CA2035201A1

CA2035201A1 - Method and instruments for acl reconstruction

Info

Publication number: CA2035201A1
Application number: CA002035201A
Authority: CA
Inventors: Thomas D. Rosenberg
Original assignee: Acufex Microsurgical Inc
Current assignee: Smith and Nephew Inc
Priority date: 1990-01-31
Filing date: 1991-01-29
Publication date: 1991-08-01
Also published as: US5139520A; EP0440991A1; AU7010691A; FI910443A0; KR910014094A; US5374269A; FI910443A

Abstract

METHOD AND INSTRUMENTS FOR ACL RECONSTRUCTION

ABSTRACT

An improved method of reconstructing a torn anterior cruciate ligament (ACL) is disclosed. Unique instruments and systems for use with the method are also disclosed. The knee joint is inspected arthroscopically to confirm the rupture and possibly take care of other defects. The patellar tendon or semitendinosus tendon is harvested from the patient for the graft (if either is going to be used for the reconstruction), or another ACL substitute is obtained.
The graft is prepared for implanting. Notchplasty is generally performed to expand the intercondylar notch.
The tibial attachment site of the ACL is determined and a tibial tunnel is drilled over a K-wire from the front face of the tibia to the attachment site using a drill guide system. Preferably, the tibial tunnel starts at a point 20-25 mm below the knee joint. An optimal site for drilling the femoral tunnel is determined through use of a suture anchor and isometer. The suture anchor is a threaded peg which is positioned by a hand-held cannulated driver. A pilot hole is formed preferably with a unique K-wire device having means thereon for limiting the depth of the hole. Once the isometric point has been determined, a closed-end tunnel (or "socket") is drilled into the femur at that point. The hole is drilled using a new drill bit having a small shank, an abbreviated drilling head, and a smooth transition portion between the shank and head; this drill bit prevents damage to the posterior cruciate ligament. The graft is implanted through the osseous tunnel with one end being secured in the closed-end femoral tunnel and the other end to the front of the tibia adjacent to the tibial tunnel. Semitendinosus tendon grafts are prepared in bundles with elongated sutures stitched at the ends. A suture passing channel is formed through the femur from the closed-end femoral tunnel and the graft sutures are passed through it and connected to the lateral face of the femur by a button.
The graft sutures are affixed at the other end of the graft to a post or screw secured in the tibia.
Patellar tendons can be affixed at one end in the closed-end femoral tunnel with an interference screw, or, alternately, sutures passed through a passing channel and affixed to a button on the femur. The other end of the patellar tendon grafts are secured by being stapled or otherwise securely affixed to the tibia.

Description

1,521-00 2035201 METHOD AND INSTRUMENTS FOR ACL RECONSTRUCTION

TECHNICAL FIELD

The present invention relates to an improved method for reconstruction of a torn anterior cruciate ligament ("ACL") using endoscopic techniques, as well as new and improved instruments for use with the method.

BACKGROUND ART

Damaged ligaments, cartilage and tendons in joints are not an unco~on occurrence, particularly with today's emphasis on physical activity and conditioning. One of the joints which requires particular 5~ill and presents particular dif~iculties in repairing i8 the knee ~oint.

Numerous improvements in repairing damage to knee joints have been made over the years, and some of the major advances involve endoscopic techniques and arthroscopic procedures. Arthroscopic surgery is particularly useful in excising or repairing damaged knee cartilage.

, ~ . , .,.,., , , .. .. , ~ -. . - . .

., : , , ., . , , Endoscopic techniques have also been developed for use in repair and reconstruction of damaged anterior cruciate ligaments (ACL) and posterior cruciate liga-ments (PCL). When the ACL in particular has ruptured and is nonrepairable, it i8 ugually replaced in young adults and the knee reconstructed through use of grafts (biological or synthetic). Some known methods and techniques which have been used to repair and replace ACL ruptures with graft~ are discussed, ~or example, in Moore U.S. Patent No.
4,773,417, Goble U.S. Patent No. 4,772,286 and an article by Goble entitled "Fluoroarthroscopic Allograft Anterior Cruciate Reconstruction", Technigues Orthop.
1988 2(4): 65-73.

The function of the real cruciate ligaments is complicated. The ACL and PCL are three-dimensional structures with broad attachments and a continuum of fibers. These fibers are of different lengths, have different attachment sites, and are under different tensions. Although many current ~ubstitutes for cruciate ligaments have not duplicated the complex orientation and operation of nor~al ACLs, they operate the best and mimic ~he normal ACL operation the best when they are placed isometrically. "Isometrically"
positioned means that the length of the substitute ligament will not change during annular movement of the tibia relative to the femur; the distance between the affixed ends of the ligament remains a constant.
~sometric placement maximizes the number of fibers that can be taut throughout the range of motion of the knee - and allows for early knee motion without generating high ligament strains.

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20352~

Correct iSOmQtriC positioning of the ACL
graft thus i8 an important factor for a successful operation. Correct isometric placement reproduces corresponding femoral and tibial anatomic attachment sites and will allow an ACL graft to mimic the normal ACL. Isometric-ally placed grafts provide the most stable knees. Non-isometric graft placement can result in plastic deforma-tion of the ACL substitute, postoperative laxity, abnormal kinematics, or failure of fixation.

