Reconstruction of the posterior cruciate ligament for isolated injuries of the posterior cruciate ligament: A myth or reality?

Reconstruction of the posterior cruciate ligament for isolated injuries of the posterior cruciate ligament: A myth or reality?

                                         Dr KS Dhillon FRCS, LLM

Posterior cruciate ligament (PCL) injuries result from a posteriorly directed force applied to the proximal tibia, unlike anterior cruciate ligament (ACL) injuries which result from non-contact rotational forces. Injuries to the PCL are believed to be rare as compared to ACL injuries. The true incidence of PCL injuries is unknown partly because these injuries are easily missed and some patients may not seek treatment because symptoms associated with PCL injuries are less disabling as compared to symptoms associated with ACL injuries. However the incidence of PCL injuries has been reported to vary from 1% to 47% of all ligament injuries of the knee (1). There have been suggestions that only about 40% of PCL injuries are isolated injuries and rest are usually combined ligamentous injuries (2). The ideal treatment of PCL injuries according several authors remains controversial (2-4).

Is treatment of PCL injuries controversial or are there some conflicts of interest involved in the treatment of patients with PCL injuries which makes surgeons promote surgical reconstruction of the PCL for such injuries?

Treatment of isolated PCL injuries

There is no controversy about the treatment of PCL avulsion fractures, which are ideally treated by open reduction and internal fixation when the fragment is large enough to be fixed with a screw. Isolated injuries of the PCL usually produce a grade I to II posterior laxity of the knee while a grade III laxity is produced by a combined PCL and posterior lateral corner injuries. What is the best method of treatment of isolated PCL injuries?

An acute mid-substance tear of the PCL may heal (5) unlike ACL mid-substance injuries which do not heal. Logically such injuries should be treated conservatively. The long term natural history of isolated PCL injuries suggests that there is no indication for surgical treatment of such injuries because the outcome of conservative treatment is good. There are no studies to show that surgical treatment is better than conservative treatment for isolated tear of the PCL. Neither is there any evidence that surgical treatment reduces the incidence of osteoarthritis of the knee after PCL injuries (4).

Natural history of isolated PCL injuries

One of the earlier studies of the long term outcome of non-operatively treated isolated PCL injuries was done by Parolie and Bergfeld in 1986 (6). They studied 25 patients who were treated conservatively for isolated PCL injuries and followed-up for a mean of 6.2 years (2.2 to 16 years). They found that 80% of the patients were satisfied their knee and 84% had returned to their previous sport, with 68% at same level of performance and 16% at a reduced level of performance. Patients who were satisfied with their knee and had returned to sports had quadriceps strength of more than 100% of the contralateral uninvolved knee and those who were dissatisfied with their knee and not returned to sports had less than 100% strength of the quadriceps as compared to the contralateral knee.

Selbourne et al (7) prospectively studied the natural history of acute, isolated, non-operatively treated PCL injuries in athletically active patients. The study included 133 patients all of whom completed a yearly questionnaire for an average of 5.4 years (2.3 to 11.4 years) and 51% of the patients (68 out of 133) returned for long-term clinical and radiological examination. The functional outcome was good with a mean modified Noyes knee score of 84.2 points, a mean Lysholm score of 83.4 and a mean Tegner activity score of 5.7.The grade of laxity had no correlation with subjective functional outcome. Fifty percent of the patients returned to the same sport at the same or higher level of performance, one third (33.3%) returned to same sport at a lower level and one-sixth (16.6%) did not return to the same sport.

The authors concluded that ‘athletically active patients with acute isolated posterior cruciate ligament tears treated nonoperatively achieved a level of objective and subjective knee function that was independent of the grade of laxity’.

The longest follow-up study of patients with acute, isolated PCL injuries treated non-operatively was reported by Shelbourne et al in 2013 (8). The study included 68 patients who had a subjective follow-up at a mean of 17.6 years and 44 of the patients had a subjective and objective follow-up at a mean of 14.3 years (10-21 years). The mean quadriceps strength was 97% of the contralateral side and the range of knee motion was normal in all patients.

Fifty percent of the patients had no osteoarthritis (OA) of the knee, 30% had mild OA, 9% (4 patients) had moderate and 2% (1 patient) had severe OA of the knee at a mean follow-up 14.3 years. The mean IKDC (International Knee Documentation Committee) and modified CKRS (modified Cincinnati Knee Rating System) subjective scores were 73.4 ± 21.7 and 81.3 ± 17.4, respectively at 17 years follow-up and the subjective scores did not correlate with the degree of PCL laxity.
The authors concluded that long term follow-up of patients, with isolated PCL injuries treated non-operatively, shows that patients remain active, have good muscle strength, full range of knee motion and they report good subjective scores and that the incidence post-traumatic OA is low.

In 2007 Patel et al (1) published a study involving 57 patients with acute isolated PCL injuries who were treated non-operatively with a mean follow up of 6.9 years (2 to 19.3 years). Seventeen patients (29.8%) had a grade I and 41 patients (71.9%) had a grade II laxity of the PCL. The functional outcome at 7 years was good with a mean Lysholm-II knee score of 85.2 points (range 51 to 100 points) and a mean Tegner activity level of 6.6 (range 3 to 10). The Lysholm-II knee scoring system, showed excellent results in 40%, good in 52%, fair in 3%, and poor in 5% of the knees. The incidence of mild medial compartment OA was 12% and moderate medial compartment OA 5% and none of the patients had severe OA.

These medium and long term studies of the natural history of isolated PCL injuries reveal that the subjective functional outcome is good, without surgical intervention, with majority of the patients returning to their pre-injury activity level. Are the results of PCL reconstruction better than conservative treatment?

Surgical treatment of isolated PCL injuries

Most of the published studies reporting the outcome of PCL reconstruction for isolated PCL injuries are small case series with a short follow-up, and the heterogeneity of the patients studied and the technique used make it difficult to judge outcome in these patients(3).
However there are two studies that have reported the long term outcome of PCL reconstruction in patients with isolated PCL injuries.

Herman et al (9) studied 25 patients (22 male, 3 female) with an average age of 30.8 years who underwent single bundle PCL reconstruction for pain and functional instability of the knee. The mean follow-up was 9.1 years (6.5 to 12.6 years). Twenty two patients were evaluated clinically and 3 patients provided telephone interviews.

The final mean IKDC score was 65, