Knee sliced open by skate blade: complete patellar tendon rupture in an elite long track speed skater

Abstract

A long track speed skater sustained a deep horizontal cut to the right knee just distally to the patella, after he got hit by the skate blade of the pair mate. The injury included a complete patellar tendon rupture from the apex of the patella, a 1 mm deep transverse cut in the femoral condyle and a partial rupture of the anterior cruciate ligament. The tendon rupture was repaired with transosseous suture repair without augmentation. A knee brace was used for 8 weeks, with a gradual decrease in flexion restraints. A rehabilitation programme was overseen by a dedicated physiotherapist. At 6 months, he started a gradual return to skating sessions. After 1 year, he had symmetrical single-legged hop performance, but quadriceps weakness due to pain. The patient returned to competition speed skating at national levels after 11 months, and within the first postoperative year, he was breaking new personal records on the ice.

Background

Acute patellar tendon ruptures are infrequent injuries. It is the third most common injury of the extensor apparatus of the knee, after quadriceps tendon ruptures and patella fractures.¹ Surgical treatment is primary repair with transosseous sutures^2–7 or suture anchors.^8–10 A reinforcement of the suture complex is commonly used with either a non-organic material, such as a cerclage wire,5 6 9 11–13 strong sutures,^{4 11 14} synthetic material^{3 15} or autologous grafts, such as semitendinosus tendon.^{7 14 16} We describe an open, traumatic patellar tendon rupture in a young professional speed skater, treated with transosseous suture repair without augmentation.

Case presentation

A long track speed skater was competing at the Norwegian National Championship at the time of the occurrence. The incident was covered by Norwegian TV and in printed media.¹⁷ The accident happened when the pair skater, who raced in the inner lane, fell and hit the padding, and then bounced back into the outer lane. He collided with the patient in approximately 50 km/hour (30 mph). He hit the patient’s right knee with the blade of one of his skates, causing a deep laceration distally to the patella. The wound bled profoundly, and first aid with compression was provided on site. The patient was then taken to an orthopaedic trauma centre.

Investigations

The distal neurovascular condition was normal on admission. Plain radiographs of the right knee showed a high riding patella. The patient was taken to operating theatre for wound exploration under general anaesthesia. He was given prophylactic cefazolin. The findings were a proximal full thickness rupture of the patellar tendon, a partial tear of the anterior cruciate ligament and a 1 mm deep transverse cut in the cartilage of the non-weight bearing part of the femoral condyle (figure 1). The anterior drawer test was negative and the anterior cruciate ligament was considered functionally intact.

Figure 1.

The injury included a proximal full thickness rupture of the patellar tendon (a), a partial tear of the anterior cruciate ligament (b) and a 1 mm deep transverse cut in the cartilage of the non-weight bearing part of the femoral condyle (c).

Treatment

The patellar tendon was repaired using non-absorbable braided sutures (Ti-Cron no 5; Medtronic, Minnesota, USA) with Krackow whip stitch technique and transosseous reinsertion using a 2.5 mm drill bit through the patella. An absorbable synthetic suture (Polysorb 2.0; Medtronic, Minnesota, USA) was used to further approximate the ruptured ends (figure 2). The suture complex proved patent at knee flexion of 45° and a suture or cerclage wire augmentation was considered unnecessary. The subcutaneous tissue and skin were then sutured in a layered fashion. A knee brace locked in full extension was to be used for 8 weeks, with a gradual increase of flexion after 4 (0–30°) and 6 (0–60°) weeks. Weight-bearing was only allowed in full extension. A dedicated physiotherapist was monitoring his rehabilitation period. In the initial phase, he performed isometric strengthening exercises with a special focus on quadriceps muscle activation. After 8 weeks, he regained full range of motion. Biking sessions were performed 3–5 times per week. After 3 months, a more intense neuromuscular exercise programme was initiated, and the resistance in isotonic quadriceps and hamstring strength exercises was gradually increased. The resistance and intensity were adjusted according to the presence of anterior knee pain. Knee pain was monitored with a visual analogue scale from 0 (no pain) to 10 (worst possible pain). The highest level of allowed pain with exercise was 5. In the later phases, he performed a skate-specific strength and conditioning programme until he returned to skating.

Figure 2.

The patellar tendon was repaired using non-absorbable braided sutures (Ti-Cron no 5; Medtronic, Minnesota, USA) with Krackow whip stitch technique. An absorbable synthetic suture (Polysorb 2.0; Medtronic, Minnesota, USA) was used to further approximate the ruptured ends.

