The highly accurate anteriolateral portal for injecting the knee

This project was in compliance with the Helsinki Declaration, approved by the institutional review board (IRB), and is registered at ClinicalTrials.gov (Clinical Trial Identifier NCT00651625). Inclusion criteria included: 1) osteoarthritis of the knee; 2) Brandt grades 1-3 osteoarthritis as diagnosed by radiographs, 2) persistent pain in the involved joint, 3) significant pain in the involved joint by 10 cm Visual Analogue Pain Sale (VAS) where VAS ≥ 5 cm, 4) failure of exercise and oral analgesics, and 5) the recommendation from the physician for an intraarticular injection [9, 19] (6,50). Exclusion criteria included 1) Brandt grade 4 osteoarthritis, 2) hemorrhagic diathesis, 3) the use of warfarin or antiplatelet therapy, or 4) the presence of infection (6). A total of 83 knees with osteoarthritis were randomized between the lateral midpatellar portal (40 knees) and the modified anteriolateral portal (43 knees) (% difference: +8%; 95% CI: -8% to +9%, p = 0.50). Subject age (midpatellar: 61 ± 10 yr; anteriolateral: 59 ± 14 yr; % difference: -3%; 95% CI: -12% to +6%, p = 0.47), female gender (midpatellar: 80%; anteriolateral: 88%; % difference: +13%; 95% CI: -10% to +31%; p = 0.47), subjects who completed study (100% for both, p = 0.5), and pre-procedure baseline pain (10 cm VAS; midpatellar: 8.1 ± 2.0 cm; anteriolateral: 7.6 ± 2.2 cm; % difference: -6%; 95% CI: -18% to +5%; p = 0.28) were similar between the two treatment groups. Outcomes included procedural pain and injection pain, significant pain (VAS ≥ 5 cm), VAS pain scores at outcome (2 weeks and 6 months), mean change in VAS pain scores at outcome, responders (asymptomatic joints at outcome defined by VAS < 2 cm), non-responders (symptomatic joints at outcome defined by VAS ≥ 2 cm), duration of therapeutic effect (months), and time to reinjection or referral to surgery (months). Cost-effectiveness was not calculated because this is highly dependent on reimbursement that varies widely from country to country [20].

The one-needle two-syringe technique was used where 1) one needle is used for anesthesia, arthrocentesis, hydrodissection, and intraarticular injection; 2) the first syringe is used to anesthetize, aspirate effusion, and hydrodissect and dilate the joint space, and 3) the second syringe is used to inject the intraarticular therapy [9]. For the modified anteriolateral portal, relevant anatomic landmarks (patella, patellar tendon, lateral tibial plateau, lateral femoral condyle, and medical femoral condyle were palpated and marked with ink (Figure 1 and 2). The anteriolateral portal was defined by the adjoining structures of inferiolateral border of the patellar, the patellar tendon, and the lateral tibial plateau. Rather than directing the needle to the traditional anteriolateral target, the intercondylar notch, the modified anteriolateral approach targets the synovial membrane of the medial femoral condyle (Figure 3) [2, 9, 21]. This requires directing the needle from the anteriolateral portal under the patellar tendon through the anterior fat pad, until the needle tip directly penetrates the synovial membrane and the bevel engages the medial femoral condyle (Figure 3) [9]. The lateral midpatellar injection was performed with the knee almost fully extended (in 10 to 15 degrees of flexion), and the needle was directed from the lateral surface of the knee to the middle of the patellofemoral joint (Figure 4) [2].

