Abstract
Arthroscopic outside-in meniscal repair technique, which was first described by Warren in 1985, including all its later modifications, involved tying the final knot on the outer surface of the capsule. Capsular-side knot-tying has reported complications such as catching sensory nerves under the knot with resultant postoperative focal sensory loss and paresthesia, as well as pain under the skin because of irritation from the knot. Meniscus-side-knot-tying technique involves tying the knot on the outer surface of the meniscus. Advantages of the meniscus-side knot-tying technique include the following: avoiding catching nerves under the knot; avoiding pain under the skin because of irritation from the knot; the tension of the sliding knot and the subsequent half hitches, which can be monitored accurately under vision; no skin incisions needed; no possibility of cutting the suture limbs while performing the skin incision between the two needle holes; and, the ability to suture tears in mobile parts of the meniscus without fixing them to the capsule like tears in the anterior horn of the lateral meniscus.
Technique Video
Meniscus-side-knot-tying technique in arthroscopic outside-in meniscal repair has several advantages over the capsular-side-knot-tying: avoiding catching nerves under the knot; avoiding pain under the skin because of irritation from the knot; the tension of the sliding knot and the subsequent half hitches can be monitored accurately under vision; no skin incisions needed; the ability to suture tears in mobile parts of the meniscus without fixing them to the capsule like tears in the anterior horn of the lateral meniscus; and no possibility of cutting the suture limbs while performing the skin incision between the 2 needle holes.
The arthroscopic outside-in meniscal repair technique was first described by Warren1 in 1985. The technique was developed mainly to avoid the neurovascular complications and large skin incisions associated with the arthroscopic inside-out meniscal repair technique at that time.1,2 The outside-in meniscal repair technique is specifically indicated in (1) anterior horn meniscal tears, which are difficult to repair using inside-out or all-inside meniscal repair techniques; (2) suturing a meniscal transplant either allograft or synthetic scaffold; and (3) small knee joints of children when other techniques involve using a relatively large instruments and devices that might cause iatrogenic cartilage injuries.
The original Warren’s technique (Fig. 1) involved the insertion of an 18-gauge spinal needle from outside the joint through the meniscal tear, followed by passing a polydioxanone suture, which is then grasped, and a knot is tied at the end to allow the meniscus to be pulled into a reduced position. A second spinal needle is introduced, and the same procedure is repeated. A knot is tied between the 2 sutures on the outer surface of the capsule after a small skin incision is made between the 2 needle holes.1,3
Fig 1.
Warren arthroscopic outside-in meniscal repair technique. Green arrow points to the capsular-side-knot-tying technique.
Over the last 38 years and since the emergence of Warren’s technique, several modifications have followed. However, all modifications involved tying the final knot on the outer surface of the capsule.4, 5, 6, 7, 8, 9, 10
Surgical Technique (Video 1)
Instrumentation
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1.
Two 18-gauge needles loaded with 2 monofilament nonabsorbable 2-0 suture materials.
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2.
Suture Loop Horizontal Grasper (Suture Retriever) (Smith & Nephew, London, UK).
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3.
Arthroscopic Pusher/Cutter (Knot Pusher Suture Cutter) (Mitek; Depuy Synthes, Johnson & Johnson, New Brunswick, NJ).
