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 (AP-TTTG), renamed as the sagittal TTTG (sTTTG), has been studied as a measurement to assess the relationship between the two structures in a different direction, potentially representing patellofemoral contact pressures through its assessment in the sagittal plane. 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.

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.

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.

Editorial Commentary: The Medial Patellofemoral Complex Is Composed of the Medial Patellofemoral Ligament and the Medial Quadriceps Tendon-Femoral Ligament: Do We Need to Reconstruct Both?

The medial patellofemoral ligament (MPFL) has been known as the primary soft-tissue restraint to lateral patellar translation. More recent anatomic studies have identified additional fibers that extend to the quadriceps tendon (medial quadriceps tendon-femoral ligament [MQTFL]), leading to the use of the term "medial patellofemoral complex" (MPFC) to describe the broad and variable attachment of this complex on the patella and quadriceps tendon. Whereas many techniques and outcomes of traditional MPFL reconstruction have been described, fewer reports exist on anatomic MPFC reconstruction to recreate both bundles of this complex. To date, the specific biomechanical roles of, and indications for, reconstruction of the MPFL versus MQTFL fibers have not been defined. One primary benefit of MQTFL reconstruction has been to avoid the risk of patella fracture, which is not obviated in the setting of concurrent patellar fixation when reconstructing both components of the MPFC. The risks and benefits comparing fixation on the patella, quadriceps tendon, or both with anatomic double-bundle reconstruction remain to be determined. Additional studies are needed to understand the differences between reconstructing the proximal and distal fibers of the MPFC with regard to graft length changes and femoral attachment sites, in order to optimally recreate the function of each graft bundle in the surgical treatment 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.

Location and Progression of Chondral Injuries at the Time of Revision ACL 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. STUDY DESIGN: Level IV, therapeutic case series.

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.

When the Physician Becomes the Patient: Considerations for Work, Life, and Leadership.

Most orthopaedic surgeons are unprepared for serious medical illnesses. In such cases, the unique work-related and personal considerations for orthopaedic surgeons affect their career, their practice partners, and their patients. Planning together as an orthopaedic business organization for such issues can provide a framework to better navigate these difficult situations. Understanding the considerations and stressors from the individual's perspective can help provide the appropriate level of support while maintaining privacy. Throughout these considerations, open communication regarding expectations and concerns and expressions of empathy are the cornerstones of dealing with physician illness. Being a physician-patient adds complexity to an already difficult and stressful profession. Further dialogue regarding the physician-patient experience can help increase awareness of this issue and allow organizations to create a structure to best manage this almost inevitable occurrence.

What Is the Clinical Benefit of Common Orthopaedic Procedures as Assessed by the PROMIS Versus Other Validated Outcomes Tools?

