Extensile medial parapatellar approach to the distal femur and knee

The Extensile Medial Parapatellar Approach to the Distal Femur and Knee: Anatomic Landmarks and Surgical Technique, Stevens, Jarrad; Clement, Nicholas, D.; Patton, James, T. Techniques in Orthopaedics (2018) published ahead of print.

Abstract:

This paper describes an extensile surgical approach to the distal femur, which incorporates the medial parapatellar arthrotomy. This extensile exposure serves as an anterior utility approach to the knee, allowing the surgeon access to all aspects of the anterior knee and near circumferential access to the distal femur. Reported indications for access to this region include: tumor resection, difficult primary arthroplasty and revision arthroplasty of the knee, and intra-articular and extra-articular fractures of the distal femur. Despite adequate working knowledge of the standard medial parapatellar approach to the knee, the extensile approach is seldom required and, as a result, orthopedic trainees and practising orthopedic surgeons may not be familiar with the musculotendonous junctions that occur in the quadriceps tendon. This report describes a novel surgical approach and the relevant anatomy through a series of detailed clinical and fresh cadaveric dissections. A previously undescribed anatomic landmark is demonstrated through photographs and cadaveric variation studies, which may help guide the surgeon in defining crucial planes.

fat-stripe-junction-vastus-medialis
The fat stripe (arrow) identifying the non-adherent junction vastus medialis and rectus femoris. FS indicates fat stripe; M, medial; P, proximal.

Single-use and patient-specific instrumentation can be reliably used in primary total knee arthroplasty

patient-specific-knee

Can a Single-Use and Patient-Specific Instrumentation Be Reliably Used in Primary Total Knee Arthroplasty? A Multicenter Controlled Study, by Abane et al. Arthroplasty (2018)

Abstract

Background
The aim of this controlled multicenter study is to evaluate the clinical and radiologic outcomes of primary total knee arthroplasty (TKA) using single-use fully disposable and patient-specific cutting guides (SU) and compare the results to those obtained with traditional patient-specific cutting guides (PSI) vs conventional instrumentation (CI).

Methods
Seventy consecutive patients had their TKA performed using SU. They were compared to 140 historical patients requiring TKA that were randomized to have the procedure performed using PSI vs CI. The primary measure outcome was mechanical axis as measured on a standing long-leg radiograph using the hip-knee-ankle angle. Secondary outcome measures were Knee Society and Oxford knee scores, operative time, need for postoperative transfusion, and length of hospital stay.

Results
The mean hip-knee-ankle value was 179.8° (standard deviation [SD] 3.1°), 179.2° (SD 2.9°), and 178.3° (SD 2.5°) in the CI, PSI and SU groups, respectively (P = .0082). Outliers were identified in 16 of 65 (24.6%), 15 of 67 (22.4%), and 14 of 70 (20.0%) knees in the CI, PSI, and SU group, respectively (P = .81). There was no significant difference in the clinical results (P = .29 and .19, respectively). Operative time, number of unit transfusion, and length of hospital stay were not significantly different between the 3 groups (P = .45, .31, and 0.98, respectively).

Conclusion
The use of an SU in TKA provided similar clinical and radiologic results to those obtained with traditional PSI and CI. The potential economic advantages of single-use instrumentation in primary TKA require further investigation.

Keywords
total knee arthroplastysingle useinstrumentationpatient specificoutcomes

Level of Evidence
Therapeutic Level II

Posterior cruciate ligament a twisted and flat structure, and the tibio-femoral ligament

Posterior cruciate ligament is twisted and flat structure: new prospective on anatomical morphology, by Kato et al. KSSTA (2018) 26(1):31–39

Abstract:

Purpose
This cadaveric study aimed to elucidate PCL morphology by observing the anatomical relationship with other structures and the fibre layers of the PCL in cross section for remnant preserving PCL reconstruction.

Methods
Seventeen fresh-frozen cadaveric knees were studied, using the clock-face method to analyse the anatomical relationship between the PCL and Humphrey’s ligament. The width and thickness of the PCL, Humphrey’s and Wrisberg’s ligaments were measured. The PCL was cut sharply perpendicular to the tibia shaft, and the fibre layers were observed in cross section.

