PCL

Posterior cruciate ligament injuries are less common and occur with sport or dashboard injuries. A careful history and examination should make the diagnosis. It is important to identify isolated PCL injuries and combined ligament injuries. In isolated PCL injuries, surgery is reserved only for avulsion fractures and high grade symptomatic injuries. Non-operative treatment with adequate quadriceps physiotherapy is the recommended treatment for isolated grade 1 or 2 tears.Combined injuries are generally treated operatively. High-grade symptomatic PCL tears are treated by arthroscopic single or double tunnel or tibial inlay type of reconstruction.

Posterior cruciate ligament injuries are less common and form 3% of all knee injuries. In an acute trauma with haemarthrosis, PCL and combined injuries are more common and the incidence could be as high as 37%(Fanelli).

Mechanism of Injury

hyperflexion

In an athlete PCL injury occurs with hyperflexion and a posteriorly directed force to the proximal tibia. This can commonly occur during a tackle in football, rugby and wrestling. In motor vehicle accidents, a similar force can occur with dashboard injuries. High velocity injuries can produce PCL with combined ligament injuries when there is a posteriorly directed force along with rotation.

Diagnosis

PCL injury does not give the typical history of ‘pop’ or tearing sensation like ACL injuries. The mechanism of injury gives a clue to the diagnosis. Instability symptoms are less common with isolated PCL injuries.

Effusion can be minimal in isolated PCL injuries. There can be posterior knee pain. Should there be bruising posterolaterally, consider associated PLC injury.

The most sensitive tests to diagnose PCL injuries are to look for normal step off of the medial tibial plateau and the posterior drawer test. These tests are done with the knee at 90 degrees flexion. In normal knees the medial tibial plateau is approximately 1cm anterior to the corresponding medial femoral condyle.

Grade 1 Tibial plateau is still anterior but can be posteriorly translated (<5mm laxity)
Grade 2 Flush with medial femoral condyle (5-10mm laxity)
Grade 3 Tibial plateau is posterior to the condyle (>10mm laxity)

Posterior sag and quadriceps active tests are positive in grade 2 or 3 injuries and are easier to demonstrate in chronic PCL injuries. With the quadriceps active test, the examiner asks the patient to slide the foot down the couch. Quadriceps contraction causes the tibia to translate anteriorly from a subluxated position, confirming PCL insufficiency.

The reverse pivot shift is done with the tibia in external rotation and valgus. It may be positive even in normal patients.

A positive dial test at 90 degrees knee flexion is also indicative of PCL injury. If there is increased external rotation at both 30 and 90,then there is both PCL + PLC injury.

Investigations

Xrays of the knee help in assessing degree of posterior sag or for diagnosis of PCL avulsion fractures. MRI scans are not useful in chronic PCL tears as the PCL heals in an elongated position and may appear normal.

Patellofemoral wear or medial joint space narrowing may be seen in old PCL injuries as these compartments are overloaded in PCL deficiency.

Isolated PCL Injury

The natural history of isolated PCL tears is well known. Most studies have shown that patients with acute, isolated PCL tears treated nonoperatively achieve a level of knee function independent of the grade of laxity (Shelbourne, Parolie, Fowler). Tears of the lateral meniscus may be associated with PCL tears.

Shelbourne showed that 50% of patients get back to same or higher level of sporting activity. Subjective scores of patients with acute, isolated PCL injuries were independent of grade of PCL laxity and mean scores did not decrease with time from injury. No identifiable characteristics were identified that would help determine which patients with isolated PCL injuries would have deteriorating knee function.

Parolie and Bergfeld evaluated 25 athletes with isolated PCL tears at a mean of 6.2 years after injury. Eleven patients with acute injuries were treated with early range-ofmotion and quadriceps-strengthening exercises. Patients returned to sports in a PCL brace at an average of 6 weeks after injury. Seventeen patients (68%) were able to return to sports at the preinjury level; 4 (16%), at a decreased level of performance.

Non operative treatment (Posterior translation <10mm)

Grade 1 PCL injuries are treated with early range of motion, protected weight bearing for 2 weeks and quadriceps strengthening exercises.

For grade 2 injuries, immobilisation initially with a PCL brace in extension reduces tension on the anterolateral bundle and minimises posterior tibial subluxation by avoiding hamstring contraction. Open kinetic chain exercises are avoided to decrease increased patellofemoral load.

