the preoperative magnetic resonance imaging, and their influence on clinical decision-making.

The medial patellofemoral complex

PURPOSE OF REVIEW

The purpose of this review is to describe the current understanding of the medial patellofemoral complex, including recent anatomic advances, evaluation of indications for reconstruction with concomitant pathology, and surgical reconstruction techniques.

RECENT FINDINGS

Recent advances in our understanding of MPFC anatomy have found that there are fibers that insert onto the deep quadriceps tendon as well as the patella, thus earning the name "medial patellofemoral complex" to allow for the variability in its anatomy. In MPFC reconstruction, anatomic origin and insertion points and appropriate graft length are critical to prevent overconstraint of the patellofemoral joint. The MPFC is a crucial soft tissue checkrein to lateral patellar translation, and its repair or reconstruction results in good restoration of patellofemoral stability. As our understanding of MPFC anatomy evolves, further studies are needed to apply its relevance in kinematics and surgical applications to its role in maintaining patellar stability.

Outcomes of surgical stabilization in patients with combined ACL deficiency and patellofemoral instability - A case series

BACKGROUND

The purpose of this study was to assess the disease-specific quality of life, and the objective clinical and functional outcomes of patients with symptomatic ACL deficiency and patellofemoral instability following surgical stabilization of both ligaments.

METHODS

Between February 2010 and August 2013, 22 subjects underwent a combined ACL reconstruction and patellofemoral stabilization. The anterior cruciate ligament quality of life questionnaire (ACL-QOL) was completed pre-operatively and two-years post-operatively. Clinical and functional assessments were performed two-years post-operatively. A paired t-test assessed the difference between the pre- and post-operative ACL-QOL scores. Effect size was calculated manually using the Eta squared formula. A Pearson r correlation coefficient assessed for a relationship between the post-operative ACL-QOL scores and functional tests.

RESULTS

Twenty patients completed the 24-month ACL-QOL, 17/20 completed clinical assessment, and 14/20 completed functional testing. The mean pre-operative ACL-QOL score was 21.20 (SD=7.25, range 5.8 to 31.7) and two-years post-operative it was 65.24 (SD=21.38, range 34.5 to 99.1). The paired t-test demonstrated a statistically significant improvement in ACL-QOL scores; t (19)=9.119, p<.001 (two-tailed). The Eta squared statistic (0.81) indicated a very large effect size. Statistically significant correlations (p<.05) were evident between post-operative ACL-QOL scores and all the operative limb single-leg hop tests.

CONCLUSIONS

Combined ACL reconstruction and patellofemoral stabilization surgery leads to good results. This patient cohort with chronic ACL-MPFL injuries demonstrated a statistically significant change in disease-specific quality of life following surgery. In addition, the patient-reported outcomes and objective functional testing results correlated.

LEVEL OF EVIDENCE

Case series - IV.