Medial Quadriceps Tendon Femoral Ligament Reconstruction for Anatomic Reconstruction of the Medial Patellofemoral Complex.

The medial patellofemoral complex (MPFC) refers to the primary static restraint to lateral patellar translation. Originally thought of as the medial patellofemoral ligament, anatomic studies over the past 10 years have identified the additional fibers that attach to the quadriceps tendon, which some have termed the medial quadriceps tendon femoral ligament. Anatomic studies have demonstrated that the MPFC midpoint is at the junction of the medial border of the quadriceps tendon and the articular surface of the patella, indicating that fixation can be on either structure. This technique describes a single-bundle reconstruction technique with anatomic fixation on the quadriceps tendon at the MPFC midpoint that involves fixation on the extensor mechanism first.

Patellofemoral Disorders in Soccer Players.

Patellofemoral disorders are common in the world of soccer and impact players across all levels and ages of the sport. Patellofemoral disorders encompass a spectrum of conditions, from anterior knee pain to patellar instability, and are often influenced by complex biomechanical factors and anatomic variations that can predispose to these conditions. In recent years, there has been a growing emphasis on injury prevention strategies and data-driven approaches, championed by organizations like the Union of European Football Associations and individual professional clubs. Conservative management remains the initial approach for many players, including physical therapy and supportive devices. However, surgical intervention, particularly in cases of recurrent patellar dislocations, is often necessary. The understanding of patellofemoral biomechanics in soccer continues to evolve and offers opportunities for more effective injury prevention and tailored treatment strategies. Despite the challenges, a comprehensive approach to patellofemoral disorders in soccer is essential to preserve player health, enhance performance, and sustain the sport's vitality.

Editorial Commentary: Sagittal Tibial Tuberosity to Trochlear Groove Distance Measurements May Reflect Patellofemoral Contact Pressures.

Tibial tubercle to trochlear groove (TTTG) distance is a commonly utilized measurement in the assessment of knees with patellar instability, representing malalignment in the form of tuberosity lateralization relative to the trochlear groove. More recently, the concept of the anteroposterior TTTG, renamed the sagittal TTTG (sTTTG), has been studied as a measurement to assess the relationship between the 2 structures in the anteroposterior plane, potentially representing patellofemoral contact pressures. How this relates to knee flexion angles is critical to understanding the context of these variables and, in addition, as we attempt to characterize the relationship of sTTTG to trochlear dysplasia that occurs via relative anteriorization of the trochlear floor and posteriorization of the tibial tuberosity. As we incorporate this measurement to capture how our surgical procedures can offload the joint and "correct" the sTTTG distance, the utility of this measurement as a proxy for patellofemoral contact pressures will continue to grow, allowing us to better consider joint preservation in addition to stability in the management of patellar instability.

Patellofemoral instability part 1 (When to operate and soft tissue procedures): State of the art.

Patellofemoral instability is usually initially treated non-operatively. Surgery is considered in patients with recurrent patellar dislocation and after a first-time patellar dislocation in the presence of either an associated osteochondral fracture or high risk of recurrence. Stratifying the risk of recurrence includes evaluating risk factors such as age, trochlear dysplasia, contralateral dislocation, and patellar height. Surgery with soft tissue procedures includes restoring the medial patellar restraints and balancing the lateral side of the joint. Reconstruction of the medial patellofemoral ligament is the most frequent way of addressing the medial soft tissues in patients with patellofemoral instability. Meanwhile, lateral tightness can be achieved by lateral retinaculum lengthening or release. Approaching patellofemoral instability in a patient-specific approach, combined with a shared decision-making process with the patient/family, will guide surgeons to the deliver optimal care for the patellar instability patient.

Relative Energy Deficiency in Sport (REDs) and knee injuries: current concepts for female athletes.