BACKGROUND: Patient-reported outcome measures (PROMs), including the Patient-reported Outcomes Measurement Information System (PROMIS), are increasingly used to measure healthcare value. The minimum clinically important difference (MCID) is a metric that helps clinicians determine whether a statistically detectable improvement in a PROM after surgical care is likely to be large enough to be important to a patient or to justify an intervention that carries risk and cost. There are two major categories of MCID calculation methods, anchor-based and distribution-based. This variability, coupled with heterogeneous surgical cohorts used for existing MCID values, limits their application to clinical care. QUESTIONS/PURPOSES: In our study, we sought (1) to determine MCID thresholds and attainment percentages for PROMIS after common orthopaedic procedures using distribution-based methods, (2) to use anchor-based MCID values from published studies as a comparison, and (3) to compare MCID attainment percentages using PROMIS scores to other validated outcomes tools such as the Hip Disability and Osteoarthritis Outcome Score (HOOS) and Knee Disability and Osteoarthritis Outcome Score (KOOS). METHODS: This was a retrospective study at two academic medical centers and three community hospitals. The inclusion criteria for this study were patients who were age 18 years or older and who underwent elective THA for osteoarthritis, TKA for osteoarthritis, one-level posterior lumbar fusion for lumbar spinal stenosis or spondylolisthesis, anatomic total shoulder arthroplasty or reverse total shoulder arthroplasty for glenohumeral arthritis or rotator cuff arthropathy, arthroscopic anterior cruciate ligament reconstruction, arthroscopic partial meniscectomy, or arthroscopic rotator cuff repair. This yielded 14,003 patients. Patients undergoing revision operations or surgery for nondegenerative pathologies and patients without preoperative PROMs assessments were excluded, leaving 9925 patients who completed preoperative PROMIS assessments and 9478 who completed other preoperative validated outcomes tools (HOOS, KOOS, numerical rating scale for leg pain, numerical rating scale for back pain, and QuickDASH). Approximately 66% (6529 of 9925) of patients had postoperative PROMIS scores (Physical Function, Mental Health, Pain Intensity, Pain Interference, and Upper Extremity) and were included for analysis. PROMIS scores are population normalized with a mean score of 50 ± 10, with most scores falling between 30 to 70. Approximately 74% (7007 of 9478) of patients had postoperative historical assessment scores and were included for analysis. The proportion who reached the MCID was calculated for each procedure cohort at 6 months of follow-up using distribution-based MCID methods, which included a fraction of the SD (1/2 or 1/3 SD) and minimum detectable change (MDC) using statistical significance (such as the MDC 90 from p < 0.1). Previously published anchor-based MCID thresholds from similar procedure cohorts and analogous PROMs were used to calculate the proportion reaching MCID. RESULTS: Within a given distribution-based method, MCID thresholds for PROMIS assessments were similar across multiple procedures. The MCID threshold ranged between 3.4 and 4.5 points across all procedures using the 1/2 SD method. Except for meniscectomy (3.5 points), the anchor-based PROMIS MCID thresholds (range 4.5 to 8.1 points) were higher than the SD distribution-based MCID values (2.3 to 4.5 points). The difference in MCID thresholds based on the calculation method led to a similar trend in MCID attainment. Using THA as an example, MCID attainment using PROMIS was achieved by 76% of patients using an anchor-based threshold of 7.9 points. However, 82% of THA patients attained MCID using the MDC 95 method (6.1 points), and 88% reached MCID using the 1/2 SD method (3.9 points). Using the HOOS metric (scaled from 0 to 100), 86% of THA patients reached the anchor-based MCID threshold (17.5 points). However, 91% of THA patients attained the MCID using the MDC 90 method (12.5 points), and 93% reached MCID using the 1/2 SD method (8.4 points). In general, the proportion of patients reaching MCID was lower for PROMIS than for other validated outcomes tools; for example, with the 1/2 SD method, 72% of patients who underwent arthroscopic partial meniscectomy reached the MCID on PROMIS Physical Function compared with 86% on KOOS. CONCLUSION: MCID calculations can provide clinical correlation for PROM scores interpretation. The PROMIS form is increasingly used because of its generalizability across diagnoses. However, we found lower proportions of MCID attainment using PROMIS scores compared with historical PROMs. By using historical proportions of attainment on common orthopaedic procedures and a spectrum of MCID calculation techniques, the PROMIS MCID benchmarks are realizable for common orthopaedic procedures. For clinical practices that routinely collect PROMIS scores in the clinical setting, these results can be used by individual surgeons to evaluate personal practice trends and by healthcare systems to quantify whether clinical care initiatives result in meaningful differences. Furthermore, these MCID thresholds can be used by researchers conducting retrospective outcomes research with PROMIS. LEVEL OF EVIDENCE: Level III, therapeutic study.

Editorial Commentary: Handling the (Contact) Pressure in Patellofemoral Surgery: The Role of Lateral Retinacular Release.

