Patient selection for lateral retinacular release (LRR) and its efficacy are controversial. Iatrogenic medial subluxation can occur with inappropriate LRR. The aim of this study was to determine the reduction in patellofemoral stability with progressively more extensive LRR. The force required to displace the patella 10mm medially and laterally in nine cadaveric knees was measured with and without loading of the quadriceps and iliotibial band. The knee was tested intact, then after progressive release beginning proximal to the patella (PR), the mid-level between the proximal and distal limit of the patella (MR) where the fibres are more transverse, then distally till Gerdy's tubercle (DR) and finally the joint capsule (CR). Both medial and lateral stability decreased with progressive releases, larger for the medial. The MR caused a significant reduction of lateral stability between 30 degrees and 90 degrees of knee flexion. There was an 8% reduction in medial stability at 0 degrees flexion with a complete LRR (DR). A comparable reduction in medial stability in the loaded knee at 20 degrees and 30 degrees flexion was obtained with MR alone, with no further reduction after DR. A capsular release caused a further reduction in medial stability at 0 degrees and 20 degrees and this was marked in the unloaded knee. In extension, the main lateral restraint was the joint capsule. At 30 degrees flexion, the transverse fibres were the main contributor to the lateral restraint.
"Lateral retinacular release has been performed by some authors on patients with a positive no thumb test or poor patellar alignment during TKA,11,12) but its impact on the blood supply of the patella remains controversial.13,14) "
[Show abstract][Hide abstract] ABSTRACT: We would like to analyze the risk factors of no thumb test among knee alignment tests during total knee arthroplasty surgery.
The 156 cases of total knee arthroplasty by an operator from October 2009 to April 2010 were analyzed according to preoperative indicators including body weight, height, degree of varus deformity, and patella subluxation and surgical indicators such as pre-osteotomy patella thickness, degree of patella degeneration, no thumb test which was evaluated after medial prepatella incision and before bone resection (1st test), no thumb test which was evaluated with corrective valgus stress (2nd test, J test), and the kind of prosthesis. We comparatively analyzed indicators affecting no thumb test (3rd test).
There was no relation between age, sex, and body weight and no thumb test (3rd test). Patellar sulcus angle (p = 0.795), patellar congruence angle (p = 0.276) and preoperative mechanical axis showed no relationship. The 1st no thumb test (p = 0.007) and 2nd test (p = 0.002) showed significant relation with the 3rd no thumb test. Among surgical indicators, pre-osteotomy patella thickness (p = 0.275) and degeneration of patella (p = 0.320) were not relevant but post-osteotomy patellar thickness (p = 0.002) was relevant to no thumb test (3rd test). According to prosthesis, there was no significance with Nexgen (p = 0.575). However, there was significant correlation between Scorpio (p = 0.011), Vanguard (p = 0.049) and no thumb test (3rd test). Especially, Scorpio had a tendency to dislocate the patella, but Vanguard to stabilize the patella.
No thumb test (3rd test) is correlated positively with 1st test, 2nd test, and post-osteotomy patella thickness. Therefore, the more patella osteotomy and the prosthesis with high affinity to patellofemoral alignment would be required for correct patella alignment.
Clinics in orthopedic surgery 12/2011; 3(4):274-8. DOI:10.4055/cios.2011.3.4.274
"We do know that the lateral retinacular structures help to resist patellar lateral subluxation when the knee is near extension (Christoforakis et al., 2006), and it has been shown recently that the transverse ITB–patellar band is slack when the knee is extended and tightens significantly in flexion (Ghosh et al., 2009), so it could be speculated that the ITB–patellar band acts when the knee is flexed. This has recently been shown: releasing the capsular structures reduced patellar medial stability significantly from 0° to 20° knee flexion, releasing the ITB–patellar band reduced the stability significantly from 30° to 90° knee flexion (Merican et al., 2009). Similarly, Ostermeier et al. (2007b) found that a lateral retinacular release allowed the patella to translate and tilt medially, compared with the intact condition, despite having not loaded the vastus lateralis or iliotibial band in their experiment. "
[Show abstract][Hide abstract] ABSTRACT: Although lateral retinacular releases are not uncommon, there is very little scientific knowledge about the properties of these tissues, on which to base a rationale for the surgery. We hypothesised that we could identify specific tissue bands and measure their structural properties. Eight fresh-frozen knees were dissected, and the lateral soft tissues prepared into three distinct structures: a broad tissue band linking the iliotibial band (ITB) to the patella, and two capsular ligaments: patellofemoral and patellomeniscal. These were individually tensile tested to failure by gripping the patella in a vice jaw and the soft tissues in a freezing clamp. Results: the ITB-patellar band was strongest, at a mean of 582N, and stiffest, at 97 N/mm. The patellofemoral ligament failed at 172 N with 16 N/mm stiffness; the patellomeniscal ligament failed at 85 N, with 13N/mm stiffness. These structural properties suggest that most of the load in-vivo is transmitted to the patella by the transverse fibres that originate from the ITB.
Journal of Biomechanics 08/2009; 42(14):2323-9. DOI:10.1016/j.jbiomech.2009.06.049 · 2.75 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Since a dysplastic trochlea has been identified as the main pathomorphology in recurrent patellofemoral instability, trochleoplasty became a surgical solution in some of these cases. However, in comparison to other surgical procedures stabilizing the patellofemoral joint, trochleoplasty is a major operation with an arthrotomy, and associated typical risks of open surgery such as arthrofibrosis. Therefore, we developed a technique to perform an arthroscopic deepening trochleoplasty via suprapatellar portals using shaver burrs. Comparable to the open procedure, a cartilage flake is released and a new bony trochlea is created according to the normal anatomy. Then, the cartilage flake is re-fixated using Vicryl tapes and anchors. This method seems to be an obvious advantage in patellofemoral surgery, since an arthrotomy can be avoided, and postoperative pain as well as soft tissue healing time can be reduced.
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