The importance o~ accurate placement of an ACL substitute is shown by the fact that graft placements sometimes only several millimeters apart produce signi~-icantly dif~erent strains in the cruciate substitute. A placement o~ the ACL origin or insertion which is too anteriorly placed in the knee joint results in a liga-ment th~t is taut in flexion, but lax in extension. Posterior placement causes the ligament to be taut in extension, but lax in flexion.
Only isometrlc placement provides stability throughout the range of motion.

25It is an object of the present invention to provide an improved method using endoscopic techniques for reconstruction of ACLs. It is a further object to provide i~ometric placements of ACL substitutes, and isometric placements w~ich are objectively accurate and reproducible.

It is still a further object of the invention - to provide an ACL replacement which is minimally inva-sive in order to minimize trauma and facilitate . -. . , .: . ~

. ,' ' . ~ ,' ' ' ' ': ~
: :
,: . . ' .' : ' faster patient healing and rehabilitation. It i~
another object to provide a method of ACL
reconstruction which preferably use~ biologlcal gra~ts from the patient and which provides similar and beneficial results whether patellar tendon grafts, semitendinosus tendon grafts, or other ACL substitutes are used.

It is still another ob~ect of the present invention to provids a new and improved method for assuring isomatric placement of the ACL graftt and for minimizing the chance of PCL damage.

Further ob~ects of the invention include development and use of improved instruments for ACL
operations which help assure proper isometric graft placement, help prevent damage to the PCL, and provide an improved method for ACL reconstruction.

DISC~OSURE OF INVENTION

The abovs and other ob~ects of the invention are met by the inventive method o~ ACL reconstruction and instrumentation which are disclosed and claimed in this application.

For the improved method, the knee joint is inspected arthroscopically to confirm the rupture and possibly ~ake care of other defects. The patellar tendon or semitendinosus tendon i8 harvested from the patient for use as the graft, or another ACL ~ubstitute is obtained. The graft another prepared for later implantation. Semitendinosus tendon grafts are .. . ; , , .
.
'~ :" , ' 203~201 preferably dlv~ded into sections snd the sections are formed together into a bundle. Elongated suture~ ara stitched at the ends o~ the graft bundles for u~e in implanting the graft and affixing it in place. For patellar tendon grafts, the bone plugs (or "blocks") at each end are shaped and sized for later use.

The torn ACL 8tump8 are studled and partially removed if necessary. Notchplasty is preferably per-formed to expand the intercondylar not~h. ~oth manual and powered instrument~ can be used for this procedure.

The tibial attachment site ~or the ACL gra~t is determined. A tibial drill guide mechanis~ guides a K-wire from a point 20-25 mm below the knee joint to the former ACL attachment site. A point on the guide mechanism is placed on the former site and a drill sleeve ("or bullet") is forced into the bone at the requisite position for drilling the tibial tunnel. A
cannulated drill bit i~ overdrilled on the K-wire formlng the tunn01.

The site for drilling the tunnel in ths femur i8 deter~ined isometrically. A proposed site i5 se-lected and tested for isometry. A pilot hole of a pre-specified size and depth is formed at that site.
The pilot hole can be formed with a K-wire drill bit ~0 having graduated markings thereon, or preferably a K-wire having a reduced-size diameter tip and shoulder thereon. ~ threaded peg wi~h an elongated suture attached is then screwed and anchored in place in the pilot hole at the proposed site. A hand held .: '' . . ~' ., ' ~' ' : .
. - ' ,: ' ' . '' ' ' : . ~ ' ' :
.

203~201 cannulated driver with an elongated sleeve and suture retention member are uti-lized. The threaded peg and sleeva end have mating cross-sectional sizes and shapes so the peg can be screwed in with the driver.

Once the suture anchor i8 installed, the sutures are passed through a centering plug and through the isometer and affixed tightly in place on the back of the isometer. The isometer is unlocked and readings are taken during movement of 'he knee.

If the proposed site is isometric, then a K-wire is inserted as a guide pin and a closed-end tunnel i6 drilled into the femur at that site. If the proposed site i~ not isometric, then the te~t i~
.!~ repeated at another site until isometry i8 reached.
The femoral tunnel i8 drilled using a drill bit with an abbreviated drill head, a reduced sized shank, and a smooth transi-tion area between the head and shank.
This drill prevents damage to the posterior cruciate ligament and permits ease of removal from the drilling site.

The edges of the tibial and femoral tunnels are chamfered with a rasp to prevent abrasion and possible damage to the new graft.

The graft is implanted with one end secured in the closed-end femoral tunnel and the other ~end secured to the tibia adjacent to the tibial tunnel.
With a patDllar tendon graft, the bone plug on the - leading end is locked in place in the femoral tunnel preferably with a unique interference screw. The bone .

-` 2035201 block on the trailing end is secured by bone staple~ or the like in a trough or channel formed in the tibia below the tunnel entrance. Alternately, elongated sutures can be ~titched onto the bone ~lock on the leading end of the graft and then passed through a suture passing channel formed in the femur. The sutures ara secured to a button on the lateral race of the femur.
With a semitendinosus tendon graft, the bundles with elongated sutures are passed or pulled through the o~seous tunnels. A suture passing channel is preferably formed from the closed-end femoral tunnel to the lateral face of the femur and the sutures are passed through it with a pull-through wir~. Once the leading end of the gra~t is positionsd in the socket, the suture~ are tightly af~ixed to a button. The ~utures at the trailing end of the graft are affixed to a screw or post positioned on the tibia ad~acent the entrance to the tibial tunnel. The post has a washer under its head to assure a tight connection between the post and sutures.