The role of lateral retinacular release for the treatment of patellofemoral pathology has evolved over the years. Although once popularized in the treatment of patellofemoral pain and instability, complications such as iatrogenic medial patellar instability and decreases in lateral patellar stability have limited the indications for performing isolated lateral release. However, there exists a need for more clearly defined parameters and understanding of when and how lateral release should be incorporated with other procedures during patellar stabilization and joint-preservation surgery. Advances in finite element analysis, as well as refining our surgical indications and techniques for concurrent lateral release, will allow us to optimize both joint pressures and stability during the surgical management of patellar instability.

Radiographic Landmarks for the Femoral Attachment of the Medial Patellofemoral Complex: A Cadaveric Study.

PURPOSE: To report the radiographic landmarks for the medial patellofemoral complex (MPFC) footprint on the medial femur and describe the difference between the radiographic positions corresponding to the medial quadriceps tendon femoral ligament (MQTFL) and medial patellofemoral ligament (MPFL) fibers. METHODS: In 8 unpaired cadaveric knees, the MPFC footprint was exposed on the medial femur, and the proximal and distal boundaries of the footprint were marked. Lateral fluoroscopic images of the knee were obtained and analyzed using Image J. The proximal boundary corresponding to the MQTFL, the MPFC midpoint, and distal boundary corresponding to the MPFL were described radiographically and compared for differences in position. RESULTS: The proximal MQTFL footprint was 0.8 ± 0.6 mm anterior (P = .013) and 5.2 ± 1.8 mm proximal to the MPFC midpoint (P <.001), whereas the distal MPFL footprint was 0.8 ± 0.7 mm posterior (P = .012) and 5.9 ± 1.1 mm distal to the radiographic MPFC midpoint (P <.001). The radiographic point corresponding to the distal MPFL footprint was 0.8 ± 0.9 mm posterior (P = .011) and 11.1 ± 2.3 mm distal to the radiographic point of the proximal MQTFL footprint (P <.001). When using the point of intersection of the posterior cortical line and the proximal posterior condyle as a reference, 91.6% of all points correlating to the MQTFL, MPFC midpoint and MPFL, were within 10 mm in any direction from this radiographic landmark. CONCLUSIONS: On fluoroscopic imaging, the proximal MQTFL and distal MPFL fibers had significantly different radiographic positions from the MPFC midpoint on the femur. These findings should be considered when reconstructing specific components of the MPFC. CLINICAL RELEVANCE: As fluoroscopy is often used intraoperatively to guide graft placement, our findings may serve as a reference when differentiating the locations of the MPFL vs MQTFL on the femur for anatomic reconstruction.

Arthroscopic Patellofemoral Measurements Can Reliably Assess Patellar Instability.

PURPOSE: To arthroscopically describe patellar position based on lateralization, tilt, and engagement, and compare measurements in normal, medial patellofemoral complex-(MPFC) deficient, and MPFC-reconstructed knees. METHODS: In 10 cadaveric knees, arthroscopic patellar position was assessed by performing digital measurements on arthroscopic images obtained through a standard anterolateral portal. Lateralization was measured as millimeters overhang of the patella past the lateral edge of the lateral femoral condyle, viewing from the lateral gutter. Patellar tilt was calculated as the difference in medial and lateral distances from the patella to the trochlea, viewing from the sunrise view. Patellotrochlear distance was measured as the anteroposterior distance between the central trochlear groove and patella on the sunrise view. Measurements were obtained at 10° intervals of knee flexion from 0° to 90°, in intact knees (group 1), after arthroscopically transecting the MPFC fibers (group 2), and after MPFC reconstruction (group 3). Optimal cutoff values were identified to distinguish between intact versus MPFC-deficient states. RESULTS: When compared to group 1, group 2 demonstrated increased patellar lateralization by 22.5% at 0°-40° knee flexion (P = .006), which corrected to baseline in group 3 (P = .006). Patellar tilt measurements demonstrated no differences between groups. Patellotrochlear distance increased by 21.0% after MPFC transection (P = .031) at 0°-40° knee flexion, with correction to baseline after MPFC reconstruction (P = .031). More than 7 mm of lateral overhang at 20°-30° flexion and >6 mm of patellotrochlear distance at 10°-20° flexion were found to indicate MPFC deficiency. CONCLUSIONS: Utilizing standardized arthroscopic views, we identified significant increases in patellar lateralization and patellotrochlear distance in early knee flexion angles after MPFC transection, and these changes normalized after MPFC reconstruction. CLINICAL RELEVANCE: Arthroscopic assessments of patellar position may be useful in evaluating patellofemoral stability during patellar stabilization surgery.