A 21 gauge 2.0 inch (5.1-cm) needle (305783-21 g BD Needle, BD, 1 Becton Drive, Franklin Lakes, NJ 07417, website: http://​www.​bd.​com) was mounted on a 3 ml mechanical syringe, the reciprocating procedure device (RPD syringe) (AVANCA Medical Devices, Inc, Albuquerque, New Mexico, USA. website: http://​www.​AVANCAMedical.​com). For very large individuals a 3.0 inch (7.7 cm) 21 gauge needle was used instead. The RPD mechanical syringe is formed around the core of a conventional syringe barrel and plunger, but has a parallel injection plunger and an accessory barrel to control the motion of the injection plunger (Figure 2, 3, and 4). The two plungers are mechanically linked by a pulley in an opposing fashion, resulting in a set of reciprocating plungers. Thus, when the aspiration plunger is depressed with thumb, the mechanical syringe aspirates, and when the injection plunger is depressed with the thumb, the syringe injects. This permits the index and middle fingers to remain in one position during both aspiration and injection, while the thumb only needs to move in a horizontal plane to the alternative plunger in order to change the direction of aspiration or injection. Mechanical syringes permit easy detection of small amounts of synovial fluid that flash back into the barrel confirming true intraarticular positioning [9, 22‐25]. Prior to the procedure the mechanical syringe was filled with 1% lidocaine (3 ml for the knee) (Xylocaine^® 1%, AstraZeneca Pharmaceuticals LP, 1800 Concord Pike, P.O. Box 15437, Wilmington, DE 19850-5437). While alternatively aspirating and injection, the needle tip was directed from the anteriolateral portal across the knee towards the medial femoral condyle until the needle tip penetrated the synovial membrane and the needle encountered firm resistance to further advance (Figure 2 and 3).

After the needle was advanced to the surface of the medial femoral condyle, the lidocaine was injected intraarticularly to hydrodissect and lift the synovial membrane over the needle bevel, and using one hand to hold the mechanical syringe and the other hand the needle hub, the mechanical syringe was rotated off the intraarticular needle, and a 3 ml conventional syringe prefilled with 80 mg triamcinolone acetonide suspension (Kenalog^® 40, Westwood-Squibb Pharmaceuticals, Inc (Bristol-Myers Squibb), 345 Park Ave, New York, NY 10154-0004, USA) was rotated onto the intraarticular needle, and the treatment was injected. The needle was extracted, and firm pressure applied to the puncture site.

To determine the intraarticular injection accuracy of the modified anteriolateral bent knee portal, 76 consecutive osteoarthritic knees fulfilling the above criteria were injected using the bent knee modified anteriolateral portal, and needle positioning and fluid flow determined by sonography. To determine accuracy of needle placement with sonography, the observer placed the long axis of the ultrasound transducer over the anteriomedial portion of the knee, such that the transducer was parallel to the needle shaft and thus the ultrasound beam vector would best approximate 90 degrees to the long axis of the needle, providing optimal reflected ultrasound signal and excellent visualization of the needle (Figure 5 and 6) [9]. A portable ultrasound unit with a 10-5 MHz 38 mm broadband liner array transducer (Sonosite M-Turbo, SonoSite, Inc. 21919 30th Drive SE, Bothell, WA 98021) was used to sonographically determine the location of the medial femoral condyle, the position of the needle tip, intraarticular and extraarticular fluid flow, and dilation of the intraarticular space.

Two positions of the needle tip were tested: 1) when the needle palpably engaged the medial femoral condyle, and 2) when the needle did not palpably engage the medial fem femoral condyle. True intraarticular positioning was established by demonstrating the sonographic characteristics of the needle tip: 1) anatomic positioning of the needle tip at the interface of synovial membrane and cartilage (Figure 3 and 6), 2) demonstration of the free flow of fluid from the needle tip into the intraarticular space and not into the anterior fat pad (Figure 7), and 3) demonstration of dilation of the intraarticular space with the injected fluid [9, 14, 26‐29] (Figure 7). Extraarticular injection was determined by observing 1) fluid movement into the anterior fat pad or retroflow of fluid back along the needle shaft, 2) increased echogenicity in the septa of the anterior fat pad, and 3) lack of fluid movement into and dilation of the intraarticular space [9].

Data were entered into Excel (Version 5, Microsoft, Seattle, WA), and analyzed in SAS (SAS/STAT Software, Release 6.11, Cary, NC). Differences in measurement data were determined with the student t-test; categorical data were determined with Fisher's Exact Test, while differences between multiple parametric data sets were determined with Fishers Least Significant Difference Method.