In athletes, a mismatch between caloric intake and energy expended in exercise can eventually lead to Relative Energy Deficiency in Sport (REDs), where the athlete suffers from physiological derangements and decreased sport performance. The prevalence of REDs is higher in females than males. Females are already at a higher risk of knee injuries, which has been attributed to a multitude of factors such as hormonal influences, differences in musculoskeletal anatomy and neuromuscular control compared to males. The literature demonstrates an even higher risk of knee injuries in female athletes with symptoms of REDs. We propose the various factors that influence this risk. A reduction in anabolic hormones can affect muscle development and tendon repair. A relationship between poor neuromuscular control and knee injury has been established, and this can be further worsened in patients with menstrual dysfunction. Chronic deficiency in nutrients such as collagen and vitamin D can result in poorer recovery from microtrauma in tendons and ligaments. All these factors may contribute to increasing the risk of knee injuries, which may include anterior cruciate ligament tears, patella tendinopathy and patellofemoral pain syndrome. This review aims to educate sports clinicians to have a high index of suspicion when treating knee injuries in females; to screen and then manage for REDs if present, for holistic patient care.

Evaluation of Differences in Patellar Height After Patellar Stabilization Procedures Not Intended to Address Patella Alta: A Multicenter Study.

Background: Recent studies have reported conflicting results as to whether isolated medial patellofemoral ligament reconstruction (MPFLr) leads to decreased patellar height. Purpose: To investigate if patellar stabilization surgery not intended to address patella alta influences patellar height. Study Design: Cohort study; Level of evidence, 3. Methods: A multicenter retrospective chart review was conducted, and patients who underwent MPFLr, medializing tibial tuberosity osteotomy (TTO), and/or trochleoplasty between 2016 and 2020 were included. The Caton-Deschamps index (CDI) was calculated from radiographs obtained preoperatively, 2 weeks postoperatively, and 3 months postoperatively. The preoperative CDI value was compared with the 2-week postoperative and 3-month postoperative values according to stabilization procedure (isolated MPFLr, isolated TTO, MPFLr + TTO, MPFLr + trochleoplasty, and MPFLr + trochleoplasty + TTO) using the paired t test. Analyses of the 1-bundle versus 2-bundle MPFLr technique and the presence of lateral retinacular release or lateral retinacular lengthening were conducted on the isolated MPFLr and combined MPFLr + TTO cohorts. Results: A total of 356 knees were included. Statistically significant pre- to postoperative decreases in CDI were seen in all stabilization procedures analyzed (P≤ .017 for all). Within the isolated MPFLr cohort, this significant decrease was seen at 2 weeks postoperatively with the 2-bundle technique (ΔCDI = -0.09; P < .001) but not with the 1-bundle technique (ΔCDI = -0.01; P = .621). Conclusion: The different surgical techniques analyzed in the current study affected patellar height, even when a distalizing TTO was not performed. The decrease was dependent on surgical technique, with a 2-bundle MPFLr leading to a statistically significant decrease and a 1-bundle MPFLr effecting no change.

Editorial Commentary: Diverse Factors Affect Measurement of Patella Alta: Trochlear Morphology and Sagittal Knee Balance Represent Defining Factors of Patellofemoral Stability.

Patella alta is a known risk factor for patellar instability, contributing to increased length changes of the medial patellofemoral complex, and associated with high rates of failure after medial patellofemoral complex reconstruction. Distalization through tibial tuberosity osteotomy (TTO) is a surgical option to address patella alta during patellar stabilization surgery. However, distalization has been shown to have greater complication rates than other types of TTO, and therefore precise indications through proper assessments of patellar height are needed. The Caton-Deschamps index is a commonly used measurement and is independent of patellar tendon length, allowing for assessment of patellar height before and after distalizing TTO. Additional options that may offer this ability are femoral-based measurements such as the patellotrochlear index and sagittal patellar engagement, which also do not rely on the position of the tubercle and may better represent the functional engagement of the patellofemoral joint. However, femoral-based measurements depend on trochlear morphology; theoretically, an advantage of femoral-based measurements is that they may reflect the functional engagement of the patella within the trochlea. However, in knowing the common relation between patella alta and trochlear dysplasia, the question becomes whether an overlap between the patella and a dysplastic proximal trochlea on a sagittal measurement truly represents functional engagement and stability of the patellofemoral joint. Measurement of patella alta and determining indications for distalization can be influenced by measurement techniques including magnetic resonance imaging versus radiography, tibial- versus femoral-based measurements, and positional and morphologic considerations. Increased understanding of trochlear morphology and sagittal knee balance as they relate to patella alta will be important for defining the factors that affect patellofemoral stability.