BRIEF DESCRIPTION OF DRAWINGS

FIGURES 1 and 2 are schematic perspective views of the harvesting of the ~emitendinosus tendon for use as an ACL replacement in accordance with the present inventlon;

FIGURE 3 illustrates a representativa semiten-dinosus tendon prepared for use as an ACL graft $n accordance with the present invention;

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203~2~1 FIGURE 4 illustrates a patellar tendon har-vested and ready for use as an ACL graft in accordance with an al ernate embodiment of the present invention;

FIGURE 5 is a schematic perspective view of the "notchplasty" procedural step for ACL
reconstruction in accordance with the pre~ent invention:

FIGURES 6 and 7 illustrate an endoscopic tibia drill guide and it use in accordance with the present invention;
FIGURE 8 illustrates the formation of the tibial tunnel using a cannulated drill bit over-drilling a K-wire pin;

20FIGURES 9A and 9B show various point3 ~or location o~ the femoral attachment site;

FIGURES lOA and lOB illustrate the mark~ng and drilling of the proposed femoral attachment site and the configuration of a K-wire drill which can be used for thi~ step in the procedure;

FIGURES 11-14 depict the anchor and driver system used as part of the procedure for iqometrically determining the femoral attachment 3ite for the graft;

FIGURES 15A and 16 depict use of an isometer in isometrically determining the femoral attachment ~ite;

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g FIGURE 15B is a cross-sectional view of the isometer shown in Figures 15A and 16:

FIGU~E 17 illustrates the drilling of the closed-end femoral tunnel in accordance wit~ the present invention;

FIGU~E 18 depicts the preferred drill bit or reamer used to form the femoral tunnel in accordance with the present invention;

FIGURES 19, 20, 21 and 22 illustrate position-ing and securing of patellar tendon grafts in accordance with one embodiment of the present invention;
~, .
FIGURE 2lA illustrates an interference screw used to secure the patellar tendon graft in the femoral 20 socket;

FIGURE 23 illustrates an alternate method for securing a patellar tendon gra~t in place; ~:

FIGURE 24 illustrates one step in the proce-dure for securing semitendinosu~ grafts in accordance with another embodiment of the present invention: and FIGURE 25 depicts the po~itionlng and securing of semitendinosus graft~ in accordance with the present invention.

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.:

BEST MODE FOR CARRYING OUT THE INVENTION

For a knee reconstruction involving a torn anterior cruciate ligament (ACL), the procedure beg~ns with a general anesthe~ia being administrated to the patient. The patient is positioned supine on the operating table. The affected limb i~ secured in a thigh holder after a tourniquet i8 put in place. The surgical 8ite ig prepped and draped with a sterile seal.

Often a suitable autoqraph i8 harve~ted and the anterior tibea cortex exposed before the prepared knee is examined by arthroscopic procedure3. Standard anterola~eral and an~eromedial portals are made for the diagnostic arthroscopy. The fat pad i5 pushed away from the area by distension of the knee. Any observed meniscal damage, osteophyte and unstable ~olnt surface~
are appropriately treated by standard arthroscopic techniques and the status of the cruciate ligaments is confirmed.

The graft harve ting step used in the pro edure depends on the type of ACL substitute that is to be utilized. If a semitendlnosus graft of the patient is to be utilized, an incision 40 is made over the pes anserinus in line with the fibers of the sartorius (Figure 1). The sartorius is split (opened) to reveal the semitendinosus and gracilis tendons. The semitendi-nosus ~endon 42 ls isolated from the muscle and detached from the tibia 43. Tension is placed on the tendon by the index finger of one hand while it is being isolated and detached. The detached end of the ,,,,' ,- : : . ' . ........................ . .

: :- . . ~ .

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tendon is pre-pared for grasping by lnstallation of sutures using a No. 2 Ticron ~uture and a tendon needle. Pxeferably, a serieR of six whip stitche~ 44 are placed along each side o~ the loose end o~ the tendon (Figure 2). The multilevel clasping sutures provide an excellent grasp-ing fixation of the ~uture tendon ~unction.

lo The semitendino~us tendon i8 removed by a tendon stripper 46, preferably a closed-end tendon stripper made by Acufex Microsurgical, Inc., Norwood, Massachusett~ (Part No. 013550). After the ends of the suture and 1008e end of the tendon are threaded through the tendon stripper, the tendon is grasped and held in tension manually at the ends 48 of the sutures 44. ~he stripper is slowly advanced up the length of the tendon until it is completely separated from the femur 36 and delivered. The stripper circumferentially divide~ the tendon using it~ sharp round leading edge 50. With this procedure, the length of the tendon is maximized.

The semitendinosus tendon i~ then prepared for later use as the ACL substitute. It i~ measured and divided into several segments or sections (Figure 3). Usually individual segments 52 and sometimes doubled over segments 54 are utillzed. No. 2 Ticron sutures 56 are attached to the ends of the graft sections for use in pulling the composite graft through the osseous tunnel and securing it at each end (as later explained). The loose ends 58 of the suture3 provide satisfactory grasping fixation of the individual sections of ~he compo~ite graft 55. The graft segments 52 and 54 are preferably approximately .,., ~ , 203~201 6-8 cm in length and as a group or bundle 55 are about 8-11 mm in diameter.