Return to sport can be as early as 6 weeks.

Indications for surgery

PCL injury with combined ligament injuries

Grade 3 PCL injury- A significant proportion of grade 3 injuries have associated PLC or PMC injuries.

PCL avulsion fracture with displacement

Surgical repair

PCL avulsions from the femur can be repaired. There are no indications for acute repair of midsubstance PCL tears.

PCL Reconstruction

Timing

In multiligamentous injuries the ideal timing for reconstruction is about 2 weeks. Capsular sealing occurs by this period. One may consider open technique in severe multiligamentous injuries due to fluid extravasation and to reduce operative time.

Graft Choice

Patellar tendon graft is satisfactory as long as the length of tendon is 40mm.

Hamstring graft has advantages of double bundle reconstruction but the killer turn of the graft and poorer fixation in the tibia can lead to residual laxity.

Quadriceps tendon graft has lower harvest morbidity or Achiles tendon allograft are now preferred as they also give option of double bundle reconstruction. The bone block is fixed to the tibia.

Achilles tendon allograft- Allografts decrease harvest morbidity and surgical time. The bone block is useful to achieve tibial fixation using inlay technique or transtibial technique. Double bundle reconstruction is possible by splitting the soft tissue portion of the graft.

Technique

Single or double bundle

In single bundle reconstruction, it is the stronger Anterolateral bundle that is reconstructed. In double bundle reconstruction, the posteromedial bundle is also reconstructed by drilling two femoral tunnels. This has potential biomechanical advantage and can reduce posterior laxity by about 3.5mm better than single bundle (Harner) The anterolateral bundle is tensioned at 90 degrees whereas the posteromedial bundle is tensioned at 30 degrees.

Transtibial or tibial inlay

The advantage of transtibial technique is to avoid open surgery for addressing the tibial attachment. There is however a ‘killer turn’ to the graft. By tibial inlay technique, the interval between medial head of Gastrocnemius and Semitendinosus is bluntly dissected and the bone block is resessed and fixed at the tibial footprint. The killer turn is avoided.

Transtibial technique

In the transtibial tunnel technique, the tibial PCL attachment is addressed arthroscopically. The procedure is performed with the patient supine with the leg held in a leg holder. After treating any meniscal or chondral lesions, the torn PCL is debrided to enhance visualization. Curved PCL instruments are used to elevate the posterior capsule away from the tibial ridge. Visualision of the PCL stump is achieved by using a posteromedial portal and use of a 70-degree scope. A needle is placed posteromedially under direct arthroscopic visualization just above the joint line to mark this portal. The tibial attachment extends well below the posterior joint line. After debridement of the PCL stump, a PCL guide is paced via the anteromedial portal and a guide pin is drilled from a point just distal and medial to the tibial tubercle and aimed at the distal and lateral aspect of the PCL footprint. This drill guide positioning creates a tibial tunnel that is relatively vertically oriented and creates an angle of ggraft orientation such that the graft will turn two very smooth 45° angles on the posterior aspect of the tibia eliminating the “killer turn” of 90° graft. A C-arm is helpful to confirm correct placement of the guide wire and also to make sure that the guide wire does not advance during reaming. A tunnel is then created with a reamer over the guide wire, with care taken to protect the posterior neurovascular structures. A curved PCL curette may be positioned to cup the tip of the guide wire and the arthroscope is in the posteromedial portal to visualise the tip of the guide wire.

The femoral tunnel is drilled using inside out or outside in technique avoiding trochlea articular cartilage. The tibial tunnel is rasped to avoid sharp turn. A Gore-Tex smoother may be used and a wire loop or suture passer helps in passing suture from femoral to tibial tunnel. A blunt trocar can be used to mobilise the graft up the back of the tibial tunnel into the knee. In single bundle reconstruction the graft is tensioned at 70 degrees knee flexion.

When multiple ligament surgeries are performed at the same operative session, PCL reconstruction is performed first, followed by ACL reconstruction and then collateral ligament surgery. The tourniquet may be released whilst doing the collateral ligament.

Postoperative rehabilitation

See rehabilitation page

Passive knee-flexion exercises are used to gain knee flexion slowly over 6 weeks. Open-kinetic-chain hamstring exercises (seated leg curls) are not used, since posterior tibial translation occurs with open-chain knee flexion exercises. Full return to sports is allowed when adequate quadriceps and hamstring strength is demonstrated (90% of that on the noninjured).