Editorial Commentary: Trochlear Dysplasia Is Difficult to Measure, No Matter How You Slice It.

Trochlear dysplasia is one of the primary morphologic abnormalities associated with patellar instability. Although qualitative classifications based on trochlear shape such as the Dejour classification exist, radiographic measurements to quantify the severity of trochlear dysplasia are numerous and varied. Each measurement addresses a different element of the complex and wide-ranging presentations that exist along a spectrum of abnormalities in trochlear morphology, and the reported reliability of such measurements are mixed. Overall, our understanding of trochlear dysplasia continues to evolve, and the ability to quantify the morphology of the trochlea, as well as its influence on patellar stability, remains a work in progress. Future directions include developing improved 3-dimensional descriptions of trochlear anatomy, as well as standardizing measurement methods and image slice selection, to better evaluate trochlear morphology in the assessment of patellar instability.

Femoral Origin Anatomy of the Medial Patellofemoral Complex: Implications for Reconstruction.

PURPOSE: To report the shape and orientation of the medial patellofemoral complex (MPFC) footprint on the medial femur and describe the difference between the proximal (medial quadriceps tendon femoral ligament, MQTFL) and distal (medial patellofemoral ligament, MPFL) fibers. METHODS: In 20 cadaveric knees, the MPFC footprint on the medial femur was exposed. Images of the medial femur were analyzed using ImageJ software. The length and width of the MPFC footprint were described to the nearest 0.1 mm; the angle of its long axis was described relative to the axis of the femoral shaft (0.1°). The footprint's most proximal and distal margins were described in relation to the adductor tubercle and medial epicondyle. The differences between each were compared using paired t tests. RESULTS: 17 knees from 10 cadavers were included in this study. The MPFC footprint had a length of 11.7 ± 1.8 mm and a width of 1.7 ± 0.4 mm. The long axis of the footprint was at an angle 14.6° ± 16.6° anterior to the axis of the femoral shaft. The most proximal (MQTFL) fibers originated 7.4 ± 3.8 mm anterior and 1.8 ± 4.7 mm distal to the adductor tubercle and 4.1 ± 2.9 mm posterior and 8.4 ± 5.6 mm proximal to the medial epicondyle. The most distal (MPFL) fibers originated 4.9 ± 4.2 mm anterior and 12.7 ± 4.3 mm distal to the adductor tubercle, as well as 7.1 ± 2.4 mm posterior and 0.5 ± 5.6 mm distal to the medial epicondyle. The distal margin of the femoral MPFC footprint was 10.9 ± 1.7 mm distal (p < .001) and 2.6 ± 3.2 mm more posterior (p = .005) than the proximal margin. CONCLUSIONS: The femoral footprint of the MPFC has a length almost 7 times greater than its width, with the distal margin being 10.9 mm distal and 2.6 mm posterior to the proximal margin. CLINICAL RELEVANCE: This differential anatomy within the femoral origin suggests that MPFL and MQTFL reconstruction may require separate positions of femoral fixation to recreate the anatomy of these fibers.

Editorial Commentary: Repair or Reconstruct? Addressing Medial Patellofemoral Ligament Insufficiency in the Absence of Morphologic Abnormalities.