If a patellar tendon gra~t 60 (Flgure 4) i8 to be utilized, then it is removed ~rom the tibia and kneecap. An incision i8 made medial to the infra-patellar tendon and the patellar tendon ls harvested using conventional techniques. Small blocks ("plugs"~ of bones 62 and 64 are taken and retained at each end of the tendon to ald in latsr securing th~
graft in the knee. The blocks of bone 62, 64 are sized using 1 mm incremental sizing tube to obtain clo~e conformity between the graft 8ize and ths tunnel size.
This i8 nece~sary for optimal healing to occur. Once size is determined, the corresponding drill bit or bit~
are selected for later use in forming the tunnel in th~
tibea and the socket in the femur.

Although the present inven~ive method i~
preferably used with a sem~tendlnosu~ tendon graft or patellar tendon graf~, it is understood that the inven-tion can be used to assure isometric placement of ACL replacements and a beneficial and advantageous ACL
reconstruction utilizing any o~ the known grafts and ACL substitutes. Known ACL substitutes include autogenou3 tendons, frozen and lyophilized tendon allografts, and a variety of synthetic materials.

If, for example, another type of ACL graft is to be utilized instead of the semitendinosus or patellar tendons~ it should be prepared in a ~imilar manner. No. 2 Ticron su~ure~ are attached at the ends o~ the graft in some conventional manner to aid in - , ~ :-: ::

" 2035201 grasping, manipu-lating and securing the graft in place. Incremen~al sizing tubes are used to size the graft and select the appropriate drills for forming the tunnel. Installation and attachment o~ the graft to the femur and tlbia are the same as that which will be described below relative to placement and attachment o~
a semitendino3us tendon.

10After confirming a rupture of the ACL and taking steps to prepare the appropriate graft, a portion of the synovium and ligament stump i5 excised with conventional instrumentation to facilitate visibility during implantation o~ the gra~t. Care should be taken at thls point to protect the PCL and avoid in~ury to it and its synovium.
~, Selective lateral and superior expansion "notchplasty" of the intercondylar notch 74 i9 achieved using, initially, appropriate gouges and then, a motor-ized cutter and abrader 70. Part of this conventional procedure is shown in Figure 5. During notchplasty, the 25 arthroscopic viewing is generally positioned ~rom the anterolateral portal. The motorized cutter and abrader 70 are inserted through the anteromedial portal. The motor$zed cutter (not ~hown) is used to remove the soft ti~sue. The rotating abrader tip 72 is used to remove the bone in the intercondylar notch 74 in the femur 36. The notchplasty i~ performed to increase visibility to the proposed femoral attachmen~ site and to avoid impingement of the ACL substitute during use after it is implanted. Again, care should be taken during this procedure to avoid damaging the PCL.

. . ~ --:: :
- ~ - . : ~ . . . :
, , , 203~2Ql After the notchplasty, the tibial tunnel i8 formed. The placement of the portion of the osseous tunnel in the tibia, as well as the placement of the portion of the tunnel in the femur is important. The two tunnels should be formed 80 that they enter the joint at the proper anatomic attachment points. These points are preferably on the knee ~oint ~urfaces where the original ACL was attached.
The preferred manner of forming the tibial tunnel is shown in Figures 6-8. A vertical incision 80 (Figure 6) is made ~edial to the infrapatellar tendon, and approximately 2 cm distal to the ~oint line 81.
The periosteum i incised and elevated exposing the tibial cortex. A unique drill guide instrument 82 is used to select the proper tibial attachm~nt and tunnel drilling sites. The guide 82 has a handle 84, a collar 86 and a roughly semicircular shaped tibia point selector member 88. The member 88 has an ai~er point 90 at the angle near th~ tip and has a bent portion 92 to prevent contact with the femur and the patella. The aimer point 90 is posi~ioned endoscopically on the appropriate tibial anatomic attachment site. The attachment ~ite i~ identified by probing through the anteromedial portal with the aimer polnt 90. The point 90 i~ positioned against the bone and the guide 82 is then manually held ~irmly in position.

Once the aimer point 90 is positioned in place, a drill sleeve (or "bullet") 94 is placed through the collar 86. The drill sleeve is hollow, having a passageway for placement therethrough of a sharp pointed 3/32" K-wire pin 96. The front end 98 of :

~03~201 the bullet ~4 has a sharp tri-point and the rear end has a knob 100 for ease of grasping and manipulation.
Due to the shape and structure of the instrument 82, the collar 86 is positioned optimally 80 that the bullet 94 will contact the tibia 43 at a di~tance l'D'' 20-25 ~m below the joint line 81. Once the tri-point bullet g4 is positioned in place, it i8 then locked in place in that position in the collar 86 by a long lo threaded rod 102 which i~ operated by knob 104. The rod 102 is threaded ~hrough a threaded opening (not shown) in the collar 86 and makes contact with the bullet 94. When the rod is rotated by the knob 104, it forces tha bullet 94 into firm non-slipping engagement with the inner wall of the collar 86 holding the two members firmly locked togeth-er.
- .~3 Once the drill guida 82 and bullet 94 are firmly set in place, the K-wire 96 18 ~assed through the bullet 94 and drilled into and substantially throuqh the tibia u ing a conventional surgical motorized drill. The ~ullet 94 i~ then relea~ed from the collar 86 and removed from the guido 82 leaving the K-wire in place. The drill guide 82 i~ al50 removed.
The K-wire pin ~ then advanced (by hitting it with a mallet or the like) to a~sure that its position in the tibial stump is appropriate, and al80 to assure that the direction of the pin i5 correct in the vlcinity of the femoral anatomic at~achment point. The position and direction are viewed arthrGscopically.