Outcomes

Fanelli and Edson presented the 2- to 10-year (24 to 120 month) results of 41 chronic arthroscopically assisted combined posterior cruciate ligament (PCL)-posterolateral reconstructions evaluated using Lysholm, Tegner, and Hospital for Special Surgery knee ligament rating scales, KT-1000 arthrometer testing, stress radiography, and physical examination. All patients had a single bundle Achilles tendon allograft reconstruction and PLC treated with Biceps tenodesis. Tibial stepoff was normal in 29 of 41 (70%) knees. KT 1000 difference was 1.81mm and Telos difference at 90 degrees with 32Lb load was 2.26mm. Postoperative Lysholm, Tegner, and Hospital for Special Surgery knee ligament rating scale mean values were 91.7, 4.92, and 88.7, respectively

Cooper and Stewart prospectively studied 44 patients having isolated or combined PCL reconstruction using the direct tibial inlay fixation technique. They were followed up for 2-10 years. There were 35 primary and 6 revision reconstructions. Surgery was performed in the acute or subacute setting (<8 weeks) in 34% (14/41) and chronic setting in 66% (27/41). Combined reconstructions involving the posterolateral corner, anterior cruciate ligament (ACL), or medial collateral ligament (MCL) were done in 85% (35/41). Final follow-up Telos stress radiography with 25 kg posterior load applied at 80 degrees to 90 degrees of flexion demonstrated average side-to-side difference of 4.11 mm (-2 to 10 mm).

No significant difference have been shown by other authors comparing Tibial inlay and transtibial technique (MacGillivray, Margheritini and Harner) Apsingi, Amis et al showed no significant laxity comparing single and double bundle reconstructions.

Ahn reviewed 36 PCL reconstructions (18 hamstring and 18 Allograft Achilles tendon). The hamstring group showed better Lysholm scores but there was no difference in Telos testing.

References

History and evaluation

Miyasaka KC, Daniel DM: The incidence of knee ligament injuries in the general population.Am J Knee Surg4:3-8,1991

Shelbourne KD, Davis TJ, Patel DV: The natural history of acute, isolated, nonoperatively treated posterior cruciate ligament injuries: A prospective study. Am J Sports Med 1999;27: 276-283

Fanelli GC: Posterior cruciate ligament injuries in trauma patients.Arthroscopy9:291-294,1993

Fanelli GC, Edson CJ: posterior cruciate ligament injuries in trauma patients: Part II.Arthroscopy11:526-529,1995

Fowler PJ, Messieh SS: Isolated posterior cruciate ligament injuries in athletes.Am J Sports Med15:553-557,1987

Covey CD, Sapega AA. Injuries of the posterior cruciate ligament. J Bone Joint Surg Am. 1993 Sep;75(9):1376-86

Shelbourne KD, Jennings RW, Vahey TN. Magnetic resonance imaging of posterior cruciate ligament injuries: assessment of healing. Am J Knee Surg. 1999 Fall;12(4):209-13.

Isolated PCL injury

Shelbourne KD, Muthukaruppan Y. Subjective results of nonoperatively treated, acute, isolated posterior cruciate ligament injuries. Arthroscopy. 2005 Apr;21(4):457-61.

Shelbourne KD, Davis TJ, Patel DV. The natural history of acute, isolated, nonoperatively treated posterior cruciate ligament injuries. A prospective study. Am J Sports Med. 1999 May-Jun;27(3):276-83.

Parolie JM, Bergfeld JA. Long-term results of nonoperative treatment of isolated posterior cruciate ligament injuries in the athlete. Am J Sports Med. 1986 Jan-Feb;14(1):35-8.

Fowler PJ, Messieh SS. Isolated posterior cruciate ligament injuries in athletes. Am J Sports Med. 1987 Nov-Dec;15(6):553-7.

Treatment

Miller MD, Cooper DE, Fanelli GC, Harner CD, LaPrade RF. Posterior cruciate ligament: current concepts. Instr Course Lect. 2002;51:347-51. Review

MacGillivray JD, Stein BE, Park M, Allen AA, Wickiewicz TL, Warren RF. Comparison of tibial inlay versus transtibial techniques for isolated posterior cruciate ligament reconstruction: minimum 2-year follow-up. Arthroscopy. 2006 Mar;22(3):320-8. Erratum in: Arthroscopy. 2006 Jun;22(6):A18.