The role of medial patellofemoral ligament (MPFL) repair versus reconstruction in the treatment of patellar instability continues to undergo debate. Repair of the ligament can be technically less demanding with fewer risks of morbidity, whereas reconstruction carries concerns of graft malpositioning or over-tensioning as well as the risk of patellar fracture. Studies directly comparing the 2 procedures in the setting of recurrent patellar instability have consisted of small series or low levels of evidence that inevitably include patients with concurrent morphologic risk factors such as tuberosity malalignment or patella alta, which are known factors that can influence the biomechanical behavior of the MPFL. Heterogeneity in patient-related risk factors and surgical techniques continues to pose limitations in allowing for direct comparisons between procedures. For the treatment of recurrent patellar instability in the setting of no (or concurrently addressed) morphologic abnormalities, MPFL reconstruction has become a common procedure and generally preferred approach. The superior outcomes associated with reconstruction over repair, however, should be qualified with the fact that attention to the critical details of the technique, including graft position and tension, is paramount to success when performing this procedure.

Editorial Commentary: Socket or Knock It? Considerations in Patellar Fixation During Medial Patellofemoral Ligament Reconstruction.

The medial patellofemoral ligament (MPFL) is the primary static stabilizer to lateral patellar translation, and reconstruction of this ligament has been shown to be successful in reducing dislocation rates and improving functional outcomes in the treatment of patellar instability. Recent studies have warned that complication rates after MPFL reconstruction can be as high as 25%, with patellar fracture being one of the most catastrophic complications that can occur after this procedure. While the use of a bone socket versus cortical fixation on the patella does not appear to influence outcomes, surgeons should take into account the factors of graft and tunnel positioning, graft length/tension, and the need for concurrent procedures in each individual patient when performing this procedure. Any violation of the patella, whether as a socket or for anchor placement, should avoid the anterior cortex and maintain an adequate bony bridge that should be modified according to the patient's anatomy. The optimal technique for MPFL reconstruction continues to evolve, and further studies are needed to identify the ideal type and position of patellar fixation to minimize risks of complications and optimize surgical outcomes when performing MPFL reconstruction in the treatment of patellar instability.

Radiographic Landmarks for the Anterior Attachment of the Medial Patellofemoral Complex.

PURPOSE: Because fluoroscopy is often used in graft placement during patellar stabilization surgery, the purpose of this study was to describe the radiographic landmarks for the anterior attachment midpoint of the medial patellofemoral complex (MPFC). METHODS: Seventeen fresh-frozen cadaveric knees were dissected, and the MPFC was exposed from the articular side after a lateral parapatellar approach. The midpoint of the anterior attachment of the MPFC was identified using a ruler and marked with a pin. Lateral fluoroscopic images of the patella were then obtained and analyzed using digital analysis software. The distance from the superior articular pole to the pin was divided by the length of the articular surface to describe the location of the pin as a percentage of patellar articular length. RESULTS: Of the 17 cadaveric knees, 2 were excluded because of lack of MPFC fibers. In the remaining 15 knees, the mean (±standard deviation) proximal-distal width of the attachment to the patella and/or vastus intermedius tendon was 41 ± 10 mm, spanning from 15 ± 6 mm proximal to the superior pole of the patella to 27 ± 8 mm distal to it. When viewed on lateral fluoroscopic images, the MPFC midpoint was 19% ± 14% of the patellar articular length from the superior articular pole. CONCLUSIONS: In this study, the radiographic landmarks that correlate to the anatomic midpoint of the anterior MPFC attachment are 19% ± 14% of the articular surface from the superior pole of the patella. CLINICAL RELEVANCE: Recent reports on medial patellofemoral ligament anatomy now include fibers that extend to the quadriceps tendon, summarized as the MPFC. With the inclusion of these fibers, the midpoint of the anterior MPFC attachment is more proximal than that of the medial patellofemoral ligament alone. Because fluoroscopy is often used intraoperatively to guide graft placement, this study correlates radiographic landmarks with anatomic findings of the MPFC midpoint on its attachment to the extensor mechanism.

Correction to: Recognition of evolving medial patellofemoral anatomy provides insight for reconstruction.

Unfortunately, the middle name of author was incorrectly published as Jorge A. Chahla instead of Jorge Chahla in the original article.