A cannulated drill bit 110 is selected corre-sponding to the size of ~e graft and placed over the X-wire g6 (Figure 8). An 8-11 mm cannulated drill ; ,, ~ , 203~201 b~t is selected if a semitendinosus tendon i~ being used as the graft. The tibial tunnel 112 for the graft is then drilled through the tibia uslng a conventional surgical motorized drill 114 and using the K-wire 96 as a guide. Where possible, the stump fiber~ of the original ACL are preserved as a biological covering for the graft. The edges at the two ends of the tunnel are smoothed and ~eveled using conventional rasp-type chamfering instru-ments in order to prevent later abrasion and damage to the graft.

~ s shown, the use of the drill guide instru-ment 82 allows the surgeon to drill an anatomic tunnel 112 from a point ~ust 2 to 2.5 cm di~tal to the ~oint line and which accurately and reproducibly enters ~, the ~oint at the anatomic attachment ~ite. The instrument 82 ensures highly accurate, reproducible guide wire placement, whilo enabling the surgeon to create femoral and tibial tunnels with a reduced divergence angle and close to a straight lLne. The drill guide, as with all of the surgical in~truments preferred ~or use in the specified operation, i8 made from a autoclavical metal material, pre~erably stainless steel. A preferred drill guide 5y8tem iS
available from Acufex Microsurgical, Inc., entitled "Endoscopic Drill Guide System" (Part No. 013650).

once the tibial tunnel 112 is completed, the next step involves selecting the proper site in the femur 36 for the remainder of the os~eous tunnel. As mentioned earlier, selection o~ the appropriate isomet-ric point is important. As illustrated in Figures 9A and 9B, point A is proximal and high in the : ', - ' :

' ' ', :.' ', ' ~ ' ' ~

notch 74 and typically demonstrate~ an isometry pattern which mimics the normal ACL. Point B ls distal (anterior as viewed arthroscopically) and generally demonstrates unaccept-able elongation in flexion.
Point C is lateral and posterior in the nstch 74 and generally demonstrates excessive strain in extension.

Once the suggested femoral site i8 selected, lt i9 tested isometrically to determlne if it is the best pocsibla sita. This test procedure is shown in Figures lOA-16. A K-wire 9 6 i8 lnserted through the tibial tunnel 112 and its point is used to make a small pilot hole 120 in the intercondylar notch 74 at the proposed femoral attachment site. Due to the size of the tunnel 112 compared with the size of the K-wire, it ~, i8 possible to manipulate and move the K-wire in order to ~eleat the most appropriate point to make the hole 120.
Working with the knea flexed at a 90 angle, the pilot hole 120 at the proposed isometric site 18 drilled to an appropriate depth for attachment of an isometric anchor. A surgical motorized drill is used 2g to advance the K-wire a preselected distance into the femur to allow easy attachment of the anchor. In order to asqure that the K-wire is not advanced too far, a graduated K-wire (that ~s a K-wire with millimeter markings on it) or preferably a stepped K-wire (as shown in Figure lOB) can be utilized. The ~tepped K-wire drill 160 has a reduced diametsr end 162 ~eparated from the main shaft 164 by a shoulder 166.
- Preferably, the diameter of the main sha~t 164 is 0.118 inches, the diameter of the end 162 is o.oal inche~, , - ~
. ~ . .

: - .. . ........................ .
"- , . ' , : ' ~ , .. .
- , ~ -and the length of the pilot K-wire from the shoulder 166 to the tip i9 O. 250 inches- The shoulder is used to prevent the X-wire from being advanced too far into the femur since it limit~ the depth o~ the drllled opening. For proper attachment of an anchor, the hole 120 in the femur should be drilled to a depth o~
approximately 6 mm.

10Next, a small suture anchor i8 attached to the femur at the ~elected point in the drilled hole 120. The anchor 130 consist~ of a threaded peg 132 connected to No. 2 suture 134 through an eyelet 136 (see Figures 11-13). A unique hand held cannulated 15driver 140 is used to deliver the anchor 130 to the proposed site and fasten it in place. The driver is cannulated having an elongated hollow sleeve 142 and a hollow handle 144. The handle has a tie button or suture affixation post 146 on it. The suture 134 is threaded down through the driver 140 by use of a conventional suture r~triever 150 (Figure 11), pre~erably the Acufex SuturQ Retriever by Acufex Microsurgical, Inc. The suture 134 i8 used to pull the threaded anchor peg 132 tightly into the end ~43 of the driver sleeve 142 and the suture is then secured tightly in place ~y wrapping it around the post 146.

As shown in Figure 13, the rear end of the threaded peg 132 has a non-circular cross-section (preferably a hexagonal shape~ and the open top end 143 of the sleeva 142 has a corresponding mating cross-sectional size and shapa. In this manner, when -the anchor 130 is seated firmly in place in the driver 140, rotation and manipulation of the driver 140 will ~5 - , .~ . ' ~ .
..;
.
.. . - , , . . .. -.

203~201 have an identlcal corresponding effect on the anchor 130. The preferred anchors and drivers for use with the present invention are the "Isotac" anchors and "Isotac" drivers marketed by Acufex Microsurgical, Inc.
The "Isotac" anchor (threaded peg) preferably ha~ an outer diameter of 0.093 inches and fit~ tightly into the pilot hole.