Hemoglobin A1c Levels >6.6% Are Associated With Higher Postoperative Complications After Anterior Cruciate Ligament Reconstruction.

Purpose: To investigate the relation between hemoglobin A1c (HbA1c) levels and postoperative complications after primary anterior cruciate ligament reconstruction (ACLR). Methods: A retrospective review was performed of consecutive patients with an isolated anterior cruciate ligament tear, preoperative diagnosis of diabetes, and documented HbA1c within 90 days of primary ACLR between 2000 and 2019. Data collected included demographic and surgical characteristics, 90-day medical complications, and subsequent surgeries on the ipsilateral knee. A receiver operating curve was constructed for each HbA1c level in relation to postoperative complications and the optimal cutoff identified via Youden's J statistic. Multivariable logistic regression was performed to assess the relation between postoperative complications and age, sex, graft type, diabetes subtype, and HbA1c. Results: Nineteen patients (7 females, 12 males) fulfilled inclusion criteria with preoperative HbA1c ranging from 5.5 to 10. Complications included septic knee (n = 1) and cyclops lesions requiring arthroscopic lysis (n = 3). Patients with HbA1c of 6.7% or higher were 25 times more likely to experience any postoperative complication (P = .04) and 16 times more likely to require lysis of adhesions (P = .08). On multivariable regression, HbA1c remained significantly associated with any complication (P = .005) and developing arthrofibrosis (P = .02) independent of age, sex, graft type, and diabetes subtype. Conclusions: Diabetic patients undergoing primary ACLR with a preoperative HbA1c of 6.7% or higher were 25 times more likely to require repeat surgical intervention for a postoperative complication. These complications included arthrofibrosis and infection. Strict glycemic control may help minimize the risk of postoperative complications after ACLR. Level of Evidence: Level III, retrospective cohort study.

How Mental Health Affects Injury Risk and Outcomes in Athletes.

CONTEXT: The importance of mental health among athletes is becoming more recognized and valued. Athletes experience symptoms of depression, anxiety, and related mental health disorders at rates similar to those of the general population, but because athletes face unique cultural and environmental pressures, such disorders are exacerbated in the context of an injury. Furthermore, we review the less well-known evidence that mental health disorders in athletes are associated with an increased risk of injury. We discuss the increasing awareness of the deficiencies in mental health support for athletes, which has been especially highlighted during the COVID-19 pandemic as well as in prominent professional and Olympic athletes, and describe both internal and external barriers to appropriate care. EVIDENCE ACQUISITION: We searched PubMed for pertinent peer-reviewed studies. STUDY DESIGN: Clinical review. LEVEL OF EVIDENCE: Level 5. RESULTS: There is a known psychological response to injury that can prolong recovery from musculoskeletal injury; conversely, mental health disorders in athletes are not only associated with an increased injury risk but also portend poorer outcomes subsequently, including prolonged recovery times, increased rates of injury recurrence, decreased rates of return to sport, and reduced performance upon return. Because of inherent barriers to appropriate care of athletes, including identification, stigma, and resource availability, there are currently various ongoing efforts nationally to create and implement initiatives regarding athlete mental health screening, support systems, and directed interventions to address the inextricably linked physical and mental health of athletes. CONCLUSION: Athletic injury negatively impacts the mental health of athletes. Likewise, mental health can and does influence athletic performance and is also intimately tied to the risk of athletic injury, thus creating a complex cycle with inability to separate physical and mental health.

