DEFINITION

Complete tears of the patella tendon are best classified into acute versus chronic.

Partial tears often can be managed nonoperatively. The functional integrity of the extensor mechanism is the key to determining the need for surgical repair.

This chapter focuses on the surgical treatment of complete tendon disruption.

 

 

ANATOMY

 

The patella tendon is approximately 30 mm wide × 50 mm long, with a thickness of 5 to 7 mm.1

 

The origin on the inferior pole of the patella is juxtaposed to the articular cartilage on the deep side and becomes confluent with the periosteum of the patella anteriorly.2

 

The tibial insertion is narrower and invests the entirety of the tibial tubercle.

 

The overlying peritenon is thought to be the cellular source for healing of tendon injuries.

 

PATHOGENESIS

 

 

Tendon rupture usually is the result of underlying tendinosis.6 There is some evidence of genetic predisposition to tendon rupture.

 

Certain conditions predispose individuals to tendon rupture, including renal dialysis, chronic corticosteroid use, fluoroquinolone antibiotics, and corticosteroid use.

 

NATURAL HISTORY

 

The natural history of an untreated patella tendon is complete extensor mechanism dysfunction.

 

Untreated acute ruptures result in chronic lesions that are more difficult to manage surgically. These often require reconstructive procedures and have inferior functional results.

 

PATIENT HISTORY AND PHYSICAL FINDINGS

 

Patients with acute tendon tears may report an audible “pop” or the sensation of their knee giving way.

 

Patients with chronic injuries may report ambulatory difficulty and pain. These injuries often are treated with bracing before definitive evaluation.

 

The loss of active knee extension is the key physical examination finding when evaluating for patella tendon rupture.

 

Loss of tension in the patella tendon with the knee at 90 degrees of flexion and patella alta are indirect signs of rupture.

IMAGING AND OTHER DIAGNOSTIC STUDIES

 

Plain radiographs may reveal patella alta, avulsion fractures, Osgood-Schlatter lesions, or other concomitant knee injuries.

 

Magnetic resonance imaging scans may be helpful in determining the exact location of the rupture and evaluating concomitant intra-articular knee lesions.

 

DIFFERENTIAL DIAGNOSIS

 

 

Quadriceps tendon rupture Patella fracture

 

Tibial tubercle avulsion fracture

 

NONOPERATIVE MANAGEMENT

 

Nonoperative management should be considered only for patients who are not surgical candidates because of medical comorbidities.

 

SURGICAL MANAGEMENT

 

Although not considered to be a surgical emergency, prompt surgical management of acute patella tendon ruptures is recommended to avoid the difficulties of repairing a chronic rupture.

 

Preoperative Planning

 

 

Repairs of chronic injuries often require allograft tissue availability and careful surgical planning. Significant patella alta may require proximal release in conjunction with the repair.

Positioning

 

Supine positioning is recommended.

 

Use of a tourniquet may preclude proper repair tensioning in chronic injuries. If one is used, it should only be elevated after flexing the knee.

 

Prepping and draping of both lower extremities allows use of contralateral limb as a template for patella positioning.

 

Approach

 

 

An anterior approach is used, regardless of the repair technique. A midline longitudinal incision is made over the patella tendon.

 

The peritenon is incised longitudinally and sharply dissected away from the underlying tendon.

 

 

P.531

 

TECHNIQUES

• Acute Repair

Midsubstance

Grossly pathologic tendon tissue is aggressively débrided. The full length of the patella tendon is exposed.

 

 

Two Krackow locking stitches are placed in each tendon stump with no. 2 or no. 5 FiberWire (Arthrex, Inc., Naples, FL; TECH FIG 1A).

 

 

 

Any required retinacular repair stitches are placed with absorbable suture before the tendon repair. The four proximal core sutures are tied to the four distal core sutures with the knee in full extension. Integrity of the repair is evaluated by checking the maximal flexion possible prior to gap formation.

 

The peritenon is closed with absorbable suture.

Proximal Avulsion

 

Grossly pathologic tendon or bone is removed and exposure of the inferior pole of the patella is performed (TECH FIG 1B,C).

 

There are two main repair techniques for proximal avulsions: transosseous drill holes or suture anchors.

 

Transosseous drill hole technique

 

Two Krackow locking sutures are placed in the tendon stump from proximal to distal and then proximal again with no. 2 or no. 5 FiberWire. The two most central sutures are marked with a marking pen (TECH FIG 1D).