After the driver 140 is loaded with the anchor 130 as shown in Figure 12, the unit i8 passed through the tibial tunnel 112, as shown in Figure 14, and the anchor peg 132 is set in place in the opening 120 drilled in the femur. The driver 140 i5 manually rotated which, in turn, screw~ the threaded peg 132 into ths bone until it i~ securely ~ixed in place.
Viewing arthroscopically, the anchor iB rotated into the femur until ~he end 143 of the driver sleeve 142 abuts the femoral surface. After the anchor 130 is set in place, the driver 140 i5 removed and set aside, leaving the suture 134 extending through the tunnel.

The 3uture 134 i~ thr~aded ~hr~ugh a centering plug 170 and the plug i8 then inserted into the tibial tunnel 112 (Figures 15A and 16). A suture passer or retriever can be used if desired to thread the suture through the guide. The suture 134 is also passed through a spring loaded strain gauge (or isometer) 180. (I~ desired, the suture can be passed through the guide 170 and isometer 180 in one step).

The isometer 180 has a front end 182 which is adapted to abut and mate with the guide 170, a housing 184 and a plunger member 186, as best shown in Figure :

~ , .
: - ,' '.
:
, . , 15B. The plunger 186 fit~ within the hou~ing 184 ln a sliding telescopic relatlonship. The lnternal end 188 of the plunger 186 i8 connected to a coll spring 190.
S The coll spring, in turn, is connected to the lnslde of the housing. The end 188 also has a locking post 192 which is adapted to slide along 810t 194 or be locked in position in a bayonet or ~'J"-shaped slot 196. The spring 190 biases the member 186 relative to the hous-ing. The plunger 186 also has a suture anchoring member 198 at its outer or external end.

A scale 200 in millimeters i~ arranged along the edge of the slot 194 80 readings can be made of the position of the post 192 relative to it. Pre~erably, the center of the scale at the entrance to the J-shaped slot 196 is set at "zero" so that positive and negative strain gauge readings from the zero point can be read in millimeter~ depend~ng on the movement of the post 192 during operation of the isometer 180.

With the isometer 180 locked to the zero position (i.e. with the post 192 posltioned in the 810t 196), th~ patient's knee is pos~tioned at approximately 45 ~lexion. The front end 182 of the isometer is abutted against the guide 170 and ~he slack is taken up in the suture 134. The suture 134 is securely posi-tioned and tightened around the member 198 at the end of the plunger 186. Thi~ is shown in Figure 16.

To check on the isometry of the positioning of the proposed femoral attachment si~e, the isometer is unlocked and the knee is manually taken through the :
,~ ' ':

203~201 range o~ motion permltted by the operating site. As the knee is moved and the suture afXected thereby, the plunger i9 translated relative to the housing in a proportional manner. The movemen~ o~ the po~t along the slot provide~ a reading o~ the strain on the suture.

An optimal reading reveals a 0-1 mm change in length while flexing and a 2-3 mm elongation (tighten-ing) in terminal extension. A 2-3 mm elongation pattern caused by interior rotation o~ the tibia i~ also pre-ferred. If readings within the6e ranges are achieved, then ths correct femoral attachment site has been determined and ths hole 120 i~
at the appropriate position. In rare circu~stance~, such as a variation in surgical ~echnique (i.e. tibia site selection), failure o~ s2condary restraint, or interference by the PCL, the preferred readings may be affected. However, except for these rare circumstances, if the readings are not within these ranges, then another proposed site is selected and the isomatric test repeated. This involves drilling another hole with a K-wire, attaching another suture anchor ln the new hole with the cannulated driver, and repeating the testing process with the centering plug and isometer. ~, once isometry is confirmed and the appropriate femoral site selected, the driver 140 is used to unscrew and remove the anchor peg 132. The anchor 130 i8 then discarded. ~he knee joint is returned to the 90 position and the sharp K-wire 96 is directed through the tibial tunnel 112 and into the - ' . ~ ' ' ~............. : - ~

hole 120 in the femur. The K-wire is then drilled into the femur sufficiently to hold it in place and act as the drill guide for forming the closed-end femoral tunnel.

The K-wire i8 over-drilled with a cannulated drill bit or reamer. Thls i9 shown in Figure 17. The preferred drill bit or reamer 210, which i shown in Figures 17 and 18, has an abbreviated (shortened length of approximately 7 mm) drilling head 214, and a reduced sized shank 212 (5-6 mm) which is smaller in diameter than the drilling head 214. The shank i~ gradually 15~loped to the head 214 along annular surface 216 to make a smooth tran ition and prevent ~nagging or damage to the PCL and tibial tunnel when the reamer 210 i~
manipu-lated in the knee ~oint and sventually removed from the tibial tunnel. The 410ped surface 216 permits easy removal of the reamer from the knee ~oint. The reduced diameter shank 212 also importantly allows variation of placement of the femoral drilling site.

~ A closed end tunnel or socket 220, preferably about 2-2.5 cm in length, i~ drilled into the femur by the rea~er 210 after ~he rea~er has passed beyond the PCL. Th~ depth of the tunnel i8 deter~ined by noting calibration~ on the reamer 210. A tunnel 2.5 cm in depth i~ ~ufficient for semitendinosus grafts. If a patellar tendon is being used for the graft~ then the depth of the tunnel should be correlated to the length of the bone plug on the tendon.

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203~201 Once the femoral tunnel is drilled, the edge of the tunnel which opens into the knee ~oint i8 smoothed and chamfered with a conventional rasp. This prevents abrasion and potential damage to the graft.

Figure~ 19, 20, 21 and 22 ~how ~ha manner ln which patellar tendon grafts are positioned and secured into the osseous tunnels in accordance with one embodi-ment of the invention. (A typical patellar tendon graft is shown and described above with reference to Figure 4). The tendon 60 i5 harvested with bone plugs 62 and 64 at its ends.