Outcome and follow-up

The patient had full range of motion 8 weeks postoperatively. To quantify the function of the knee after the tendon rupture and surgery, concentric knee extensor and flexor muscle strength were measured at 60° per second with a Biodex 6000 isokinetic dynamometer (Biodex Medical System, Shirley, New York, USA) (figure 3). From 6 to 12 months postoperatively, he improved the knee extensor strength of his involved leg with 86.6% (table 1). At both 6 months and 1 year postoperatively, he had substantially lower knee extension strength in the injured leg compared with the uninjured leg. Both tests were, however, limited by anterior knee pain during testing. The single hop for distance was conducted at 5, 9 and 11 months postoperatively (table 2). From 5 to 11 months postoperatively, he improved the distance hopped on his injured leg with 54.3%. The limb symmetry index was 94%, 11 months postoperatively, which is satisfactory for a return to sports.¹⁸ Patient-reported functional status was assessed at 6 months and 1 year postoperatively with the Knee injury and Osteoarthritis Outcome Score (KOOS) (table 3). The change in KOOS varied from 2.8 points worsening (KOOS pain) to 14.3 points improvement (KOOS symptoms). He reported stiffness, daily pain with moderate activity and problems with running and jumping. He experienced anterior knee pain when exposed to heavy loads while skating, up to 1 year postoperatively. The patient had a progressive return to activity and speed skating. Six months postoperatively, he was back on the ice and after 11 months, he was again competing at a national level. After 1 year, we conducted an MRI scan to the operated knee and both thighs. Coronal T2-weighted images showed a slightly lower quadriceps muscle volume on the injured side with a mean value of 76.3 cm² on the injured side compared with 87.3 cm² of the non-injured side. Except for hypertrophic patellar tendon tissue, which is to be expected after surgery, the knee was without any major structural abnormal findings. The Insall-Salvati ratio was 1.1 indicating the position of patella to be within physiological range.¹⁹

Figure 3.

Concentric knee extensor and flexor muscle strength were measured at 60°/s with a Biodex 6000 isokinetic dynamometer (Biodex Medical System, Shirley, New York, USA).

Table 1.

Extension and flexion peak torque and total torque at 6 months and 1 year postoperatively

6 months postoperatively	Left	Right	Deficit (%)
Knee extension
Peak torque (Nm)	299.8	97.1	67.6
Total work (J)	1333.3	525.8	60.6
Knee flexion
Peak torque (Nm)	138.1	130.5	5.5
Total work (J)	768.4	701.6	8.7

1 year postoperatively	Left	Right	Deficit (%)
Knee extension
Peak torque (Nm)	302.4	181.2	40.1
Total work (J)	1467.0	910.9	37.9
Knee flexion
Peak torque (Nm)	139.5	137.9	1.2
Total work (J)	772.9	768.3	0.6

Pain during test: 6 for knee extension (0–10, 0=no pain, 10=worst pain).

Pain during test: 4–5 for knee extension (0–10, 0=no pain, 10=worst pain).

Table 2.

The single hop for distance at 5, 9 and 11 months postoperatively

Single hop for distance	Injured side (cm)	Non-injured side (cm)	Symmetry index (%)
5 months postoperatively	129	172	75
9 months postoperatively	186	215	86
11 months postoperatively	199	211	94

Table 3.

Patient-reported functional status was assessed 6 months and 1 year postoperatively with the Knee injury and Osteoarthritis Outcome Score (KOOS)

KOOS (0–100)	6 months postoperatively	1 year postoperatively
Pain	80.56	77.78
Symptom	57.14	71.43
Function in daily living (ADL)	86.56	86.76
Sports and recreation	40	45
Quality of life	37.5	50

Discussion

Speed skating has one of the lowest injury rates of all winter sports, and severe injuries are rare.^{20 21} Injuries typically happen when the skater falls in the curves (ie, sliding under the paddings), in collisions with competing skaters or as a self-inflicted injury (ie, the blade hits the lower extremity).²² Commonly reported injuries include fractures, ligament injuries, tendinopathies and lower back pain.²³ Lacerations to the lower extremities have been reported from time to time.^{24 25} Patellar tendon ruptures in the general population is an infrequent injury.¹ The typical patient is a male less than 40 years of age,^{8 26 27} but a recent study showed a greater age distribution with 43% of ruptures occurring in patients older than 40.²⁸ The injury mechanism is usually a forceful quadriceps contraction on a semiflexed, predisposed knee,^{1 29 30} and the majority of ruptures occur in sports.^{8 31} These tears are usually located at the level of the distal pole of the patella.²⁶ The diagnosis can be difficult in case of severe swelling,^{6 13 27} but plain lateral radiographs will show a high riding patella and disruption of the sharp and well-defined margin of the patellar tendon.¹⁹