 

Three equally spaced transosseous drill hole are made with a 2.0 drill bit from distal to proximal with exposure of the exit holes out the superior pole of the patella (TECH FIG 1E).

 

The Hewson suture passer or a similar device (Smith & Nephew, Andover, MA) is then passed from proximal to distal as the 2.0 drill bit is removed from the bone. One suture is passed through the lateral hole and medial hole respectively, and the two central marked sutures are passed through the center hole. The central sutures are then passed underneath the quadriceps tendon one laterally and one medially and tied.

 

 

 

TECH FIG 1 • A. Repair of acute midsubstance tear. B,C. Exposure of patella and removal of pathologic tissue off inferior patella. (continued)

 

 

Suture anchor technique

 

Three suture anchors are placed in the inferior pole of the patella, equally spaced along the anatomic tendon footprint.

 

 

We prefer the 5.0 Bio-Corkscrew FT Suture Anchor (Arthrex) loaded with no. 2 FiberWire. The suture is pulled through the anchor eyelet to produce long and short suture arms.

 

The long suture arm is passed down and back up the tendon stump in a locking Krackow fashion (TECH FIG 1F).

 

The tendon is manually reduced to the inferior pole of the patella, and the slack is taken out by the short arm of suture pulled through the eyelet.

 

Each suture pair is tied securely to complete the repair.

 

 

Repair integrity is evaluated by checking the maximal flexion possible before gap formation. The peritenon is closed with absorbable suture.

Distal Avulsion

 

Grossly pathologic tendon or bone is removed.

 

The tibial tubercle is exposed.

 

Two suture anchors are placed in the tibial tubercle.

 

We prefer the 5.0 Bio-Corkscrew FT Suture Anchor loaded with no. 2 FiberWire.

 

The suture is pulled through the anchor eyelet to produce long and short suture arms. The long suture arm is passed up and

 

P.532

back down the tendon stump in a locking Krackow fashion (TECH FIG 1G).

 

 

 

TECH FIG 1 • (continued) D. Krackow sutures placed in medial and lateral portion. E. Three equally spaced transosseous drill holes are made from distal to proximal. F. Repair of acute proximal avulsion with suture anchor technique. G,H. Repair of acute distal avulsion.

 

 

The tendon is manually reduced to the tibial tubercle, and the slack is taken out by the short arm of suture pulled through the eyelet.

 

Each suture pair is tied securely to complete the repair.

 

 

Repair integrity is evaluated by checking maximal flexion possible before gap formation. The peritenon is closed with absorbable suture.

• Reconstruction of Chronic Tears

   

  Reconstruction of a chronic tear begins with aggressive débridement of dysplastic tissue.

   

  In order to pull the patella down distally for repair of patella tendon, the quadriceps may need to be mobilized from its scarred down position on the distal femur.

   

   

  Remaining tendon tissue is assessed for possible repair. The tibial tubercle is exposed.

   

  The Achilles allograft is prepared with 15- × 25-mm bone block.

   

  A rectangular box is cut out of the tubercle with an oscillating microsurgical saw and osteotomes to receive the bone block.

   

  The block is secured to the tubercle with 2- × 3.5-mm cortical screws (TECH FIG 2A).

   

  Suture anchors are placed into the distal pole of the patella and onto the anterior cortex of the patella to secure allograft tendon to the patella (TECH FIG 2B).

   

  The allograft tendon is draped over the quadriceps tendon and muscle fascia and secured with nonabsorbable suture.

   

  P.533

   

   

   

  TECH FIG 2 • Chronic reconstruction with Achilles tendon allograft. The bone block is inlayed into the tibial tubercle and fixed with screws or staples. The soft tissue end of the graft is sutured into the patella with suture anchors and into the quadriceps with heavy nonabsorbable sutures. A. Lateral view. B. Anteroposterior view.

• Augmentation Procedures

 

After the repair has been completed, it is assessed for any need for augmentation.

 

The following materials can be used for augmentation. They are placed in a box-stitch fashion through drill holes in the patella and tubercle (TECH FIG 3A):

 

 

Mersilene tape No. 5 FiberWire

 

TECH FIG 3 • Augmentation of the repair can be with a box-stitched suture (A) or a soft tissue graft (B). No. 5 Ethibond

Steel wire Cerclage cables

Tibialis tendon allograft

A semitendinosus autograft also may be harvested proximally (while leaving its distal insertion intact) and passed through a drill hole in the patella and either through a drill hole in the tubercle or potted into the proximal tibia if the length is insufficient (TECH FIG 3B).