Surgical Steps
The procedure is performed with the patient under general or spinal anesthesia. A tourniquet is always used. Diagnostic arthroscopy is first performed, and the reparability of the meniscal tear is determined. Debridement of the meniscal tear site, perisynovial shaving, needling of the outer fragment of the meniscal tear, and microfracturing of the notch are all performed to enhance healing. The suture material loaded in the first needle is bent at the needle tip performing a loop, and the needle is then inserted from outside to inside the joint, penetrating the skin, subcutaneous tissue, capsule, and synovium (at a level that makes the suture visible in the distance between the synovium and the outer surface of the meniscus) (Fig. 2). The needle is further advanced to penetrate the outer fragment of the meniscal tear (Fig. 3), tear site (Fig. 4), and inner fragment of meniscal tear (Fig. 5). The second needle loaded with another loop is inserted in the same manner, 2 to 3 mm anterior to the first needle (Fig. 6). The second needle is further advanced to penetrate the outer fragment of the medial meniscal tear, tear site, and the inner fragment of the tear (Fig. 7). The 2 needles are pulled with a rotatory motion outside the joint, keeping the 2 loops inside the joint (Fig. 8). With a suture retriever inserted from the ipsilateral portal, the posterior loop is pulled through the anterior loop (Fig. 9a), transforming it into a single thread outside the joint (Fig. 9b). The anterior loop inside the joint is pulled outside the joint, driving the suture thread outside the joint as well (Fig. 10a), creating a horizontal suture (Fig. 10b). The 2 suture threads lying in the plain between the synovium and the outer surface of the meniscus are grasped with a suture retriever (Fig. 11a) and pulled outside the joint via the ipsilateral portal (Fig. 11b). Using the 2 suture threads outside the ipsilateral portal, a sliding arthroscopic knot is made and pushed inside the joint using a knot-pusher-suture-cutter through the anteromedial portal to the outer surface of the meniscus (Fig. 12a). The tension of the knot is monitored under vision (Fig. 12b). Several half hitches are then performed over the sliding knot, and their tensions are also monitored under vision (Fig. 13). Using the knot-pusher-suture-cutter, the 2 threads are cut close to the outer surface of the meniscus (Fig. 14). The procedure is repeated, performing the appropriate number of sutures as needed to repair the meniscal tear (Fig. 15).
Fig 2.
Arthroscope is in anterolateral portal of a right knee flexed 90°. The first needle loaded with a loop is inserted from outside to inside the joint penetrating the skin, subcutaneous tissue, capsule, and synovium (at a level that make the suture visible in the distance between the synovium and the outer surface of the meniscus). Green arrow points to the tip of the first needle loaded with a loop folded at its tip.
Fig 3.
Arthroscope is in anterolateral portal of a right knee flexed 90°. The first needle is further advanced from outside to inside to penetrate the outer fragment of medial meniscal tear. Green arrow points to the site where the first needle penetrates the outer fragment of the medial meniscal tear.
Fig 4.
Arthroscope is in anterolateral portal of a right knee flexed 90°. The first needle is further advanced from outside to inside to pass through the medial meniscal tear site. Green arrow points to the site where the first needle passes through the medial meniscal tear site.
Fig 5.
Arthroscope is in anterolateral portal of a right knee flexed 90°. The first needle is further advanced from outside to inside to penetrate the inner fragment of the medial meniscal tear. Green arrow points to the first needle tip after penetrating the inner fragment of the medial meniscal tear.
Fig 6.
Arthroscope is in anterolateral portal of a right knee flexed 90°. The second needle loaded with a second loop is inserted in the same manner, 2 to 3 mm anterior to the first needle. Green arrow points to the second needle loaded with a loop folded at its tip.
Fig 7.
Arthroscope is in anterolateral portal of a right knee flexed 90°. The second needle is further advanced to penetrate the outer fragment of the medial meniscal tear, tear site and the inner fragment of the tear. Green arrow points to the second needle tip after penetration of the outer fragment of the medial meniscal tear, tear site, and inner fragment of the tear.
Fig 8.
Arthroscope is in anterolateral portal of a right knee flexed 90°. The two needles are pulled with a rotatory motion outside the joint keeping the two loops inside the joint. Green arrow points to the second needle pulled outside the joint using a rotatory motion.
Fig 9.
Arthroscope is in anterolateral portal of a right knee flexed 90°. (a) With a suture retriever inserted from the ipsilateral portal (anteromedial portal), (b) the posterior loop is pulled through the anterior loop, transforming it into a single thread outside the joint. Green arrow points to the straightened first loop transformed into a single thread and pulled through the second loop outside the joint using a suture retriever.
Fig 10.
Arthroscope is in anterolateral portal of a right knee flexed 90°. (a) The remaining loop (anterior loop) inside the joint is pulled outside the joint driving the suture thread (former posterior loop) outside the joint too, (b) creating a horizontal suture. Green arrow in (a) points to the anterior loop pulled outside the joint driving the single thread (former posterior loop) outside the joint too creating a horizontal suture. Green arrow in (b) points to the horizontal suture at the femoral surface of the inner fragment of the medial meniscal tear.