Acute patellar tendon ruptures are usually treated surgically, with primary repair using transosseous sutures^2–7 or suture anchors.^8–10 At our hospital, transosseous sutures are the preferred surgical method for both patellar tendon and distal quadriceps tendon ruptures. It was, therefore, chosen in this case. It is a simple and low-cost surgical procedure, and historically, the method of choice for repairing proximal patellar tendon ruptures.^2–7 Interestingly, most biomechanical studies favour suture anchors over transosseous sutures.^32–34 Ettinger et al compared titanium and hydroxyapatite suture anchors with transosseous sutures in a biomechanical cadaveric study. Both suture anchors had significant less gap formation and resisted higher ultimate load to failure than the transosseous group. Common failure mechanisms were bony pullouts of the anchors, while the transosseous sutures failed due to knot failure or tendon pullout.³² In a similar biomechanical study, Bushnell et al ³⁴ compared suture anchors with transosseous sutures using FiberWire and Ethibond. Suture anchors proved at least as efficient as the standard transosseous sutures, withstanding gap formation. They hypothesised that the relatively long length of the ‘knot-tendon’ distance in the transosseous suture group contributed to the increased gap formation, and that suture anchors result in a more correct reapproximation of the tendon, restoring the anatomy. The transosseous sutures failed at the level of the knot, while the suture anchors failed by anchor pullout or by suture cut-out at the anchor eyelet. No differences were found in the ultimate failure test. Later, Bushnell et al did a retrospective analysis of 15 patients with acute isolated patellar tendon ruptures treated with suture anchors. Eleven of the patients had no postoperative complications and returned to their previous level of activity. Three patients who did not comply with load restrictions in the early postoperative phase had a re-rupture. In two cases, the suture loops were pulled out of the tendon, and one case involved breakage of the suture anchor metal eyelets. Complying with postoperative restrictions might, therefore, be the key to avoiding early failure.⁸ Smaller incisions, reduced risk of patellar fractures and intra-articular damage are other factors that favour the suture anchors over transosseous sutures.

Suture repairs are commonly augmented to avoid tendon repair failure, and to allow accelerated mobilisation.³⁵ The augmentation can be performed with a cerclage wire,5 6 9 11–13 strong sutures,^{4 11 14} synthetic material^{3 15} or autologous grafts, such as semitendinosus tendon.^{7 14 16} Novel surgical techniques have been described with the use of suture button fixation,³⁶ strong sutures only¹⁴ and a combination of different techniques.³⁷ We chose not to augment the primary tendon repair in our patient, because the repair was considered very solid when tensioned intraoperatively. We also had no suspicion of the tendon being degenerative, which increases the risk of the suture cutting out of the tendon.³⁴ Marder and Timmerman reported no re-ruptures and favourable outcomes in patients treated with only suture repair and early mobilisation.² In most biomechanical studies, however, an increased gap formation and potential tendon repair failure are seen in repairs without augmentation.^{35 38–40} Ravalin et al found an arbitrary gap formation of 5 mm or more to be the point of failure when tendon repairs are biomechanically stressed.³⁸ It is hypothesised that a gap of this size will contain more scar tissue, which is weaker and less functional than the normal tendon tissue.

In the past, patients were typically immobilised with a cast for 6 weeks.²⁷ Today, early mobilisation and gradual increase in joint motion in a hinged brace are preferred by most authors.2 4 5 8 Our patient was immobilised for 2 weeks in a hinged brace, followed by a gradual increase in flexion for a total of 8 weeks. Weight-bearing was only allowed with the knee in full extension. This is a standard postoperative procedure for repair of patellar tendon and distal quadriceps tendon ruptures, at our department. Lee et al prefer an early range of motion from 0 to 45° the first 2 weeks, followed by a weekly increase in 15° until the full range of motion is achieved. The first 6 weeks, full weight bearing is allowed with the knee locked in extension and with the use of crutches. The knee brace is discontinued after 10–12 weeks, when adequate quadriceps control is reached.⁴¹ A recent controlled laboratory animal study suggests that a period of postoperative immobilisation after tendon-to-bone repair may optimise healing, giving less scar tissue and a stronger tendon–bone interface.⁴² In a thorough systematic review, Serino et al found early postoperative mobilisation to be associated with a significantly higher adverse event rate than late mobilisation, when compared with minimum 6 weeks of immobilisation.⁴³