 

 

P.534

 

PEARLS AND PITFALLS

 

Preoperative

planning

• Failure to recognize significant patella alta may lead to abnormal knee kinematics

  and weakness of extension.

• In a chronic reconstruction, the quadriceps may need to be mobilized off the distal femur.

Surgical

technique

• Reattachment of the patella tendon into its anatomic footprint on the patella is

essential for reestablishing normal patellofemoral kinematics to avoid tilt of patella.

Intraoperative ▪ Maximum allowed knee flexion angle without repair gap formation is determined

assessment immediately after repair.

 

 

POSTOPERATIVE CARE

 

Weight bearing is allowed with the knee braced in extension.

 

Early flexion allowances are determined intraoperatively by the quality of the tendon tissue and repair.

 

Active-assisted range of motion is advanced as tolerated with the goal of 90 degrees of flexion by 4 to 6 weeks and full motion by 10 to 12 weeks after repair.

 

Strengthening is initiated immediately with isometric quadriceps contractions and progressed to straight-leg raises at 6 weeks.

 

Return to unrestricted activities is delayed until 6 months.

 

 

OUTCOMES

Marder and Timmerman9 reported excellent results in 12 of 14 patients treated with acute repair without augmentation.

Larson and Simonian7 reported excellent results (mean Lysholm score, 97.5) in four cases of acute repair augmented with autologous semitendinosus graft placed in a looped fashion.

Lindy et al8 reported excellent results in 24 patients repaired acutely and augmented with Mersilene tape placed in a looped configuration.

Fujikawa et al5 reported good results with a patella tendon repair augmented with a synthetic figure-8 weave performed on six patella tendon ruptures. They noted that the augmentation device is allowed for early mobilization and good functional outcome.

Two recent biomechanical studies show that an augmented repair is stronger than an unaugmented repair11 and that suture anchor repair is at least as strong as repair through drill holes.3

In an unpublished retrospective study of 14 patients with chronic patella tendon ruptures 2 years status post allograft reconstruction with Achilles allograft or whole bone patellar tendon bone allograft, all patients were found to have the ability to perform a straight-leg raise with an average extensor lag of only 8 degrees. No ruptures were reported.

Two cases of successful treatment of chronic patella tendon ruptures with Achilles allograft reconstruction have been reported.4,10

 

 

COMPLICATIONS

Rerupture is the most worrisome complication. Infection is uncommon but devastating.

Residual quadriceps weakness and extensor lag are more common with repairs of chronic injuries.

 

 

REFERENCES

1. Andrikoula S, Tokis A, Vasiliadis HS, et al. The extensor mechanism of the knee joint: an anatomical study. Knee Surg Sports Traumatol Arthrosc 2006;14:214-220.

    

    

2. Basso O, Johnson DP, Amis AA. The anatomy of the patellar tendon. Knee Surg Sports Traumatol Arthrosc 2001;9:2-5.

    

    

3. Bushnell BD, Byram IR, Weinhold PS, et al. The use of suture anchors in repair of the ruptured patellar tendon. Am J Sports Med 2006;34:1492-1499.

    

    

4. Falconiero RP, Pallis MP. Chronic rupture of a patellar tendon: a technique for reconstruction with Achilles allograft. Arthroscopy 1996;12: 623-626.

    

    

5. Fujikawa K, Ohtani T, Matsumoto H, et al. Reconstruction of the extensor apparatus of the knee with the Leeds-Keio ligament. J Bone Joint Surg Br 1994;76B:200-203.

    

    

6. Kannus P, Jozsa L. Histopathological changes preceding spontaneous rupture of a tendon. A controlled study of 891 patients. J Bone Joint Surg Am 1991;73A:1507-1525.

    

    

7. Larson RV, Simonian PT. Semitendinosus augmentation of acute patellar tendon repair with immediate mobilization. Am J Sports Med 1995;23:82-86.

    

    

8. Lindy PB, Boynton MD, Fadale PD. Repair of patellar tendon disruptions without hardware. J Orthop Trauma 1995;9:238-243.

    

    

9. Marder RA, Timmerman LA. Primary repair of patellar tendon rupture without augmentation. Am J Sports Med 1999;27: 304-307.

    

    

10. McNally PD, Marcelli EA. Achilles allograft reconstruction of a chronic patellar tendon rupture. Arthroscopy 1998;14:340-344.

     

     

11. Ravalin RV, Mazzocca AD, Grady-Benson JC, et al. Biomechanical comparison of patellar tendon repairs in a cadaver model. Am J Sports Med 2002;30:469-473.