Fig 11.
Arthroscope is in anterolateral portal of a right knee flexed 90°. (a) The two suture threads lying in the plain between the synovium and the outer fragment of the medial meniscal tear are grasped with a suture retriever (inserted via the anteromedial portal) and (b) pulled outside the joint through the ipsilateral portal (anteromedial portal). Green arrows point to the two suture threads lying in the plain between the synovium and the outer fragment of the medial meniscal tear.
Fig 12.
Arthroscope is in anterolateral portal of a right knee flexed 90°. (a) Using the 2 suture threads outside the ipsilateral portal, a sliding arthroscopic knot is created and pushed inside the joint using a knot-pusher-suture-cutter through the anteromedial portal to the outer surface of the meniscus. The tension of the knot is monitored under vision. Green arrow in (a) points to the sliding arthroscopic knot being pushed inside the joint using a knot-pusher-suture-cutter. Green arrow in (b) points to the monitoring of the tension of the sliding knot under vision.
Fig 13.
Arthroscope is in anterolateral portal of a right knee flexed 90°. Several half hitches are then performed using the knot-pusher-suture-cutter (inserted via the anteromedial) portal over the sliding knot, and their tensions are also monitored under vision. Green arrow points to a half hitch being tensioned under vision using the knot-pusher-suture-cutter.
Fig 14.
Arthroscope is in anterolateral portal of a right knee flexed 90°. Using the knot-pusher-suture-cutter (inserted via the anteromedial portal), the 2 threads are cut close to the outer surface of the meniscus. Green arrow points to a suture thread that has been cut using a knot-pusher-suture-cutter.
Fig 15.
The same procedure is repeated, performing the appropriate number of sutures as needed to repair the medial meniscal tear. Green arrows point to the several appropriate sutures performed to repair the medial meniscal tear. Red arrows point to the reduced tear.
After Surgery
The patient is discharged the day after the surgery non-weightbearing and with no flexion for 4 weeks, followed by partial weightbearing and knee flexion up to 90° for another 2 weeks. Full weightbearing and full knee flexion are allowed at 6 weeks after surgery.
Discussion
Tying the final knot on the outer surface of the capsule has reported complications such as (1) catching sensory nerves like the saphenous nerve under the knot with a resultant focal sensory loss and paresthesia and (2) pain under the skin because of irritation from the knot.11
The advantages of the meniscus-side-knot-tying technique (Table 1) over the capsular-side-knot-tying technique in arthroscopic outside-in meniscal repair are many: (1) avoiding catching sensory nerves under the knot thus avoiding postoperative focal sensory loss and paresthesia; (2) avoiding pain under the skin from irritation of the knot; (3) the tension of the sliding knot and the subsequent half hitches can be accurately monitored under vision; (4) no skin incisions needed; (5) in capsular-side-knot-tying technique, there is a possibility of cutting the suture limbs while performing a skin incision between the 2 needle holes; and (6) the ability to suture meniscal tears in the mobile parts of the meniscus without fixing them to the capsule like tears in the anterior horn of the lateral meniscus.
Table 1.
Advantages of the Meniscus-Side-Knot-Tying Technique in Arthroscopic Outside-In Meniscal Repair
| Avoid catching sensory nerves under the knot, thus avoiding postoperative focal sensory loss and paresthesia. |
| Avoid pain under the skin from irritation of the knot. |
| The tension of the sliding knot and the subsequent half hitches can be accurately monitored under vision. |
| No skin incisions are needed. |
| The surgeon is able to suture meniscal tears in the mobile parts of the meniscus without fixing them to the capsule, like tears in the anterior horn of the lateral meniscus. |
| In the capsular-side-knot-tying technique, there is a possibility of cutting the suture limbs while performing a skin incision between the 2 needle holes. |
Tying the knot on the outer surface of the capsule in outside-in technique can result in injury of sensory nerves such as the saphenous nerve when the knot is inadvertently tied around the nerve or its branches, resulting in focal sensory loss or paresthesia.2,11
Tying the knot on the outer surface of the capsule and performing subsequent several half hitches result in a bulky knot under the skin. This bulky knot will lead to pain because of skin irritation, and patients will often complain of pain at the knot site for a long period after surgery rather than anything else related to the surgery. This problem is totally avoided when shifting to tying the knot on the outer surface of the meniscus.