Our patient has anterior knee pain, especially when skating. While it is difficult to compare a professional speed skater to patients with a more sedentary lifestyle, anterior knee pain is a common problem after repair of patellar tendon rupture. All patients in the study of El-Desouky et al experienced anterior knee pain in the initial rehabilitation phase. In three patients, the pain gradually resolved beyond 6 months.⁷ Marder et al reported two patients with persistent pain, both re-operated with arthroscopic debridement of peripatellar scar adhesions.² Patellofemoral incongruity after tendon repair has been proposed to be a contributing factor to anterior knee pain.^{27 44} Overtightening of a cerclage wire could theoretically lead to a low riding patella with alterations in the biomechanics, consequently causing pain. In our patient, a cerclage wire was not used, and overtightening with suture repair alone seems unlikely. On the other hand, avoiding augmentation of the suture repair has proven to give increased gap formation,³⁸ leading to a greater deposit of non-functional scar tissue. This could alter the biomechanics of the extensor apparatus, leading to anterior knee pain. The knee sustains a tremendous load during speed skating, which will accentuate any biomechanical cause of knee pain. The MRI of our patient 1 year after the surgery showed no major signs of structural alterations. His pain is likely caused by a combination of the nature of the injury, and the load his knee is exposed to. The MRI also showed a slight atrophic quadriceps muscle on the injured side, compared with the non-injured side. As many as 75% of patients have persistent atrophy of the quadriceps muscle, but this does not necessarily affect muscle strength.²⁷ The fact that our patient returned to competing at the highest level, breaking new personal records, suggests that his quadriceps strength is sufficient for his demanding sport.

Patient’s perspective.

The accident occurred in January 2017 while I was competing in the Norwegian speed skating sprint championship. During the last distance (1000 m), my opponent fell 30 m in front of me, hit the safety rig around the track and was thrown back into my lane where I ran over his skate, and which cut my knee open. Laying on the ice with my leg up, people ran over to help and to see what was going on. Some medical experienced parents of other skaters helped by compressing the bleeding wound until the ambulance arrived.

I left the hospital 1 week after surgery with crutches and a shin guard with limited possibility to bend my knee. Some weeks passed by and I gradually started bending my knee to 30° and later to 60° and 90° of flexion. I was told from the doctors that the injury would not affect my professional career as an athlete if the rehabilitation was done correctly and I might be able to skate again after 6–8 months.

The following months contained hours of simple training exercises to get my leg started and a lot of rest. I was in contact with the doctors at the hospital for regular check-ups and I had physiotherapy 2–3 times a week. I gradually became stronger in my thigh where the most muscle loss had been, and after 3 months, I could start more specific strength training and biking. These two training methods became central for my recovery and helped building fitness, stability and strength. After 6 months, I returned to ice sessions and I could slowly start to move around and feel how it was to skate again. Gradually, I was able to bend my knee to which I could return to a speed skaters position. During the next months, I continued training and increased the duration and numbers of session to about 15 hours/week on an average. Slowly, I could skate more and more and push the knee harder without too much pain. Eleven months later, I did my first competition and at the end of the 2017/2018 season, I improved my personal records in every distance (from 500 to 10 000 m). As an example, I improved the 5000 m time from 7.28.29 to 7.07.87, and which I am very satisfied with when losing so much important training post injury.

This injury is not very common and shocked the whole speed skating community in Norway. I think I got some of the best follow-up to get me back out on the ice, and without thorough rehabilitation, I would never get back so fast. Today, I still struggle with knee pain mostly when exercising, but I’m focused on getting into a new season of skating with a full year of training and preparations.

Learning points.

• Speed skating has one of the lowest injury rates of all winter sport, with lacerations to the lower extremities reported from time to time

• Acute patellar tendon rupture is an infrequent injury, and is usually treated surgically with primary repair using transosseous sutures or suture anchors

• Return to elite level speed skating and previous level of performance is possible approximately 1 year after a deep knee laceration and patellar tendon rupture.

• Residual pain and stiffness may last longer than 1 year.