Ahn JH, Yang HS, Jeong WK, Koh KH. Arthroscopic transtibial posterior cruciate ligament reconstruction with preservation of posterior cruciate ligament fibers: clinical results of minimum 2-year follow-up. Am J Sports Med. 2006 Feb;34(2):194-204.

Kim SJ, Park IS. Arthroscopic reconstruction of the posterior cruciate ligament using tibial-inlay and double-bundle technique. Arthroscopy. 2005 Oct;21(10):1271.

Ahn JH, Yoo JC, Wang JH. Posterior cruciate ligament reconstruction: double-loop hamstring tendon autograft versus Achilles tendon allograft–clinical results of a minimum 2-year follow-up. Arthroscopy. 2005 Aug;21(8):965-9.

Fanelli GC, Orcutt DR, Edson CJ.The multiple-ligament injured knee: evaluation, treatment, and results. Arthroscopy. 2005 Apr;21(4):471-86.

Burks RT, Schaffer JJ. A simplified approach to the tibial attachment of the posterior cruciate ligament. Clin Orthop Relat Res. 1990 May;(254):216-9.

Zehms CT, Whiddon DR, Miller MD et al. Comparison of a double bundle arthroscopic inlay and open inlay posterior cruciate ligament reconstruction using clinically relevant tools: a cadaveric study. Arthroscopy. 2008 Apr;24(4):472-80.

Apsingi S, Nguyen T, Bull AM, Unwin A, Deehan DJ, Amis AA. Control of laxity in knees with combined posterior cruciate ligament and posterolateral corner deficiency: comparison of single-bundle versus double-bundle posterior cruciate ligament reconstruction combined with modified Larson posterolateral corner reconstruction. Am J Sports Med. 2008 Mar;36(3):487-94.

Margheritini F, Mauro CS, Rihn JA, Stabile KJ, Woo SL, Harner CD. Biomechanical comparison of tibial inlay versus transtibial techniques for posterior cruciate ligament reconstruction: analysis of knee kinematics and graft in situ forces. Am J Sports Med. 2004 Apr-May;32(3):587-93

Grade 1 to 2 injuries (<10mm opening on varus stress with <10 degrees difference in external rotation on dial test)

The recommended treatment for patients with Grade 1 to 2 posterolateral knee complex injuries (partial injuries) initially is nonoperative. The knees are treated in a ROM brace that is kept locked for the first 3 weeks at 15 degrees. Static quadriceps exercises and Straight leg raises are commenced early. Patients are nonweightbearing for this initial period. At 3 weeks, patients are allowed to work on range of motion (ROM) to 90 degrees and commence weightbearing. It is important to start Closed chained quadriceps exercises, with the avoidance of active hamstring exercises for the first 6 to 10 weeks after injury.

Patients who complain of pain or instability at 3 months post injury need to be reevaluated carefully to determine whether they have any instability present in their knee or whether they have any varus thrust in gait. MRI scans are unhelpful in such situations. If the pain is accentuated by the examiner placing the knee in a figure-four position (the figure-of-four test), these patients may have a tear of their popliteomeniscal fascicles. Tearing of these fascicles results in increased lateral meniscal hypermobility and the meniscus is entrapped in the joint when the knee is put in the figure-four position. Patients may benefit from repair of the lateral meniscus back to the popliteomeniscal fascicles of the popliteal hiatus.

Grade 3 injuries (>10mm joint opening and/or >10 degrees external rotation on dial test)

Acute repair is generally better and nonoperative treatment is not recommended for grade 3 injuries. The timing of repair is critical and is ideally performed within 2 weeks. Delays beyond this period can make identification of posterolateral structures and soft tissue planes difficult.

In the presence of combined ligament injuries, PLC is repaired and ACL/PCL treated by simultaneous or delayed reconstruction. It is important to avoid arthrofibrosis.