Recognition of evolving medial patellofemoral anatomy provides insight for reconstruction.

PURPOSE: The scientific literature concerning the anatomy of medial soft-tissue stabilizers of the patella is growing exponentially. Much of the surgical literature has focused on the role of the medial patellofemoral ligament (MPFL) and techniques to reconstruct it, yet our understanding of its anatomy has evolved during the past several years. Given this, we report on the current understanding of medial patellofemoral anatomy and implications for reconstruction. METHODS: Current and historical studies of medial patellar anatomy were reviewed, which include the MPFL and medial quadriceps tendon femoral ligament (MQTFL), as well as that of the distal medial patellar restraints, the medial patellotibial ligament (MPTL) and medial patellomeniscal ligament (MPML). In addition to the reported findings, the authors' anatomic descriptions of each ligament during their dissections were identified and recorded. RESULTS: Despite the name of the MPFL, which implies that the ligament courses between the femur and patella, recent studies have highlighted the proximal MPFL fibers that attach to the quadriceps tendon, known as the MQTFL. The MPFL and MQTFL have also been referred to as the medial patellofemoral complex, reflecting the variability in anatomical attachment sites. The MPFL accounts for only half of the total restraint to lateral patellar displacement, and the remaining contributions to patellar stability are derived from the combination of the MPTL and MPML, which function primarily in greater degrees of knee flexion. CONCLUSION: The understanding of the complexity of the medial patellar stabilizers continues to evolve. Although MPFL reconstruction is gaining wide acceptance as a procedure to treat patellar instability, it is important to recognize the complex and changing understanding of the anatomy of the medial soft-tissue stabilizers and the implications for reconstruction. LEVEL OF EVIDENCE: V.

Tibial tuberosity to trochlear groove distance and its association with patellofemoral osteoarthritis-related structural damage worsening: data from the osteoarthritis initiative.

OBJECTIVES: To determine whether the tibial tuberosity-to-trochlear groove (TT-TG) distance is associated with concurrent patellofemoral joint osteoarthritis (OA)-related structural damage and its worsening on 24-month follow-up magnetic resonance imaging (MRI) in participants in the Osteoarthritis Initiative (OAI). METHODS: Six hundred subjects (one index knee per participant) were assessed. To evaluate patellofemoral OA-related structural damage, baseline and 24-month semiquantitative MRI Osteoarthritis Knee Score (MOAKS) variables for cartilage defects, bone marrow lesions (BMLs), osteophytes, effusion, and synovitis were extracted from available readings. The TT-TG distance was measured in all subjects using baseline MRIs by two musculoskeletal radiologists. The associations between baseline TT-TG distance and concurrent baseline MOAKS variables and their worsening in follow-up MRI were investigated using regression analysis adjusted for variables associated with tibiofemoral and patellofemoral OA. RESULTS: At baseline, increased TT-TG distance was associated with concurrent lateral patellar and trochlear cartilage damages, BML, osteophytes, and knee joint effusion [cross-sectional evaluations; overall odds ratio 95% confidence interval (OR 95% CI): 1.098 (1.045-1.154), p < 0.001]. In the longitudinal analysis, increased TT-TG distance was significantly related to lateral patellar and trochlear cartilage, BML, and joint effusion worsening (overall OR 95% CI: 1.111 (1.056-1.170), p < 0.001). CONCLUSIONS: TT-TG distance was associated with simultaneous lateral patellofemoral OA-related structural damage and its worsening over 24 months. Abnormally lateralized tibial tuberosity may be considered as a risk factor for future patellofemoral OA worsening. KEY POINTS: • Excessive TT-TG distance on MRI is an indicator/predictor of lateral-patellofemoral-OA. • TT-TG is associated with simultaneous lateral-patellofemoral-OA (6-17% chance-increase for each millimeter increase). • TT-TG is associated with longitudinal (24-months) lateral-patellofemoral-OA (5-15% chance-increase for each millimeter).