A plunger instrument 230 ~ B used to introduce the leading bone plug 64 into th~ ~oint through the tibial tunnel 112 ~Figure 19). Once the bone plu~ ~4 has passed through the tibial tunnel and into the knee ~oint, an arthroscopic bone grasper 240 introduced through tha anteromedial portal is used to insert the bone plug into the closed-end femoral tunnel 220 (Figure 20). Alternately, a passing pin can be advanced fro~ the end of the femoral socket through to the lateral femoral cortex, piercing the ~uadriceps muscle and the subcutaneous and skin layers. The pin i8 used to pull sutures placed on the patellar bone block through the femoral socket and in turn pull ~he bone block into the socket.

Proximal fixation of the patellar tendon graft in the femoral tunnel 220 is preferably obtained by use of a 5.5 mm endoscopic screw 244 (Figures 21 and 21A). The screw 244 is introduced in~o the knee joint through the anteromedial portal and affixed in place .
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, 203~201 with an arthroscopic screw driver 246 or the like. The inter-ference screw abuts against the bone plug 64 and holds it firmly in place in the femoral tunnel. In order to prevent damage to the tendon, care should be taken not to turn the screw 244 into or against the tendon graft 60 during insertion. The preferred endoscopic interfer-ence screw i8 made by Acufex Microsurgical, Inc. The screw i~ self-tapping, has a cork-screw shaped tip for self-engagement, and the rows of threads after the first two rows are machined or smoothed 80 they will not da~age or cut the gra~t.
This screw is shown in Figure 2lA.

A trough 250 is prepared in the tibia below the opening of the tibial tunnel 112 for placement of the distal bone plug 62. ~ surgical staple 252 is used to affix the bone plug 62 into the trough 250.

once the graft ie secured in place, it is viewed arthroscopically and probed to confirm that the correct tension has been achieved. Tho knee i8 also moved through it3 normal range of motion to assure that impingement of the graft does not occur.
The above technique for ACL reconstruction uslng a patellar tendon graft uses a blind-hole tunnel in the femur and eliminates the necessity for a lateral incision in the thigh or top of the femur for position-ing or affixa~ion of the graft. This significantly reduces the trauma and scarring to the patient and facilitates fa~er healing and - rehabilitation.

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20352~1 Alternately, if another arfixation techn~que is preferred for the proximal end of the patellar tendon graft in the femur which does not utilize a screw, it is possible in accordance with the present invention, to utilize only a small lateral inc$sion above the femur and still avoid much o~ the trauma and scarring associ-ated with previously known ACL repair and reconstruction methods. For thi~ alternate method, the patellar tendon graft has No. 2 Ticron sutures 256 stitched onto the bone plug 64, as shown in Figure 23.
A passing channel 260 i8 also drilled (with a X-wire) past the closed end of the femoral tunnel 220 and through the lateral femur surface. A small lateral incision is made to expose the passing channel site in the lateral surface of the femur. A suture passing guide wire (not shown) is then positioned through the tibial and femoral tunnels and out through ths passing channel opening and used to pull the graft through the osseous ~unnel~ until the proximal bone plug 64 is seated firmly in the ~emoral tunnel. Passage of the gra~t i8 observed arthroscopically to conflr~ smooth advancement into the clo~ed-end femoral tunnel. The sutures 256 are secured at the lateral femoral cortex over a flxation button in a conventional manner.
Preferably, the button is a Delrin fixation button 2mm in thickness, 14-17 mm in diameter and with chamferred suture openinga to prevent damage to the sutures.
Distal fixation of bone plug 62 is obtained by stapling the bone plug into 2 trough as described above, or in any conventional manner.

In oxder to position and secure semi~endinosuq tendon grafts in place with suture .
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leaders (as shown in Flgure 3), a passing channel 260 i9 drilled past the closed-end of the femoral tunnel 220 with a K-wire dr~ll 96 (Figure 24). A small lateral incision i8 made and the lateral femoral cortex i5 exposed around the passing channel which extends through the femoral surface.

A suture passing guide (or pull through wire) is passed through the tibial and femor~l tunnels and out throu~h the later~l femoral cortex. The ends 58 o~
the No. 2 Ticron suture~ which are attached to the composite graft 55 are drawn through the knee and ~emur 36 with the pull through wires, thereby pulllng the semitendino-sus graft segments 52 and 54 into position in the o~seous tunnels. The passage of the bundled graft 55 is observed arthroscopically in order to make sure it ad-vances smoothly into the closed-end femoral tunnel. A probe can be u~ed to a~slst in the entry into the femoral tunnel.

The ends 58 of the sutures are secured at the lateral femoral cortex by use of a ~ixation button 270.
Again, a ~trong 2 mm thick Delrin button with chamferred suture openings i8 pr~ferred. Once ~he proximal end of the graft 55 has been 3eated in the femoral tunnel, the sutures are passed through openings in the button and tied off firmly in place. In order to secure the distal end of the semitendinosus graft, a fixation post (screw) 272 is attached to the tibia 1-2 cm below the entrance to ~he tibial tunnel 112. A hole is first drilled in the tibia at the point where t~e fixation post is to be positioned. The hole i~ drilled through the tibia ending in the strong bone layer on - :
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the opposite side of the tibia. The hole i8 tapped with screw threads and a small headed ~ixation screw i8 selected of the appropri-ate length.