Location and Progression of Chondral Injuries at the Time of Revision Anterior Cruciate Ligament Surgery Varies by Sex.

PURPOSE: To quantify progression of chondral and meniscal injuries between primary and revision anterior cruciate ligament (ACL) surgery. METHODS: Patients who underwent both index and revision ACL reconstruction between 2000 and 2020 at our institution were identified, and dates of injury and surgery, demographics, and clinical data were obtained from operative reports. Outerbridge grade was recorded in each compartment, along with presence and location of meniscal injury. The frequency of each injury between first and second cases was calculated. Differences in injury and progression were compared over time as well as between patient sex and age. RESULTS: The study included 189 patients (96 female, 93 male). Age at first surgery was 31.7 ± 13.2 years. Mean time to second injury was 3.3 ± 3.0 years. In total, 116 patients had a new or previous chondral injury (odds ratio, 1.6; 95% CI, 1.2-2.1). The medial femoral condyle (31%) and the patella (21%) accounted for the highest proportion of new injury to articular surfaces, whereas new injury to menisci was comparable between the medial (25%) and lateral (23%) meniscus. At the time of revision ACL reconstruction, females had a high prevalence of chondral injuries to the lateral compartment, whereas males had a high prevalence of chondral injury to the medial femoral condyle. The prevalence of new chondral injuries was comparable between sexes, with males having a slightly higher proportion. While time between surgeries, sex, and age had graphical evidence of moderating risk, the effects were small and imprecise. CONCLUSIONS: Revision ACL reconstruction carried a 1.6 increase in the odds for new or progressive chondral lesions in our cohort. At the time of revision, females had a relatively higher proportion of lateral-sided chondral injuries, whereas males had a relatively higher proportion of medial femoral condyle injuries. The greatest increase in the prevalence of new and progressive lesions was observed in the medial femoral condyle and trochlea. This progression appeared to be moderated by time between surgeries, patient sex, and age; however, the differences were small and imprecise. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Telemedicine After COVID-19: Incorporating Virtual Visits Into Your Practice.

The use of telemedicine services within orthopaedics increased rapidly as a result of the COVID-19 pandemic. Telemedicine may improve access to care and save time and money for patients and clinicians; however, limitations such as technical issues and limited physical examination may reduce its widespread adoption. Virtual visits generally produce equivalent satisfaction and clinical outcomes compared with those performed in person. Although telemedicine has served many different roles within orthopaedic practices, its main utility is for patients who have to travel significant distances and for visits that do not require physical examination to determine a treatment plan. Several regulations govern the use of telemedicine. Most notably, clinicians must be licensed to practice medicine in the state in which the patient is located during the appointment. Although compliance issues remain a potential source of legal issues, experts cite misdiagnosis from limited physical examination as the most likely reason for medical liability. Clinicians should be familiar with techniques for virtual physical examination and should provide instruction to patients before the visit to optimize data obtained.

Radiographic Landmark Measurements for the Femoral Footprint of the Medial Patellofemoral Complex May Be Affected by Visible Femoral Shaft Length on Lateral Knee Radiographs.

