In lower extremities affected with poliomyelitis, genu recurvatum is typical and is associated with severe valgus alignment, ligamentous laxity, or both. 1,3,4 In the presence of such neuromuscular disease, quadriceps strength may be diminished to the extent where patients rely on locking the knee in full extension or even hyperextension to ambulate. 1 Furthermore, a plantarflexion contracture of the ankle may be present thereby predisposing the knee to hyperextension especially at heel strike. Because of the bony deformity, muscle weakness, and paralysis associated with neuromuscular disorders such as poliomyelitis, genu recurvatum likely is to recur after surface replacement arthoplasty in these patients. 1,5 Therefore, TKA has been considered relatively contraindicated in this clinical setting. 1,5,6 The presence of genu recurvatum may raise concern about its recurrence or instability after TKA. 6 Therefore, when considering TKA in patients presenting with knee hyperextension, specific attention should be given to determining the relative strength of the quadriceps, hamstrings, and gastrocnemius complex. The presence of an ankle plantar flexion contracture and ankle dorsiflexion strength also should be determined.
Several techniques have been suggested to correct genu recurvatum at the time of TKA. These include posterior capsular plication, 2 proximal and posterior transfer of the collateral ligaments, 3 underresection of the bone ends with the use of thicker components, 4 and tightening the extension gap to prevent recurvatum. 3 All of these techniques rely of the integrity of the retained collateral ligaments to prevent hyperextension.
Insall 4 warned, however, that paralytic types of recurvatum tend to recur and suggested using a more constrained prosthesis. Giori and Lewallen 1 also recommended alternative techniques including the use of a hinged knee replacement or even arthodesis, especially when quadriceps weakness is severe. They also warned that operative correction of the deformity at the time of TKA might reduce walking function by limiting a patient’s ability to lock the knee in full extension. 1
Fortunately, in most cases not involving neuromuscular disease, the use of these techniques is not required to correct knee hyperextension. 6 In a retrospective study done at our institution, 57 TKAs were done in 53 patients with at least a 5° hyperextension deformity. 6 The average recurvatum measured 11° (range, 5°–20°). Patients with neuromuscular diseases were excluded. A posterior cruciate-retaining prosthesis was used in all cases. Introperatively, the hyperextension deformity was corrected in all but one knee (98%). Fifty-four knees had full extension intraoperatively after prosthetic implantation (95%). Two knees (3%) had a 10° contracture at the end of the operation. Interestingly, no significant relationship was seen between the degree of recurvatum before surgery and the number or extent of intraoperative medial, lateral, posterior, or lateral retinacular ligamentous releases. Furthermore, the tibiofemoral joint line was raised an average of only 0.6 mm with no measurable change seen in 38 knees (66%). In four knees (7%), the joint line was lowered 2 to 3 mm and in 15 knees (26%) the joint line was raised between 2 and 5 mm. Therefore, the operative correction of the hyperextension deformity was achieved without the use of relatively thicker components or collateral ligament transfer.
At the most recent followup (average, 4.5 years), only two knees (3.5%) had a hyperextension deformity (10° each). Extension in the entire study group averaged 0°. Importantly, final extension was statistically greater in knees with residual medial instability at the end of the operation. The two knees with hyperextension at final followup had residual medial instability of between 5 and 10° after implantation of the prothesis. 6
Insall and Haas 5 also observed that a knee that does not hyperextend at the conclusion of surgery would not develop recurvatum later except in patients who lack muscle control. Similarly, Schurman et al, 7 in evaluating 71 total condylar knee replacements in patients without major neuromuscular diseases, reported that significant increases in extension did not occur after hospital discharge.
Krackow and Weiss 3 observed excess collateral ligamentous laxity in three of four patients with recurvatum after knee arthoplasty. Operative repositioning of either the medial or lateral collateral ligament was used to correct the hyperextension deformity.
Finally, in a study reviewing the results of TKA in 16 knees affected with poliomyelitis, Giori and Lewallen 1 reported that recurrence of instability and progressive functional deterioration is possible in all knees affected with such a neuromuscular condition. The authors also reported a correlation between diminished quadriceps strength and the recurrence of hyperextension along with less pain relief in these patients.
In the absence of neuromuscular disease, genu recurvatum tends not to recur after TKA. Great care should be taken to avoid even small degrees of collateral ligamentous instability at implantation, because this type of instability has been associated with increased extension, including hyperextension in the postoperative period. Although the etiology of the hyperextension deformity should be evaluated thoroughly before to surgery, the presence of genu recurvatum does no preclude a well-functioning TKA. Genu recurvatum, alone, is not a contraindication to TKA.
1. Giori NJ, Lewallen DG: Total knee arthroplasty in limbs affected by poliomyelitis. J Bone Joint Surg 84A:1157–1161, 2002.
2. Krackow KA: The Technique of Total Knee Arthroplasty. St Louis, CV Mosby 1990.
3. Krackow KA, Weiss PC: Recurvatum deformity complicating performance of total knee arthroplasty: A brief note. J Bone Joint Surg 72A:268–271, 1990.
4. Insall JN: Surgical Techniques and Instrumentation in Total Knee Arthroplasty. In Insall JN, Windsor RE, Scott WN, Kelly MA, Aglietti P (eds). Surgery of the Knee. New York, Churchill Livingstone 739–804, 1993.
5. Insall JN, Haas SB: Complications of Total Knee Arthroplasty. In Insall JN, Windsor RE, Scott WN, Kelly MA, Aglietti P (eds). Surgery of the Knee. New York, Churchill Livingstone 891–934, 1993.
6. Meding JB, Keating EM, Ritter MA, Faris PM, Berend ME: Total knee replacement in patients with genu recurvatum. Clin Orthop 393: 244–249, 2001.
7. Schurman DJ, Parker JN, Ornstein D: Total condylar knee replacement: A study of factors influencing range of motion as late as two years after arthroplasty: J Bone Joint Surg 67A: 1006– 1014, 1985.
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8. Tew M, Forster IW: Effect of knee replacement on flexion deformity. J Bone Joint Surg 69B3: 395–399, 1987.