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Patella tendon harvest for ACL reconstruction

    Overview

    Learn the Patella tendon harvest for ACL reconstruction surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Patella tendon harvest for ACL reconstruction surgical procedure.
    The ideal graft for ACL reconstruction should be widely available and easily procured. It should have mechanical properties equal to those of the native ligament and it should allow secure fixation to enable aggressive rehabilitation. It should also incorporate rapidly and have limited donor site mobility. It should have a low probability for disease transmission or immune rejection. It should also be inexpensive.
    The ideal graft does not exist with all grafts requiring degrees of compromise. Without doubt hamstring autograft has become the most popular ACL graft globally over the last 10years for a number of reasons. It is easier to harvest through small cosmetic scar and lends itself to “all inside” techniques. ACL reconstruction with bone patella bone(BTB) still has a significant role and is particularly favoured in elite athletes as well as for revision surgery. The bone blocks allow for more aggressive early rehabilitation suiting the elite athlete with a lower rerupture rate in this population reported.
    A recent study by Gabler et al in the American Journal of Sports Medicine has shown that the rupture rate for BTB in anatomic ACL to be comparative to hamstring. BTP knees had a greater incidence of anterior knee pain and crepitus, where there was a tendency towards increase laxity within the hamstring group. Clinical outcomes showed no differences. The long-term outcome of bone patella bone ACL reconstruction has been reported by Pinczewski. 90 BTP ACLs were reviewed at 20 years post-surgery. A 9% failure rate was reported on the index limb with a 30% rupture rate on the contralateral limb. Knee pain was present in 63%. Female patients although had a lower failure rate, they reported poorer IKDC scores had more activity-related pain and were less likely to participate in strenuous activities compared to males. Thus, bone patella bone may well have more significant donor site mobility long term than hamstring tendon in females.

    Indications

    INDICATIONS
    Primary or revison ACL reconstruction
    Graft choice for ACL reconstruction is largely based on surgeon experience and preference although several patient specific factors must be considered including patient size. The hamstring tendons may be too small to allow for an adequate graft particularly in petite females, similarly elite athletes would more likely be suited to a bone patella bone reconstruction particularly athletes that rely on hamstring power for speed. BTB also allows a more agressive rehabiltation program within the early months post surgery

    IMAGING
    The MRI should be reviewed to assess the length of the patella tendon. Patella Baja is a relative contraindication. Patella alta should be noted and considered when drilling the bone tunnels so as to ensure the bone block is within the tunnel.

    ALTERNATIVE OPERATIVE TREATMENT
    Alternative autograft choices include Hamstring tendons and Quadraceps tendon.
    Quadraceps tendon is gaining popularity in recent years. Harvesting has become easier with the advent of new minimally invaisive instrumentation resulting in a more cosmetic result. The tendon has the versitility of being used with or without a bone block and size of graft is relatively constant. Whilst biomechanically quadraceps would appear to be a suitable option, the long term data compared to hamstring and BTB is limited at present.


    Setup

    The patient is positioned in an Alvarado leg positioner with a side post.

    Operation

    The knee is prepared and draped using an arthroscopy drape. The knee is intially bent to 90o.

    The anatomical landmarks are marked and a skin incision is drawn out extending from 2cm above the inferior port of the patella to the centre of the tibial tubercle. The incision can be placed in the midline, or slightly medial in order to make tibial tunnel drilling easier

    The skin incision is then made and a full thickness skin flaps created using diathermy. Some surgeons try to preserve the infra patella brach of the saphenous nerve but i usually divide it.

    The edges of the tendon are identified and the central patella tendon paratenon excised sharply.

    The overall width of the patella tendon is measured and a decision is made regarding the most appropriate sized graft. For a 30mm tendon a 10mm graft is chosen, however for larger tendons the graft size can be extended by 1 or 2mm.

    A similar cutting block (marked patella) can be placed on the patella, but I prefer to do this free hand. A 20mm bone block is aimed for on the patella and is drawn on with a marker in line with the incised tendon. Again, forceps are used to measure the exact insertion point of the tendon on the patella so that a 20mm block can be created/measured. The same small surgical saw is used to incise the bone along the marked lines, being careful that the saw only penetrates approximately 10mm. Saw blades are availiable with measurements in order to aid this cut. The medial, lateral and superior aspects of the bone block are incised with the saw.

    The patella tendon is then lifted superiorly so that the inferior surface of the tendon insertion is visualised.

    The residual patella tendon is then approximated in a mid-portion with a 0 vicryl suture and bone wax can be placed within the bone site in order to reduce bleeding.