PURPOSE: To assess the effect of visible femoral shaft length on the accuracy of radiographic landmarks of the medial patellofemoral complex (MPFC). METHODS: In 9 cadaveric knees, the MPFC footprint was exposed on the medial femur, and its proximal and distal boundaries were marked. Lateral fluoroscopic images of the knee were assessed in 1-cm length increments, beginning 1 cm proximal to the medial condyle and continuing proximally to 8 cm. The MPFC midpoint was described on each image relative to the posterior cortical line of the femur and a line perpendicular to this line through the proximal margin of the medial condyle. In addition, the MPFC midpoint was assessed relative to a line from the proximal posterior cortex to the midpoint of Blumensaat line. RESULTS: Using the posterior cortical line as a reference, the MPFC radiographic landmark moved anteriorly with decreasing visible femoral shaft on radiographs, particularly at 4 cm and less. However, no proximal-distal change was noted. Linear regression analysis demonstrated a relationship between visible femoral shaft and MPFC position on radiographs (R = 0.461, R2 = 0.212, B = -0.636, P < .001). For every centimeter decrease in the visible femoral shaft, the radiographic MPFC footprint moved anteriorly by 0.636 mm. Receiver operating characteristic curve analysis revealed that a minimum of 4 cm of femoral shaft on lateral radiographs is required for accurate MPFC footprint localization (area under the curve = 0.80; sensitivity = 76.7%; specificity = 69.0%; P < .001). In contrast, no anterior-posterior change was seen when referencing a line from the proximal posterior cortex to the midpoint of Blumensaat line. CONCLUSIONS: When using the posterior cortical line to identify the midpoint of the MPFC, at least 4 cm of femoral shaft should be visible for accurate assessment. If less than 4 cm of shaft is visible, a line through the midpoint of Blumensaat line and the proximal posterior cortex can be used as an alternative method to estimate the position of the femoral footprint. CLINICAL RELEVANCE: As fluoroscopy is frequently used intraoperatively for MPFC reconstruction, our findings may serve as a guide when assessing femoral tunnel placement on fluoroscopy.

A modified Delphi consensus statement on patellar instability: part II.

Aims: The aim of this study was to establish consensus statements on medial patellofemoral ligament (MPFL) reconstruction, anteromedialization tibial tubercle osteotomy, trochleoplasty, and rehabilitation and return to sporting activity in patients with patellar instability, using the modified Delphi process. Methods: This was the second part of a study dealing with these aspects of management in these patients. As in part I, a total of 60 surgeons from 11 countries contributed to the development of consensus statements based on their expertise in this area. They were assigned to one of seven working groups defined by subtopics of interest. Consensus was defined as achieving between 80% and 89% agreement, strong consensus was defined as between 90% and 99% agreement, and 100% agreement was considered unanimous. Results: Of 41 questions and statements on patellar instability, none achieved unanimous consensus, 19 achieved strong consensus, 15 achieved consensus, and seven did not achieve consensus. Conclusion: Most statements reached some degree of consensus, without any achieving unanimous consensus. There was no consensus on the use of anchors in MPFL reconstruction, and the order of fixation of the graft (patella first versus femur first). There was also no consensus on the indications for trochleoplasty or its effect on the viability of the cartilage after elevation of the osteochondral flap. There was also no consensus on postoperative immobilization or weightbearing, or whether paediatric patients should avoid an early return to sport.

Adding Tibial Tuberosity Medialization to Medial Patellofemoral Ligament Reconstruction Reduces Lateral Patellar Maltracking During Multidirectional Motion in a Computational Simulation Model.

Purpose: To determine whether adding tibial tuberosity medialization to medial patellofemoral ligament (MPFL) reconstruction reduces lateral patellar maltracking during a dynamic multidirectional activity and to investigate when medial patellofemoral contact pressures are elevated during daily activities, such as squatting. Methods: Seven computational models representing knees with patellar instability, including lateral patellar maltracking, were evaluated following simulated MPFL reconstruction (bisect offset index > .75). Tibial tuberosity medialization was added to MPFL reconstruction for each model. Patellar tracking during multidirectional motion was evaluated by simulating pivot landing. Analysis of pivoting focused on early flexion (5° to 40°). Patellofemoral contact pressures during daily function were evaluated by simulating knee squatting. Data were analyzed with paired comparisons between MPFL reconstruction with and without tuberosity medialization. Results: The patella dislocated during pivoting for 2 models with an isolated MPFL reconstruction and for 1 model including tibial tuberosity medialization. Adding tibial tuberosity medialization to MPFL reconstruction significantly decreased bisect offset index by ∼0.1 from 5° to 40° (P < .03). For knee squatting, medializing the tibial tuberosity significantly increased maximum medial contract pressure by ∼0.5 MPa from 30° to 85° (P < .05) but did not significantly influence maximum lateral pressure. Conclusions: In this study of simulated multidirectional motion, MPFL reconstruction did not sufficiently constrain the patella for some knees. Adding tibial tuberosity medialization to MPFL reconstruction in these models reduced lateral patellar maltracking during multidirectional motion but increased pressure applied to medial cartilage during squatting. Clinical Relevance: After establishing the influence of tibial tuberosity medialization on patellar maltracking for an idealized population, as was done in the current study, future simulation studies can be performed to better determine the anatomical characteristics of patients for whom tibial tuberosity medialization is needed to reduce the risk of postoperative patellar maltracking.