Results
The PCL was located between 12 and 4 o’clock in the right knee (8 and 12 o’clock in the left), while Humphrey’s ligament was located between 2 and 4 o’clock in the right knee (8 and 10 o’clock in the left). Humphrey’s ligament at femoral insertion, midsubstance and lateral meniscus insertion averaged 8.7 ± 2.3, 5.9 ± 2.1 and 6.1 ± 2.0 mm, respectively, while the thickness at each level averaged 2.0 ± 1.2, 1.6 ± 0.6 and 1.9 ± 0.6 mm. The width of the PCL at midsubstance and at medial meniscus level averaged 13.3 ± 2.0 and 11.0 ± 1.6 mm, respectively, while the thickness of the PCL averaged 5.4 ± 0.8 and 5.5 ± 1.4 mm. In cross section, multiple, interconnected layers were observed which could not be divided. The main layers at each level were aligned from the posterolateral to the anteromedial aspect and formed a C-shape at the medial meniscus level.

Conclusion
The PCL at midsubstance is flat. PCL appears as a twisted ribbon composed of many small fibres without clearly separate bundles. When remnant preserving PCL reconstruction is performed, it is necessary to take account of not only PCL morphology but also the ligaments of Humphrey and Wrisberg. These findings may affect the PCL footprint and the graft shape in the future remnant preserving PCL reconstruction.

kato2017-Wrisberg-tibio-femoral-ligament
The variability of Wrisberg’s ligament. The “tibio-femoral” ligament.

Interesting excerpts:

Frequency of the ligaments of Humphrey and Wrisberg
Humphrey’s ligament alone was found in 6 out of 17 specimens (35.3%), while Wrisberg’s ligament alone was found in 3 out of 17 specimens (17.6%). Both were observed in 8 out of 17 specimens (47.1%).

The clock‑face method and the angle measurement for the ligaments of Humphrey and Wrisberg
All right PCLs were located between 12 and 4 o’clock; meanwhile, all right Humphrey’s ligaments were located between 2 and 4 o’clock. All left PCLs were located between 8 and 12 o’clock; meanwhile, all left Humphrey’s ligaments were located between 8 and 10 o’clock. The angle of the PCL averaged 86.4 ± 4.4°, whereas the angle of Humphrey’s ligament averaged 45.2 ± 8.7°. The angle of Wrisberg’s ligament averaged 34.1 ± 4.4°.

The variability of Wrisberg’s ligament
The “tibio-femoral” ligament, a posterior medial oblique ligament, covered the PCL like Wrisberg’s ligament in four specimens (Fig. 3a). This posterior ligament was superficial to the PCL and attached to the tibia more laterally than the PCL in spite of the same femoral attachment of Wrisberg’s ligament. Because the layer was obviously different from the PCL, it was recognized that this ligament did not form part of the PCL. This ligament was observed in the knees that did not have the typical Wrisberg’s ligament. It was named the “tibio-femoral” ligament, distinct from the PCL.

Morphology of the PCL and the fibre layers in cross section
The PCL is composed of many small fibres (Fig. 1). A relatively flat structure could be observed at the midsubstance (Fig. 4a), while multiple layers were observed in cross section. The layers connected with each other and could not be divided. The main layers observed in the cross section were aligned from the posterolateral to the anteromedial direction at the midsubstance, but formed a C-shape at the level of the medial meniscus (Fig. 4b). The axis of the arc was aligned in a similar direction at midsubstance.

ACL tibial footprint is elliptical or triangular shaped in healthy young adults (3-T MRI analysis)

Anterior cruciate ligament tibial insertion site is elliptical or triangular shaped in healthy young adults: high-resolution 3-T MRI analysis, Tashiro et al. KSSTA (2018) 26(2):485-490.

Abstract:

Purpose
To clarify the morphology of anterior cruciate ligament (ACL) tibial insertion site in healthy young knees using high-resolution 3-T MRI.

