Partial rupture of the Results after

operative

INGRID WIGERSTAD

From the

patellar ligament

treatment JON KARLSSON,*† MD, PhD, OLOF LUNDIN,* MD, LOSSING,‡ RPT, AND LARS PETERSON,* MD, PhD

*Department of Orthopaedic Surgery, East Hospital, and ‡Rehabilitation Medicine, Sahlgren Hospital, University of Göteborg, Göteborg, Sweden incidence

ABSTRACT Partial rupture of the patellar ligament, also known as jumper’s knee, is defined as a repetitive overload lesion at the bone-ligament junction at the lower patellar pole. It is found mainly in athletes and is caused either by microruptures or partial macroruptures of the proximal part of the ligament. The abnormal anatomical lesion is focal degeneration, microruptures and macroruptures, and devitalized tissue at the insertion of the patellar ligament. Proliferation and neovascularization are often found, as well as degeneration and incomplete tissue healing. Surgical treatment is indicated only if a prolonged and well-supervised conservative treatment program fails. We operated on 78 patients with jumper’s knee, by carefully removing the abnormal tissue from the ligament. At follow-up examination, 71 of 78 patients had excellent or good functional results and complete resumption of sports activities. Objective measurements of thigh muscle strength using a Cybex II dynamometer correlated with the functional results at a low angular velocity.

in

more

intensive

program fails should surgery be considered.

MATERIALS AND METHODS

During the period from 1971 to 1988, 86 patients were operated on for partial rupture of the patellar ligament at the Department of Orthopaedic Surgery at the University of Goteborg. Three patients had moved abroad and five could not be traced, leaving a follow-up study group of 78 patients (72 men and 6 women) with a range of follow up from 2 to 15 years (mean, 5 years). There is no evident explanation for the low number of women in this retrospective study, other than the fact that there was a high number of male soccer players among our patients. All patients, except three, were active in sports prior to injury (Table 1). The mean age at operation was 25 years (range, 15 to 51 years). All patients had Stage 3 jumper’s knee (Table 2). 2, 11 The onset of symptoms in these 78 patients was acute in 40

&dquo;jumper’s knee&dquo; has been used to describe several peripatellar diseases, both in the patellar ligament and, less frequently, in the quadriceps tendon, at the inferior or the superior pole of the patella, respectively. It is especially The term

cases

found in athletes involved either in repetitive activity (microruptures) with repetitive peak strain, such as running, or explosive activity (macroruptures), such as jumping and kicking. Only a few reports are found in the literature dealing with the etiology and treatment of partial rupture of the patellar ligaments~,6, 10, 13, 14 During the past few years, the

and chronic in 38.

Preoperatively, all had

through a supervised treatmonths, including a prolonged period of rest, without success. The preoperative training program consisted primarily of isometric quadriceps and hamstrings contractions at different knee angles, followed by dynamic submaximal knee extension and flexion exercises, and weightbearing exercises. In many cases, ultrasound and antiinflammatory medications were used. However, no eccentric training program was employed. gone

ment program for at least 6

t Address correspondence and repnnt requests to’ Jon Karlsson, MD, PhD, Department of Orthopaedics, Ostra Hospital, University of Goteborg, S-416 85

Goteborg,

to be

increasing either because athletes strength and speed training, or because they are receiving better medical attention.&dquo; As there are only a few previous reports in the literature, and controversy remains over the optimal treatment of partial ruptures of the patellar ligament, we find it important to present our results after surgical treatment in these patients. We are, however, well-aware that this injury should first be treated by a nonsurgical program. Only if such a seems

participate

Sweden.

403

404

TABLE 1

Sports activity in patients with partial patellar ligament rupture

TABLE 2 Classification of symptoms

SURGICAL PROCEDURE The operation is done with the patient lying supine and is performed under tourniquet control. A longitudinal skin incision is made, the paratenon is split longitudinally, and then the tendon is entered. In all of our patients, we found abnormal changes in the ligament near the bone-ligament junction at the distal pole of the patella. The size of the abnormality varied from a few millimeters to more than 1 centimeter. The abnormal tissue has softer consistency and is light yellow-brown in color, in sharp contrast to the surrounding healthy, white ligamentous tissue. The normal fiber structure of the ligament is replaced by a homogenous, nonfibrous tissue (Fig. 1). Radical resection of this homogenous tissue to normal tissue is done longitudinally, whereafter the resection surfaces are carefully closed with resorbable sutures. The ligament is closed to reduce the risk of postoperative bleeding, and subsequent postoperative scar building. The paratenon is left open. In our study, calcifications in the ligaments of two patients were also removed. When the lesion is at the ligament-bone interface, bony curettage is carried out (Fig. 2). Postoperatively, the leg is immobilized in a knee plaster cast for 4 weeks, allowing axial weightbearing and isometric quadriceps exercises. After this period of immobilization, the rehabilitation program is continued with range of motion training and isometric quadriceps exercises, with progressive increase of weight. Isokinetic training is started when at least 90° of knee motion is achieved. Return to sports activities is allowed approximately 16 weeks after surgery, providing the patient is free of symptoms and has at least 90% quadriceps and hamstrings strength compared to the uninjured leg. If, however, the patient has not met this criteria by 12 weeks after surgery, the return to sports

Figure 1. After longitudinal splitting of the patellar ligament, the site of the partial rupture is seen as a devitalized structure with a slight change of color.