Team Approach: Improving Orthopaedic Operating Room Efficiency.

The cost of surgical care accounts for almost one-third of all health care spending in the United States. Within health care spending, the operating room (OR) is one of the largest health care costs during a perioperative episode of care. Efficiency in the OR has been associated with increased productivity, safety, and quality of care. However, multiple sources of delays can contribute to inefficiency, and improving efficiency in the OR requires a systematic approach to identify and address each issue. We report on the case of a process improvement initiative implemented in a large academic institution to improve OR efficiency in outpatient orthopaedic cases, and we discuss the lessons learned through this program. Optimizing workflow in the OR requires a multidisciplinary team approach consisting of clinician leaders with common goals and open discussion regarding the needs of each team member, including circulating nurses, surgical nurses/technologists, and anesthesiologists. Our experience highlights the importance of practical, clinician-driven changes that are supported by administrative engagement, resources for staffing and equipment, and institutional flexibility, which are required to implement systemic changes to address and improve efficiency in the OR.

Association of Trochlear Length on Sagittal MRI to Trochlear Dysplasia in Knees With Patellar Instability.

Background: Trochlear dysplasia is a primary risk factor for patellar instability and leads to loss of the osteochondral constraint of the patella. Trochleoplasty techniques include the Peterson grooveplasty, which alters the length of the trochlea; however, a radiographic measurement of trochlear length to support this has not been described. Purpose: To describe measurements to quantify trochlear length on sagittal magnetic resonance imaging in patients with and without patellar instability and to correlate trochlear length with measurements of trochlear dysplasia. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A total of 66 age- and sex-matched knees (36 female and 30 male; mean age, 20.8 ± 4.8 years) were included in this study, of which 33 had patellar instability. Trochlear extension length (TEL) and trochlear alpha angle (TAA) were measured on 3 sagittal magnetic resonance imaging scans (center of the knee, center of the medial condyle, and center of the lateral condyle), and measurements were compared between symptomatic and control knees. Receiver operating characteristic curve analysis was performed, and the area under the curve (AUC) was calculated to describe the accuracy of each measurement to distinguish between knees with and without patellar instability. Linear and multivariate regression analyses were performed to assess the relationship between sagittal measurements and axial measurements of trochlear dysplasia, including lateral trochlear inclination, sulcus angle, and trochlear depth, as well as patient size reflected by the epicondylar distance. Results: In symptomatic knees, the central trochlea extended more proximally than in control knees, as determined by the TEL (14.0 ± 3.0 vs 11.5 ± 2.3 mm, respectively; P < .001) and TAA (68.4° ± 3.8° vs 70.5° ± 3.4°, respectively; P = .017). AUC calculations showed that a TEL ≥11 mm at the central trochlea was predictive of patellar instability in both male and female knees (AUC = 0.83 and 0.77, respectively), as was a TAA ≤67° in female knees (AUC = 0.72). An independent association between the central TEL and sulcus angle was found. The central TEL showed a weak correlation with patient size, as measured by the epicondylar distance, while the TAA did not. Conclusion: In knees with symptomatic patellar instability, the central trochlea was found to extend 2.5 mm more proximally than in control knees, and this increase in length correlated with severity of trochlear dysplasia. As radiographic examinations of the trochlea and grooveplasty procedures are often based on the proximal extent of the cartilaginous trochlea, further studies are needed to identify the role of trochlear length in the assessment and treatment of trochlear dysplasia in the setting of patellar instability.