Methods
Subjects were 50 ACL-reconstructed patients with a mean age of 21.4 ± 6.8 years. The contralateral healthy knees were scanned using high-resolution 3-T MRI. The tibial insertion sites of the anteromedial (AM) and posterolateral (PL) bundle fibres, and the ACL attachment on the anterior horn of lateral meniscus (AHLM) were segmented from the MR images, and 3D models were reconstructed to evaluate the morphology. The shape of ACL footprint was qualitatively analysed, and the size of AM and PL attachments and AHLM overlapped area was measured digitally.

Results
Tibial AM and PL bundles were clearly identified in 42 of 50 knees (84.0%). Morphology of the whole ACL tibial insertion site was elliptical in 23 knees (54.8%) and triangular in 19 knees (45.2%), but not classified as C-shape in any knees. However, the AM bundle attachment was of C-shape in 29 knees (69.0%) and band-like in 13 knees (31.0%). Overlap of ACL on AHLM was found in 26 knees (61.9%), and the size of the overlapped area was 4.8 ± 4.7% of the whole ACL insertion site.

Conclusion
3D morphology of the intact ACL tibial insertion site analysed by high-resolution 3-T MRI was elliptical or triangular in healthy young knees. However, the AM bundle insertion site was of C-shape or band-like. A small lateral portion of the ACL was overlapped with the AHLM. As for clinical relevance, these findings should be considered in order to reproduce the native ACL insertion site sufficiently.

Level of evidence
III.

tashiro2017-ACL-footprint-bundles
If PL bundle was eliminated, AM bundle footprint looked C-shape (a) in 29 knees (69.0%) and band-like in 13 knees (31.0%) (b)

Preoperative MRI predicts eligibility for arthroscopic primary ACL repair

ACL-tear-tipe-II

Preoperative magnetic resonance imaging predicts eligibility for arthroscopic primary anterior cruciate ligament repair, by van der List and DiFelice, KSSTA (2018), 26(2):660–671

Abstract:

Purpose
To assess the role of preoperative magnetic resonance imaging (MRI) on the eligibility for arthroscopic primary anterior cruciate ligament (ACL) repair.

Methods
All patients undergoing ACL surgery between 2008 and 2017 were included. Patients underwent arthroscopic primary repair if sufficient tissue length and quality were present, or they underwent single-bundle ACL reconstruction. Preoperative MRI tear locations were graded with the modified Sherman classification: type I (>90% distal remnant length), type II (75–90%), or type III (25–75%). MRI tissue quality was graded as good, fair, or poor. Arthroscopy videos were reviewed for tissue length and quality, and final treatment.

Results
Sixty-three repair patients and 67 reconstruction patients were included. Repair patients had more often type I tears (41 vs. 4%, p < 0.001) and good tissue quality (89 vs. 12%, p < 0.001). Preoperative MRI tear location and tissue quality predicted eligibility for primary repair: 90% of all type I tears and 88% of type II tears with good tissue quality were repaired, while only 23% of type II tears with fair tissue quality, 0% of type II tears with poor tissue quality, and 14% of all type III tears could be repaired. Conclusions This study showed that tear location and tissue quality on preoperative MRI can predict eligibility for arthroscopic primary ACL repair. These findings may guide the orthopaedic surgeon on the preoperative assessment for arthroscopic primary repair of proximal ACL tears. Level of evidence Level IV.

ACL-tear-MRI-repair-flowchart
Flowchart, based on preoperative MRI tear location and tissue quality, shows the percentage of patients that were repaired per tear location and tissue quality

The importance of Blumensaat’s line morphology for accurate femoral ACL footprint evaluation using the quadrant method

The importance of Blumensaat’s line morphology for accurate femoral ACL footprint evaluation using the quadrant method, by Yahagi, Iriuchishima,, Horaguchi, et al. KSSTA (2018) 26(2):455–461.

Morphological variation of the Blumensaat’s line
Following Iriuchishima’s classification*, the morphology of the Blumensaat’s line was classified into straight, small hill, and large hill types.

Straight type
The Blumensaat’s line (intercondylar roof) appeared more or less straight, and the transition from the Blumensaat’s line to the posterior cortex was clearly defined.

Small hill type
A protrusion spanning less than half of the line was observed at the posterior (proximal) part of the Blumensaat’s line.

Large hill type
A protrusion spanning more than half of the line was observed at the proximal part of the the Blumensaat’s line.

*Iriuchishima T, Ryu K, Aizawa S, Fu FH (2016) Blumensaat’s line is not always straight: morphological variations of the lateral wall of the femoral intercondylar notch. Knee Surg Sports Traumatol Arthrosc 24:2752–2757

iriuchishima-blumensaat-line-morphology
Morphological variations of the Blumensaat’s line. In Iriuchishima’s classification, the morphology of the Blumensaat’s line has three types of variations: straight type, small hill type, and large hill type

Grid placement in the quadrant method
In the same images used for the morphological evaluation of the Blumensaat’s line, four types of quadrant grid placement were evaluated according to the morphological variations of the Blumensaat’s line and the chondral lesion

  • Grid (1) Without consideration of hill existence and not including the chondral lesion. The baseline of the quadrant grid was matched to the anterior part of the Blumensaat’s line. The lower and side line of the grid were tangential to the medial wall of the lateral femoral condyle.
  • Grid (2) Without consideration of hill existence and including the chondral lesion. The base line of the grid was determined as in Grid 1. The lower and side line were tangential to the articular surface.
  • Grid (3) With consideration of hill existence and not including the chondral lesion. The baseline of the grid was the line connecting the anterior edge of the Blumensaat’s line and the top of the hill. The lower and side line of the grid were tangential to the medial wall of the lateral femoral condyle.
  • Grid (4) With consideration of hill existence and including the chondral lesion. The baseline of the grid was determined as in Grid 3. The lower and side line were tangential to the articular surface. The measurement accuracy of the Image J software were, 0.1 mm and 0.1 mm2.
yahagi2017-quadrant-grid-placement
Quadrant grid placement according to the morphological variations of the Blumensaat’s line and the chondral lesion. According to the morphological variations of the Blumensaat’s line and the chondral lesion, quadrant grids were placed as: Grid (1) without consideration of hill existence and not including the chondral lesion. Grid (2) without consideration of hill existence and including the chondral lesion. Grid (3) with consideration of hill existence and not including the chondral lesion. Grid (4) with consideration of hill existence and including the chondral lesion

3D graft-bending angle measurement and finite-element analysis

3D-FEM-ACL-graft

Peak stresses shift from femoral tunnel aperture to tibial tunnel aperture in lateral tibial tunnel ACL reconstructions: a 3D graft-bending angle measurement and finite-element analysis, by Van Der Bracht et al. KSSTA (2018) 26(2): 508–517.

Abstract:

Purpose
To investigate the effect of tibial tunnel orientation on graft-bending angle and stress distribution in the ACL graft.

Methods
Eight cadaveric knees were scanned in extension, 45°, 90°, and full flexion. 3D reconstructions with anatomically placed anterior cruciate ligament (ACL) grafts were constructed with Mimics 14.12®. 3D graft-bending angles were measured for classic medial tibial tunnels (MTT) and lateral tibial tunnels (LTT) with different drill-guide angles (DGA) (45°, 55°, 65°, and 75°). A pivot shift was performed on 1 knee in a finite-element analysis. The peak stresses in the graft were calculated for eight different tibial tunnel orientations.

Results
In a classic anatomical ACL repair, the largest graft-bending angle and peak stresses are seen at the femoral tunnel aperture. The use of a different DGA at the tibial side does not change the graft-bending angle at the femoral side or magnitude of peak stresses significantly. When using LTT, the largest graft-bending angles and peak stresses are seen at the tibial tunnel aperture.

Conclusion
In a classic anatomical ACL repair, peak stresses in the ACL graft are found at the femoral tunnel aperture. When an LTT is used, peak stresses are similar compared to classic ACL repairs, but the location of the peak stress will shift from the femoral tunnel aperture towards the tibial tunnel aperture. Clinical relevance: the risk of graft rupture is similar for both MTTs and LTTs, but the location of graft rupture changes from the femoral tunnel aperture towards the tibial tunnel aperture, respectively.