    The central third of the patella tendon is marked, in this case a 10mm graft is used.

    A 15 blade is used to create an incision at the proposed graft edges on either side. The blade should pass through the full thickness of the patella tendon at its mid-point between the tubercle and patella in order to avoid meniscal root injury.

    Dissecting scissors are then passed in to the incision and slid up and down the tendon to its bony insertions.

    The tibial tubercle bone block is created first.
    A patella tendon ACL resection block is used as a sizer. These are made by a number of companues but this one is made by Linvatec. It is placed in line with the incised tendon. Forceps are used to determine the exact insertion point of the tendon on the bone in order to measure an appropriate bone block. The cutting block has measurement lines on it in order to help create a 20, 25 or 30mm block. A 25mm tibial tubercle bone block is my prefernce in most cases.

    Two pins are placed in the cutting block to hold the jig in place while cutting the bone, the pins also to create holes in the bone block in order to pass sutures through at a later time point.

    A small sagittal saw is used to cut the medial, lateral and inferior aspect of the block along the jig in order to create a trapezoid shaped block. The saw should penetrate appromimately 10mm, using a saw blade with measurement on can assist with this.

    An osteotome is then used posterior to the tendon in order to cut the bone superiorly. The osteotome is then used to lever out the bone block and lift it away from the tibia. This can be done by placeing the osteotome either inferiorly or superiorly. As the proximal tibial cancellous bone a relatively soft, the block comes away easily. Any excess bone can be removed with a nibbler and placed back into the harvest site.

    The fat pad is then cleared away from the posterior aspect of the tendon.

    The posterior cut of the bone block can then be completed with the use of a sagittal saw or an osteotome. In this way the full thickness of the patella can be estimated in order to reduce the risk of patella fracture.

    Once the patella bone block has been removed it then can be drilled with a 1.6mm K-wire in order to pass traction sutures.

    The bone blocks on either end are then shaped with a small nibbler until they fit easily into a 10mm sizing tube. Potentially smaller bone blocks could be used but this does increase the risk of fracture.

    Sutures in the form of a number 2 high strength suture are placed in the bone block at either end, 2 sutures are placed in either bone block to allow the graft to be pulled into the ACL tunnel.

    Post Operative

    A standard post-operative ACL rehabilitation programme is followed. Potentially due to bony fixation more aggressive rehabilitation can be undertaken.
    Post-Operative
    Phase 1 (weeks 0-2)
    Assessment:
    Complete KOOS questionnaire and record data
    Milestones:
    Full passive knee extension
    90-110˚ active knee flexion
    Aims:
    Control pain, swelling and inflammation
    Restore active/passive ROM (emphasis on extension)
    Restore neuromuscular control
    Achieve 90-110˚ active knee flexion
    Achieve full passive knee extension +++
    Restore muscle strength
    Sample Intervention:
    Cryotherapy – used as often as possible in the first 5 days then as appropriate thereafter.
    Multidirectional mobilisations of PFJ as indicated
    SLR
    Heel Slides
    Mini Squats (0-30 deg)/ Ski Sits
    Weight bearing
    Hamstrings curls
    Prone knee hangs low load
    Prone knee lock outs
    Neuromuscular electrical stimulation if struggling with quads
    Phase 2 (2-5 weeks)
    Milestones:
    Minimum to moderate swelling.
    Patella mobility equal to opposite side
    Knee flexion greater than 110 degrees
    Mobilise independent of walking aids (pain free)
    SLR without extension lag
    Aims:
    Reciprocal stair climbing
    Active range of knee joint extension to 0° and flexion to at least 110°.
    Independent mobilisation.
    Avoidance of overloading the healing graft
    Satisfactory static proprioception – able to maintain a soft surface, single leg mini dip, knee unlocked for 15 seconds, with visual cues.
    Satisfactory static knee joint control – able to perform a unilateral step down to 45° knee flexion with neutral pelvic alignment.
    Good VMO control – able to activate EMG biofeedback machine during 3 sets of unilateral step downs to 45° knee flexion at a rate of 15 reps per minute with neutral pelvic alignment.
    Good gluteus maximus control – able to maintain 10° of hip extension with knee joint in 90° flexion for 10 seconds, with lumbar spine and pelvis in neutral x 10 reps.
    Good gluteus medius control – able to perform 10 reps of external hip rotation in side lying with heels together and with lumbar spine and pelvis in neutral.
    Satisfactory hamstrings control – able to perform 10 rep maximum on hamstring bench or using free weights, with neutral pelvic alignment. Able to perform a controlled forward knee flexion against black theraband at a rate of 15 reps per minute, with neutral pelvic alignment.
    Sample Exercises:
    Closed kinetic chain strengthening in pain free ranges (avoiding overloading graft typically 0-60 deg)
    Wall slides
    Step ups/step machine
    Patellar mobilisations.
    Open kinetic chain hamstring exercises.
    Quadriceps and hamstring muscle control exercises using theraband.
    VMO stabilisation exercises, eg bilateral dips/sit to stand/calf raises/ski sits.
    Use of biofeedback to re-educate both quadriceps and hamstring groups
    Exercise bike
    Swimming once satisfactory incision site. NO BREASTSTROKE.
    Progress stretches appropriately
    Note:
    If swelling persists review frequency/repetition of exercises.
    Patient must be achieving good VMO and glutes control.
    Phase 3 (5-6 weeks)
    Milestones:
    Full range of knee joint movement (knee flexion within 10˚ of non-operated leg)
    Quadriceps LSI >60%
    80-100% hamstrings muscle length
    Hamstrings LSI up to 70%
    Aims:
    Good knee joint control – able to perform 3 sets of unilateral step downs to 45° knee flexion, at a rate of 15 reps per minute.
    Good static proprioception – able to perform 3 sets of soft surface unilateral mini dips up to 45° knee flexion, at a rate of 15 reps per minute.
    80% quadriceps length.
    Commence jogging at 6 weeks, once they have achieved all the above aims/milestones
    Sample Exercises:
    Balance/neuromuscular exercises
    Single Leg Balance
    Wobble Board
    Single Leg Cone Pick Up
    Star Excursions
    Squats,
    Step downs
    Fitness work.
    Note:
    Intermediate knee class (IKC)
    Phase 4 (6-12 weeks)
    Milestones:
    Quadriceps LSI 60-80%
    Normal gait pattern
    Full knee ROM
    Minimal to no activity related effusion
    Aims:
    Minimal to no activity related effusion.
    No gait anomalies.
    Bilaterally equal static proprioception.
    Sample Exercises:
    Rhythmic sport activities at 12 weeks, shuttle runs, ball dribbling.
    Leg press.
    Note:
    The patient must continue strength training for hamstrings and closed kinetic chain strength training for quadriceps.
    Phase 5 (12-20 weeks)
    Milestones:
    Hamstrings LSI 85-100%
    Quadriceps LSI >80%
    Gastrocnemius and hip adductors LSI 100%
    Aims:
    Good dynamic proprioception – able to hop and land on a soft surface x 10 reps. Able to achieve 20 hops around the points of a 60cm square.
    Knee joint control – able to perform 20 reps of unilateral 90° knee joint sit to stand. Able to perform 10 reps of hop and land.
    Fitness – able to jog for 10 minutes at a rate of 8-9 km per hour.
    Sample Exercises:
    Open chain quadriceps.
    Jogging to include rotation and a graded impact element.
    Agility training – slalom running, lateral runs, squat thrusts, pro-fitter.
    Plyometrics may include skipping, hopping, star jumps.
    Strength training for all hip and knee joint muscle groups.
    Increase sport specific work.
    Note:
    Advanced knee class (AKC)
    Phase 6 (6-12 months)
    Milestones:
    Hamstring strength at least 75-90% of the quadriceps strength
    See discharge assessments for further objective assessment tools
    Aims:
    Return to sport/sport specific training.
    Note:
    The timing of the patient’s return to sport/training is dependent upon recovery and type of sport). Full contact sport may be delayed for up to 9-12 months post-operation. If in doubt then the patient should discuss with their consultant.

    Recommended Reading

    Samuelsen et al undertook a metanalysis of 47,613 patient following hamstring or patella tendon ACL reconstruction performed in 14 randomised controlled trials, 10 prospective comparative studies and 1 high quality national registry study. 7,560 of the patients had undergone a bone patella bone reconstruction vs 39,510 who underwent a hamstring reconstruction. The failure rate in the bone patella bone group was 2.8% vs 2.84% in the hamstring group. Pivot shift test was positive in 19% of the BTB group compared with 17% in the hamstring group. Lachman was positive in 25% in each group.

    The complications from harvesting bone patella bone that one mainly is concerned about is patella fracture and patella tendon rupture. Trying to avoid sawing too deep on the patella and creating sharp corners ( a rectangle, which can act as a stress riser) when harvesting the patella bone block can reduce this risk.
    In order to avoid patella tendon rupture, it is important to measure the overall width of the patella tendon and select and appropriate size for the individual. Harvesting too large a graft in a small patella tendon places the individual at an increased risk of rupture.

    Reference

    • orthoracle.com

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