Medial Patellofemoral Reconstruction Techniques for Patellar Instability.

The medial patellofemoral complex (MPFC) is the term used to describe the primary soft tissue stabilizer of the patella, which consists of fibers that attach to the patella (medial patellofemoral ligament, or MPFL), and the quadriceps tendon (medial quadriceps tendon femoral ligament, or MQTFL). Despite the variability of its attachment on the extensor mechanism, the midpoint of this complex is consistently at the junction of the medial quadriceps tendon with the articular surface of the patella, indicating that either patellar or quadriceps tendon fixation can be used for anatomic reconstruction. Multiple techniques exist to reconstruct the MPFC, including graft fixation on the patella, quadriceps tendon, or both structures. Various techniques using several graft types and fixation devices have all reported good outcomes. Regardless of the location of fixation on the extensor mechanism, elements critical to the success of the procedure include anatomic femoral tunnel placement, avoiding placing undue tension on the graft, and addressing concurrent morphological risk factors when present. This infographic reviews the anatomy and techniques for the reconstruction of the MPFC, including graft configuration, type, and fixation, while addressing common pearls and pitfalls in the surgical treatment of patellar instability.

In Vivo Length Changes Between the Attachments of the Medial Patellofemoral Complex Fibers in Knees With Anatomic Risk Factors for Patellar Instability.

BACKGROUND: Medial patellofemoral complex (MPFC) reconstruction plays an important role in the surgical treatment of patellar instability. Anatomic reconstruction is critical in re-creating the native function of the ligament, which includes minimizing length changes that occur in early flexion. Anatomic risk factors for patellar instability such as trochlear dysplasia, patella alta, and increased tibial tuberosity to trochlear groove (TT-TG) distance have been shown to influence the function of the MPFC graft in cadaveric studies, but the native length change patterns of the MPFC fibers in knees with anatomic risk factors have not been described. PURPOSE: To describe the in vivo length changes of the MPFC fibers in knees with anatomic risk factors for patellar instability and identify the optimal attachment sites for MPFC reconstruction. STUDY DESIGN: Controlled laboratory study. METHODS: Dynamic computed tomography imaging was performed on the asymptomatic knee in patients with contralateral patellar instability. Three-dimensional digital knee models were created to assess knees between 0° and 50° of flexion in 10° increments. MPFC fiber lengths were calculated at each flexion angle between known anatomic attachment points on the extensor mechanism (quadriceps tendon, MPFC midpoint [M], and patella) and femur (1, 2, and 3, representing the proximal to distal femoral footprint). Changes in MPFC fiber length were compared for each condition and assessed for their relationships to morphologic risk factors (trochlear depth, Caton Deschamps Index [CDI], and TT-TG distance). RESULTS: In 22 knees, native MPFC fibers were found to be longer at 0° than at 20° to 50° of flexion. Length changes observed between 0° and 50° increased with the number of risk factors present. In the central fibers of the MPFC (M-2), 1.7% ± 3.1% length change was noted in knees with no anatomic risk factors, which increased to 5.6% ± 4.6%, 17.0% ± 6.4%, and 26.7% ± 6.8% in the setting of 1, 2, and 3 risk factors, respectively. Nonanatomic patella-based attachments were more likely to demonstrate unfavorable length change patterns, in which length was greater at 50° than 0°. In patellar attachments, an independent relationship was found between increasing length changes and TT-TG distance, while in quadriceps tendon attachments, a trend toward a negative relationship between length changes and CDI was noted. All configurations demonstrated a strong relationship between percentage change in length and number of morphologic risk factors present, with the greatest influence found in patella-based attachments. CONCLUSION: The MPFC fibers demonstrated increased length changes in knees when a greater number of morphological risk factors for patellar instability were present, which worsened in the setting of nonanatomic configurations. This suggests that the function of the intact MPFC in patients with anatomic risk factors may not reflect previously described findings in anatomically normal knees. Further studies are needed to understand the pathoanatomy related to these changes, as well as the implications for graft placement and assessment of length changes during MPFC reconstruction techniques. CLINICAL RELEVANCE: MPFC length change patterns vary based on the number of morphologic risk factors for patellar instability present and should be considered during reconstructive procedures.

