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.
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.
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.
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.
Arthroscopic assessments of patellar position may be useful in evaluating patellofemoral stability during patellar stabilization surgery.
To read this article in full you will need to make a payment
Purchase one-time access:Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
One-time access price info
- For academic or personal research use, select 'Academic and Personal'
- For corporate R&D use, select 'Corporate R&D Professionals'
Subscribe:Subscribe to Arthroscopy
Already a print subscriber? Claim online access
Already an online subscriber? Sign in
Register: Create an account
Institutional Access: Sign in to ScienceDirect
- Variability in the patellar attachment of the medial patellofemoral ligament.Arthroscopy. 2016; 32: 1667-1670
- The anatomic midpoint of the attachment of the medial patellofemoral complex.J Bone Joint Surg Am. 2016; 98: 1199-1205
- The anatomy and reconstruction of the medial patellofemoral ligament.Knee. 2003; 10: 221-227
- Anatomic study of the attachment of the medial patellofemoral ligament and its characteristic relationships to the vastus intermedius.Knee Surg Sports Traumatol Arthrosc. 2013; 21: 305-310
- Shape and size of the medial patellofemoral ligament for the best surgical reconstruction: a human cadaveric study.Knee Surg Sports Traumatol Arthrosc. 2014; 22: 2327-2333
- Anatomy of the medial patello-femoral ligament: A systematic review of the last 20 years literature.Musculoskelet Surg. 2015; 99: 93-103
- Acute lateral patellar dislocation at MR imaging: Injury patterns of medial patellar soft-tissue restraints and osteochondral injuries of the inferomedial patella.Radiology. 2002; 225: 736-743
- Clinical outcome after reconstruction of the medial patellofemoral ligament in patients with recurrent patella instability.Knee Surg Sports Traumatol Arthrosc. 2014; 22: 2458-2464
- The ability of medial patellofemoral ligament reconstruction to correct patellar kinematics and contact mechanics in the presence of a lateralized tibial tubercle.Am J Sports Med. 2015; 43: 2198-2207
- Variations in kinematics and function following patellar stabilization including tibial tuberosity realignment.Knee Surg Sports Traumatol Arthrosc. 2014; 22: 2350-2356
- A systematic review of complications and failures associated with medial patellofemoral ligament reconstruction for recurrent patellar dislocation.Am J Sports Med. 2012; 40: 1916-1923
- Complications of medial patellofemoral ligament reconstruction in young patients.Am J Sports Med. 2013; 41: 1030-1038
- Complications of medial patellofemoral ligament reconstruction: common technical errors and factors for success: AAOS exhibit selection.J Bone Joint Surg Am. 2012; 94: e87
- Use of a superolateral portal and 70° arthroscope to optimize visualization of patellofemoral tracking and osteochondral lesions in patients with recurrent patellar instability.Arthrosc Tech. 2020; 9: e1731-e1736
- Physical and arthroscopic examination techniques of the patellofemoral joint.J Orthop Sports Phys Ther. 1998; 28: 277-285
- Empty sunrise sign: An arthroscopic finding in recurrent patellar dislocation.J Knee Surg. 2020; 33: 89-93
- Differential contributions of the quadriceps and patellar attachments of the proximal medial patellar restraints to resisting lateral patellar translation.Arthroscopy. 2020; 36: 1670-1676
- Medial patellofemoral ligament restraint in lateral patellar translation and reconstruction.Knee. 2000; 7: 121-127
- Medial soft tissue restraints in lateral patellar instability and repair.Clin Orthop Relat Res. 1998; 349: 174-182
- Arthroscopic extraarticular reconstruction of the medial patellofemoral ligament with gracilis tendon autograft—Surgical technique.Knee Surg Sports Traumatol Arthrosc. 2012; 20: 1245-1251
- Radiographic landmarks for femoral tunnel placement in medial patellofemoral ligament reconstruction.Am J Sports Med. 2007; 35: 801-804
- Medial patellofemoral ligament reconstruction: Impact of knee flexion angle during graft fixation on dynamic patellofemoral contact pressure—A biomechanical study.Arthroscopy. 2018; 34: 1072-1082
- Allowing one quadrant of patellar lateral translation during medial patellofemoral ligament reconstruction successfully limits maltracking without overconstraining the patella.Knee Surg Sports Traumatol Arthrosc. 2018; 26: 2883-2890
- Intraclass correlations: uses in assessing rater reliability.Psychol Bull. 1979; 86: 420-428
- Anatomy and biomechanics of the medial patellofemoral ligament.Knee. 2003; 10: 215-220
- Medial patellotibial ligament reconstruction improves patella tracking when combined with medial patellofemoral reconstruction: An in vitro kinematic study.Arthroscopy. 2020; 36: 2501-2509
- Dynamic simulation of the effects of graft fixation errors during medial patellofemoral ligament reconstruction.Orthop J Sports Med. 2016; 4 (2325967116665080)
- Roentgenographic analysis of patellofemoral congruence.J Bone Joint Surg Am. 1974; 56: 1391-1396
- Magnetic resonance imaging of patellofemoral relationships.Skeletal Radiol. 1993; 22: 403-410
- The biomechanics of medial patellofemoral ligament repair followed by lateral retinacular release.Am J Sports Med. 2010; 38: 1462-1467
- Arthroscopic image distortion. Part II: The effect of lens angle and portal location in a 3D knee model.Knee Surg Sports Traumatol Arthrosc. 2016; 24: 2072-2078
- Intercondylar notch measurement during arthroscopy and on preoperative magnetic resonance imaging.Arthrosc Tech. 2019; 8: e1263-e1267
- Poor accuracy and interobserver reliability of knee arthroscopy measurements are improved by the use of variable angle elongated probes.Ann Rheum Dis. 2002; 61: 540-543
Published online: July 09, 2021
Accepted: June 29, 2021
Received: February 17, 2021
The authors report the following potential conflicts of interest or sources of funding: B.L. and G.W. report nonfinancial research support from Arthrex, Inc., during the conduct of the study. Full ICMJE author disclosure forms are available for this article online, as supplementary material.
© 2021 by the Arthroscopy Association of North America