After the fixation po8t 272 i5 screwed in most of the way (about 75-95%), the graft is pulled and ten-sioned distally through the osseous tunnels and the ends 58 of the distal sutures 56 are tied firmly around the post. The ~crew is then turnad down tightly until it is set firmly in the tibia. A washer 274 either attached to or positioned immediately under the head of the fixa~ion screw help~ hold the tied sutures in place when the screw is tightened.
Similar to the procedure mentioned above with ! respect to implantation o~ patellar grafts, the ~ecured semitendinosus tendon grafts are $nspected and probed arthroscopically to con~irm that the correct ten~ion and positioning has been achieved. The patlent's knee is also ~anually manipulated through its range of motion in order ~o asRure that graft impinge~ent does not occur. Any nece3sary decompres~ion o~ the intercondylar notch is carefully per~ormed if any points of impinge~ent on the graft are observed.

Finally, the wounds around the knee are closed, the tourn$quet is removed, and appropriate postoperativ2 care is followed.
While the best modes for carrying out the inventlon have been described in detail, those familiar with the art to which this invention relates will recognize various alternatives, ds~ign and embodlments . .

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203~201 for practicing the invention as defined by the following claims.

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Claims

1. A method of replacing a torn anterior cruciate ligament with a substitute graft member, the method comprising the steps of:
a) arthroscopically debriding the torn anterior cruciate ligament;
b) expanding the intercondylar notch by notchplasty;
c) determining on the medial tibial plateau the former attachment site of the anterior cruciate ligament;
d) drilling a passage in the tibia to said site;
e) determining the isometric point for drilling a passage from the intercondylar notch into the femur;
f) drilling through the tibia passage a closed-end passage into the femur at said isometric point;
g) inserting the substitute graft member through the passage in the tibia and into the passage in the femur;
h) securing the graft member to the femur;
and i) securing the graft member to the tibia.

2. The method as set forth in claim wherein the steps of determining the former attachment site of the anterior cruciate ligament and drilling the passage in the tibia comprise the further steps of:
positioning the point of a tibial drill guide means on said site;

positioning a drill sleeve means on the drill guide means, said drill sleeve means contacting the tibia;
advancing a K-wire through said drill sleeve means and into and through the tibia;
removing the drill sleeve means and drill guide means; and over-drilling the R-wire with cannulated drill means to form the passage in the tibia.

3. The method as set forth in claim wherein said graft member is a patellar tendon graft with a first bone block at one end and a second bone block at the other end, the first bone block being inserted and affixed in said passage in the femur and said second bone block being secured to the tibia.

4. A method of repairing a torn anterior cruciate ligament with a semitendinosus tendon graft, the method comprising the steps of:
a) harvesting a semitendinosus tendon for use as the graft;
b) expanding the intercondylar notch by notchplasty techniques;
c) determining the former attachment site of the anterior cruciate ligament to the tibia;
d) drilling a tunnel in the tibia to said site;
e) isometrically determining the point for creating a tunnel in the femur;
f) drilling through the tibia tunnel a tunnel in the femur to a pre-specified depth;

g) drilling a suture passage channel from the end of the femur tunnel through the femur;
h) securing the graft to the femur; and i) securing the graft to the tibia.

5. The method as set forth in claim 4 wherein the torn anterior cruciate ligament is removed, the semitendinosus tendon is divided into a bundle of members, stitching sutures are affixed on the ends of the bundle of members, one end of the bundle of members is positioned in the tunnel in the femur and wherein the graft is secured to the femur by passing the sutures on one end of the bundle of members through the suture passage channel and affixing the sutures to a button means, and the graft is secured to the tibia by affixing the sutures on one end of the bundle of members to a post means.

6. A method of isometrically determining he proper site for drilling a graft tunnel in the femur of a patient during repair and replacement of a ruptured knee ligament, said method comprising the steps of:
a) installing a suture anchor at a proposed site;
b) said suture anchor being installed with a driver handle and anchor peg, the peg having elongat-ed sutures thereon;
c) passing the sutures through a tunnel in the tibia and connecting them to an isometer; and d) testing the isometry of the proposed site by moving the knee through its range of motion and viewing the readings on the isometer scale.

7. A system for installing an anchor in a bone, the anchor having a threaded peg connected to at least one elongated suture, said system comprising:
a) a cannulated handle;
b) an elongated cannulated sleeve member connected to the handle;
c) a suture affixation means on the handle;
d) said anchor being positioned on the end of the sleeve member and being at least partially inserted therein;
e) said anchor and said end of the sleeve member having means for preventing rotation relative to one another; and f) said suture being passed through said sleeve and said handle seating said anchor and being secured to said suture affixation means.

8. A drill for forming a passageway in a bone, said drill comprising a drilling head, a shank of smaller diameter than said drilling head, an annular portion smoothly connecting said head to said annular portion, and means for determining the depth of the drill into the passageway.

9. A K-wire drill for forming a pilot hole of predetermined depth in a bone, the K-wire having a main section, an end section, said end section having a diameter smaller than the diameter of the main section and having a pointed tip, and shoulder means separating said main section from said end section, said shoulder means restricting the drilling of the X-wire drill into the bone up to the shoulder means.

10. An endoscopic screw for securing a graft bone plug into a bone tunnel, the screw means having a cork-screw shaped tip and a series of thread means, the thread means having a first section of threads adjacent the tip and a second section of threads, said second section of threads having rounded edges to prevent damage to said graft.