Technique of Repair

1. Check common peroneal nerve prior to surgery
2. MRI scans useful to assess structures involved. Check biceps femoris as it is an important landmark for dissection.
3. Dry arthroscopy useful as mentioned above
4. Lateral curvilinear incision
5. Identify Common Peroneal nerve through surgical window posterior to IT Band
6. Fibular neck avulsion fracture fixed with anchors, screw with washer or tension band wiring.
7. Inferior lateral geniculate artery may be encountered
8. Femoral attachment of LCL and Popliteus identified through anterior window to Iliotibial Band and reattached anatomically using anchors, suture or recess technique.
9. LCL attachtment on the femur is proximal and posterior to lateral epicondyle. The popliteus attachment is about 18mm anterior and distal to this point.
10. Popliteo-fibular ligament is present in most patients and identified close to musculo-tendinous junction and repaired.
11. Direct repair of midlateral capsule, IT band tear, meniscus tear or Biceps Femoris tear may be needed.
12. Occasionally, augmentation with Hamstring graft or a slip of IT band or Biceps femoris may be necessary.
13. Tensioning is done at 30 degress knee flexion and slight internal rotation and valgus.

Chronic Injury

Chronic injury to the posterolateral corner is a more difficult problem. The important aspects of injury assessment are alignment, gait and assessing coexisting ACL/PCL injury. Long leg alignment radiographs are essential and MRI scans are less helpful. Combined reconstruction has the best option of successful results.

If there is varus alignment, then a medial opening wedge tibial osteotomy is recommended. This contols varus laxity and external rotation even without repair/reconstruction of posterolateral structures (Arthur, LaPrade).

Reconstruction of the posterolateral corner has evolved from proximal advancement of posterolateral structures (Noyes, Hughston), nonanatomical reconstruction purely addressing LCL (Hughston, Clancy) to more anatomical reconstruction addressing popliteus and LCL (Larsen, LaPrade, Veltri and Warren, Noyes, Sekiya, Yoon). The anatomical reconstructions can be fibula based or Tibia and Fibula based with one or two femoral tunnels.

Techniques of Reconstruction

Images

Postoperative Rehabilitation

1. Aim to regain range of motion
2. Knee brace for 12 weeks
3. Avoid active Hamstring exercises and external rotation of tibia for 3 months.
4. Initial period of nonweightbearing followed by closed chain quadriceps physiotherapy and gentle leg presses from 6 weeks to 3 months.
5. Exercise bike at 6 weeks with mini squats and proprioceptive exercises
6. Treadmill and straight line activities at 4 months
7. Sports after 10-12 months.

Outcomes of PLC Reconstruction

This link gives the evidence behind anatomical posterolateral corner reconstruction.

There are no prospective randomised studies comparing reconstruction techniques. Nau compared two different reconstruction techniques and found no significant difference in varus laxity. There can be a tendency to increased internal rotation.

Noyes(2007)- 14 knees, 2-13.7 years follow up- 13/14 knees had near normal varus laxity

Yoon (2006) compared anatomical reconstruction in 21 knees with a sling procedure in 25 knees. There was >5mm varus laxity in 14% of anatomical reconstructed knees.

Acute repair of PLC provides good results (Hughston, Krukhaug, Veltri) and is recommended over chronic reconstruction. Stannard compared repair and reconstruction and suggests that results from Acute repair is inferior to anatomical reconstruction.

Management of Common Peroneal nerve injuries with PLC injuries

Common Peroneal injuries are present in upto 41% of PLC with bicruciate injuries (Niall and Keating). Keating showed that complete recovery occurred in 21% and no useful recovery of motor or sensory function in 50%. There is also risk of nerve damage with surgical repair/reconstruction.

The management of the nerve injury and the rehabilitation of the ligament injury also becomes more complex.

Garozzo recommends surgical management of the nerve injury and that a transfer procedure to nerve repair enhances neural regeneration, dramatically improving the surgical outcome of these injuries.

References

Basic Science

Raheem O, Philpott J, Ryan W, O’Brien M. Anatomical variations in the anatomy of the posterolateral corner of the knee. Knee Surg Sports Traumatol Arthrosc. 2007 Jul;15(7):895-900. Epub 2007 Feb 15

Alpert JM, McCarty LP, Bach BR Jr. The posterolateral corner of the knee: anatomic dissection and surgical approach.J Knee Surg. 2008 Jan;21(1):50-4.

Veltri DM, Deng XH, Torzilli PA, Maynard MJ, Warren, RF. The role of the popliteofibular ligament in stability of the human knee. A biomechanical study. Am J Sports Med. 1996;24:19-27.