Tension of the sliding knot and the subsequent half hitches can be easily monitored under vision in the meniscus-side-knot-tying technique. However, this is not possible in the capsular-side-knot-tying technique because the knot is hidden deeply under the subcutaneous tissue, especially in obese patients.
In the meniscus-side-knot-tying technique, there is no need to perform any skin incisions, whereas in the capsular-side-knot-tying technique, a small skin incision will very likely need to be performed. In addition, performing this small skin incision might sometimes lead to cutting of the suture treads before tying the sliding knot.
The outside-in meniscal repair technique is the procedure of choice for repairing anterior horn meniscal tears. And, because the anterior horn of the lateral meniscus is mobile and moves back and forth with knee flexion and extension,12, 13, 14, 15 repairing a meniscal tear in the anterior horn of the lateral meniscus and fixing it to the anterior capsule using the capsular-side-knot-tying technique will interfere with this normal motion. Thus the meniscus-side-knot-tying technique will be the procedure of choice for repairing anterior horn lateral meniscal tears because it will not fix the anterior horn of the lateral meniscus to the anterior capsule, allowing it to move normally back and forth.
Limitations and risks (Table 2) of the meniscus-side-knot-tying technique are as follows: (1) not applicable for posterior meniscal tears; (2) special instrumentation needed, such as a suture retriever and knot-pusher-suture-cutter, which might not be available in all settings; (3) overtightening of the sliding knot and the subsequent half hitches using the knot-pusher, which might lead to iatrogenic injury of the meniscus, especially in poor-quality and degenerated menisci; and (4) the surgeon must be familiar and trained to do a sliding arthroscopic knot.
Table 2.
Limitations and Risks of the Meniscus-Side-Knot-Tying-Technique
| Not applicable for posterior meniscal tears. |
| Need special instrumentation such as suture retriever and knot-pusher-suture-cutter, which might not be available in all settings. |
| Overtightening of the sliding knot and the subsequent half hitches using the knot-pusher might lead to iatrogenic injury of the meniscus, especially in poor-quality and degenerated menisci. |
| Surgeon must be familiar with and trained to do a sliding arthroscopic knot. |
Disclosure
The author reports no conflicts of interest in the authorship and publication of this article. Full ICMJE author disclosure forms are available for this article online, as supplementary material.
Supplementary Data
Meniscus-side-knot-tying technique in arthroscopic outside-in meniscal repair has several advantages over the capsular-side-knot-tying: avoiding catching nerves under the knot; avoiding pain under the skin because of irritation from the knot; the tension of the sliding knot and the subsequent half hitches can be monitored accurately under vision; no skin incisions needed; the ability to suture tears in mobile parts of the meniscus without fixing them to the capsule like tears in the anterior horn of the lateral meniscus; and no possibility of cutting the suture limbs while performing the skin incision between the 2 needle holes.
References
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Associated Data
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Supplementary Materials
Meniscus-side-knot-tying technique in arthroscopic outside-in meniscal repair has several advantages over the capsular-side-knot-tying: avoiding catching nerves under the knot; avoiding pain under the skin because of irritation from the knot; the tension of the sliding knot and the subsequent half hitches can be monitored accurately under vision; no skin incisions needed; the ability to suture tears in mobile parts of the meniscus without fixing them to the capsule like tears in the anterior horn of the lateral meniscus; and no possibility of cutting the suture limbs while performing the skin incision between the 2 needle holes.
Meniscus-side-knot-tying technique in arthroscopic outside-in meniscal repair has several advantages over the capsular-side-knot-tying: avoiding catching nerves under the knot; avoiding pain under the skin because of irritation from the knot; the tension of the sliding knot and the subsequent half hitches can be monitored accurately under vision; no skin incisions needed; the ability to suture tears in mobile parts of the meniscus without fixing them to the capsule like tears in the anterior horn of the lateral meniscus; and no possibility of cutting the suture limbs while performing the skin incision between the 2 needle holes.