Figure 2. After radical resection of the devitalized tissue, normal structure is seen on the edges of the ligament. delayed. Return to sports activity was then dependent upon the progress of the individual patient. activities is

RESULTS The results were evaluated according to the assessment table by Kelly et al.,6 with minor modifications (Table 3). We also evaluated return to sports activities, subjective and objective status. For functional assessment we used Lysholm’s knee score.’ We also did an objective evaluation with Cybex II dynamometer measurements of isometric strength of the quadriceps and hamstrings muscles in 30 and 120 deg/sec.

405

TABLE 3

Classification of functional and clinical results

Quadriceps and hamstrings strength ratios

were calculated reference. The results were excellent or good in 71 of 78 patients (91% ), but fair or poor in 7 (9%). The patients with fair results had fewer complaints than preoperatively, but complained of moderate pain during activities and were unable to return their preinjury level of sports activity. The patients with poor results had constant pain during sports activities, and were forced to stop all participation. However, patients were free of symptoms at rest. The average time for return to sports activities was 16 weeks after surgery. Only seven patients were forced to reduce their level of involvement in sports activities, as compared to the preinjury level. The average Lysholm’s knee score at follow up was 95 points (range, 74 to 100 points). Only seven patients, those same patients who could not return to the preinjury level of sports activities, had a score lower than 84 points (fair/poor result). Cybex II evaluation of thigh strength consisted of measuring quadriceps and hamstrings peak torque in a low angular velocity (30 deg/sec) and in a higher angular velocity (120 deg/sec). The uninjured leg was estimated as having normal strength, and the results were reported as a percentage of the quadriceps and hamstrings strength of the normal leg. There was a correlation between a low Lysholm score and low quadriceps strength (less than 80%) in a low angular velocity, but not in a higher angular velocity. No such correlation was found between the Lysholm’s score and the hamstring strength. As no correlation was found at the high angular velocity, this probably has no clinical relevance. The only surgical complications that were seen were two instances of superficial wound infection. Both infections healed during the immobilization time and had no bearing on the end results. The seven patients with unsatisfactory results have been evaluated carefully, but no clear explanation for their results can be found. However, some items are noteworthy. Their histology was no different from the other patients. These patients were among the older ones in the group and had had ongoing symptomatic complaints for 1 to 10 years. Four of these patients have had repeat surgery; all of them still had abnormal tissue changes in the patellar ligament. There may have possibly been an inadequate resection of the abnormal tissue. Only one of these patients gained a satisfactory result after the second operation, but the other three had no change of symptoms. We have no explanation for the poor results after reoperation.

using the healthy leg

DISCUSSION

as a

It is believed that a certain amount of degeneration occurs prior to a tendon or ligament rupture, regardless of whether it is a minor or a major rupture.6, 12 Jumper’s knee has been defined as a chronic overload lesion in the ligament near the patellar insertion, and may occur where degeneration is not very likely to be present, such as in young athletes. Evidence of tissue injuries are found at operation, with disorganization of the collagen fibers, proliferation, and neovascularization. Total rupture (Blazina Stage IV)2 represents the end stage of jumper’s knee, i.e., the major factor leading to rupture is devitalization from repetitive microtrauma (microruptures). Histologic tissue changes after repetitive microtrauma have been noticed by several authors.1,3 13 Partial ruptures can occur after repetitive strain on the extensor mechanism (microruptures), but also in sports with heavy, explosive strain (macroruptures). However, complete rupture of the patellar ligament is rare,’ and is usually seen in young athletes or patients with systemic diseases.9 We have seen partial patellar ligament ruptures both in athletes who perform repetitive activities with stress on the extensor mechanism, and those who perform more explosive activities, such as jumping, bending, or cutting. In all of our patients the abnormal tissue changes were found in the upper part of the ligament, starting near the bone-ligament junction at the distal patellar pole. This is probably due to the high stress concentration at the bone-ligament junction, where the increased tension load during eccentric work can lead to partial rupture of the area where the stress concentration is highest. In addition, the tissue abnormalities varied in length from 5 to more than 20 mm. We suggest that as the abnormal changes are microscopically found in the patellar ligament and the bony changes on the patella, the surgery should be directed toward the patellar ligament

rather than the bone. This is in agreement with the results of others.11 The mean age of the patients in this study at operation was 25 years. This may seem rather high, but only five patients were older than 30 years (three were not active in sports). Most of the patients were symptomatic for several years

prior to

surgery.