Redefining Trochlear Dysplasia: Normal Thresholds Vary by Measurement Technique, Landmarks, and Sex.

BACKGROUND: Trochlear dysplasia is a known risk factor for patellar instability. Multiple radiographic measurements exist to assess trochlear morphology, but the optimal measurement technique and threshold for instability are unknown. PURPOSE: To describe the optimal measurements and thresholds for trochlear dysplasia on magnetic resonance imaging (MRI) that can identify knees with patellar instability in male and female patients. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 3. METHODS: Knee MRI scans of patients with patellar instability were compared with those of age- and sex-matched controls. Measurements of the sulcus angle, lateral trochlear inclination (LTI), and trochlear depth were performed on axial images using bony and cartilaginous landmarks. Receiver operating characteristic curve analysis was performed, with the area under the curve (AUC) describing the accuracy of each diagnostic test. Optimal cutoff values were calculated to distinguish between knees with and without patellar instability. AUC and cutoff values were reported for each measurement as well as for male and female subgroups. RESULTS: A total of 238 knee MRI scans were included in this study (138 female, 100 male; age range, 18-39 years). Trochlear depth measurements had the greatest diagnostic value, with AUCs of 0.79 and 0.82 on bone and cartilage, respectively. All measurements (sulcus angle, LTI, trochlear depth) on bone and cartilage had an AUC ≥0.7 (range, 0.70-0.86), with optimal cutoff values of 145° (bone) and 154° (cartilage) for the sulcus angle, 17° (bone) and 13° (cartilage) for LTI, and 4 mm (bone) and 3 mm (cartilage) for trochlear depth. Optimal cutoff values in female patients varied from those in male patients for all measurements except for cartilaginous trochlear depth. CONCLUSION: Normal thresholds for trochlear dysplasia varied based on the use of bony versus cartilaginous landmarks. Cartilaginous trochlear depth measurements had the greatest ability to identify knees with patellar instability. Furthermore, optimal cutoff values for all measurements except for cartilaginous trochlear depth differed between female and male patients. These findings suggest that sex-specific parameters of normal values may be needed in the assessment of risk factors for patellofemoral instability.

Rehabilitation of anterior knee pain in the pregnant athlete: Considerations and modifications by trimester.

BACKGROUND: Anterior knee pain is a common symptom many females experience during pregnancy. There are several musculoskeletal changes that occur in anatomy and physiology throughout the course of pregnancy that impact the lower extremity kinetic chain. Pregnant athletes, recreational through competitive, who attempt to maintain a high activity level through each trimester may be at increased risk for anterior knee pain due to a greater demand for lumbopelvic and hip stabilization. CLINICAL QUESTION: What are the evidence-driven rehabilitation guidelines and specific modifications needed to treat anterior knee pain in the female athlete during each trimester of pregnancy? KEY RESULTS: We aim to provide an overview of rehabilitation treatment guidelines for pregnant females with anterior knee pain, presenting specific physiological changes and rationale for modifications, discussed by trimester. We recommend our program be conducted under the supervision of a physical therapist working closely with the athlete's obstetrics and sports medicine team. CLINICAL APPLICATION: The number of women who are active during pregnancy is increasing. We provide an overview of the guidelines and considerations for treating women with anterior knee pain during a healthy and uneventful pregnancy.