LaPrade RF, Resig S, Wentorf F, Lewis JL. The effects of grade III posterolateral knee complex injuries on anterior cruciate ligament graft force. A biomechanical analysis. Am J Sports Med. 1999;27:469-75.

Seebacher JR, Inglis AE et al. ‘The structure of the posterolateral aspect of the knee’. J Bone Joint Surg Am. 1982;64:536-541.

Assessment

Hughston JC, Norwood LA Jr. The posterolateral drawer test and external rotational recurvatum test for posterolateral instability of the knee. Clin Orthop. 1980;147:82-7.

Covey DC. Current Concepts review. Injuries to the posterolateral corner of the knee. J Bone Joint Surg Am. 2001.83:106

LaPrade RF. Arthroscopic evaluation of the lateral compartment of knees with grade 3 posterolateral knee complex injuries. Am J Sports Med. 1997;25:596-602.

Bae JH, Choi IC, Suh SW, Lim HC, Bae TS, Nha KW, Wang JH.Evaluation of the reliability of the dial test for posterolateral rotatory instability: a cadaveric study using an isotonic rotation machine. Arthroscopy. 2008 May;24(5):593-8. Epub 2008 Jan 25

Management

Noyes FR, Barber-Westin SD: Posterolateral knee reconstruction with an anatomical bone-patellar tendonbone reconstruction of the fibular collateral ligament. Am J Sports Med 2007;35:259-273.

Ricchetti ET, Sennett BJ, Huffman GR.Acute and chronic management of posterolateral corner injuries of the knee. Orthopedics. 2008 May;31(5):479-88; quiz 489-90

Krukhaug Y, Molster A, Rodt A, Strand T: Lateral ligament injuries of the knee. Knee Surg Sports Traumatol Arthrosc 1998;6:21-25.

Veltri DM, Warren RF. Isolated and combined posterior cruciate ligament injuries. J Am Acad Orthop Surg. 1993;1:67-75.

VeltriDM, WarrenRF: Operative treatment of posterolateral instability of the knee. Clin Sports Med 1994; 13:615-627

Albright JP, Brown AW. Management of chronic posterolateral rotatory instability of the knee: surgical technique for the posterolateral corner sling procedure. Instr Course Lect. 1998;47:369-78

Clancy WG Jr, Shepard MF, Cain EL Jr. Posterior lateral corner reconstruction. Am J Orthop. 2003;32:171-176

Fanelli GC, Feldmann DD. ‘Management of combined ACL/PCL/posterolateral complex injuries of the knee’. Oper Tech Sports Med. 1999;7:143-149.

StannardJP, BrownSL, FarrisRC, McGwinGJr, VolgasDA: The posterolateral corner of the knee: Repair versus reconstruction. Am J Sports Med 2005; 33:881-888.

FanelliGC, LarsonRV: Practical management of posterolateral instability of the knee. Arthroscopy 2002; 18(2 suppl 1):1-8

LarsonRV: Isometry of the lateral collateral and popliteofibular ligaments and techniques for reconstruction using a free semitendinosus tendon graft. Oper Tech Sports Med 2001; 9:84-90

Nau T, Chevalier Y, Hagemeister N, Deguise JA, Duval N. Comparison of 2 surgical techniques of posterolateral corner reconstruction of the knee. Am J Sports Med. 2005 Dec;33(12):1838-45

Laprade RF, Engebretsen L, Johansen S, Wentorf FA, Kurtenbach C. The effect of a proximal tibial medial opening wedge osteotomy on posterolateral knee instability: a biomechanical study. Am J Sports Med. 2008 May;36(5):956-60.

Arthur A, LaPrade RF, Agel J.Proximal tibial opening wedge osteotomy as the initial treatment for chronic posterolateral corner deficiency in the varus knee: a prospective clinical study. Am J Sports Med. 2007 Nov;35(11):1844-50.

Niall DM, Nutton RW, Keating JF. Palsy of the common peroneal nerve after traumatic dislocation of the knee. J Bone Joint Surg Br. 2005 May;87(5):664-7.

Garozzo D, Ferraresi S, Buffatti P. Surgical treatment of common peroneal nerve injuries: indications and results. A series of 62 cases. J Neurosurg Sci. 2004 Sep;48(3):105-12