We feel that conservative treatment should be employed in patients with this type of injury before deciding upon surgery. It is our experience that about one of three patients with partial patellar ligament rupture will be in need of surgery. Surgery is only indicated when rest and other

406

conservative measures fail. Current practice prescribes that the treatment program includes specific eccentric strength rebuilding exercises in order for the healing tendon to be adequately rehabilitated.7,15-17 Stanish et al. 15 had a 90% rate of excellent or good results with an exercise program based on eccentric loading in patients with chronic inflammation. However these patients had not responded to other treatment modalities, including rest, stretching, ultrasound, and corticosteroid medication. In our study, the preoperative training program consisted basically of submaximal exercises. It is thus probable that if an eccentric loading training program had been used, the conservative treatment results would have been better, lessening the need for surgery. If surgery is necessary to correct this problem a variety of surgical procedures is available.2 These include drilling the

involved patellar pole in an attempt to increase the blood flow to the injured area,14 resection of the inferior nonarticular patellar pole with reattachment of the ligament, retinacular reinforcement, and removal of the calcified portion of the tendon.’ Other procedures involve excision of the degenerated, devitalized ligamentous tissue and reinsertion of the ligament after resection of the lower pole of the patella,&dquo; and excision of the degenerated portion of the patellar ligament,lo,11° 13 vastus medialis obliquus advancement, and lateral release in combination with drilling, scarification and removal of the distal part of the patella, including reinsertion of the patellar ligament to the patella.4 All of these procedures are considerably more complicated than the relatively simple surgical procedure described in

Figure 3. Soft tissue radiographs of partial rupture of the patellar ligament. The ligament is thicker and the distinction of the posterior edge of the ligament to the surrounding tissue reveals inflammation and edema. These two figures show the left and right knee of the same patient, with unilateral partial ligament rupture. A, normal patellar ligament, with a sharp distinction of the posterior edge to the surrounding tissue. B, partial patellar ligament rupture.

407

4. Ultrasound investigation (7.5 MHz probe) shows that the ligament with the partial rupture is thicker than the normal A, longitudinal view of normal left ligament. B, longitudinal view of the right ligament with partial rupture. C, Transverse view 1 cm below the patella, normal ligament. D, transverse view 1 cm below the patella in a patient with a partial ligament rupture.

Figure one.

study, and they have a higher risk of complication and longer period of rehabilitation. The results of this simple procedure described here were satisfactory in the majority of our patients. Postsurgery, the patients’ knees were immobilized in a plaster cast for an average period of 4 weeks. If the ligament is split longitudinally, there is probably no need for plaster immobilization during the postoperative period, as this will delay the start

this a

a rehabilitation program. Partial rupture of the patellar ligament is an important differential diagnosis of anterior knee pain. A history of sudden or insidious onset of pain may indicate a microrupture or macrorupture, respectively. The exact diagnosis may be difficult to determine in many patients. In our experience,

of

soft tissue

radiographs (Fig. 3), when compared to the uninjured side, may give some information about the state of the injured patellar ligament. With partial ligament rupture, the ligament is thickened and there is no visible distinction between the posterior edge of the ligament and the surrounding tissues, indicating inflammatory changes and edema in the ligament. Ultrasound investigation with a 7.5 MHz transducer will reveal thickening of the ligament both in the longitudinal (Fig. 4, A and B) and the transverse plane (Fig. 4, C and D). For preoperative diagnosis we routinely used soft tissue radiographs and relied on ultrasound investigation later in the study. At the time of the study, computerized tomogra-

408

phy and magnetic resonance imaging were us and, therefore, were not used.

not available to

REFERENCES 1

2

CONCLUSIONS

3. 4

partial rupture of the patellar ligament, or jumper’s knee, is recommended only if a prolonged and well-supervised conservative treatment program fails. In this study, our surgical procedure was careful resection of the abnormal tissue after longitudinal splitting of the ligament. Excision of the damaged, devitalized tissue probably reduces inflammation and edema at the bone-ligament junction, causing less disturbance of the microcirculation. As the degenerated portions of the tendon are removed, there is relief from pain. The overall results were comparable to previous reports. As no bony procedure is performed, the postoperative rehabilitation is easier to do. We emphasize, however, that patients should not return to sports activities until both the quadriceps and hamstring strengths are over 90% of that of the uninjured side. We conclude that the majority of patients who have jumper’s knee with chronic patellar ligament inflammation or partial rupture, and who are not helped by conservative treatment, will benefit by the surgical procedure we suggest here, and by careful postoperative rehabilitation. More complex surgical procedures should be used only when there is an extensor mechanism malalignment to be corrected. Surgical

treatment for

5

6 7

8

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Maddox PA, Garth WP Tendinitis of the patellar ligament and quadriceps (jumper’s knee) as an initial presentation of hyperparathyroidism J Bone Joint Surg 68A 288-292, 1986 10 Martens M Tendinitis of the patellar tendon Acta Orthop Belg 48 45311 12

13 14 15 16

17 18

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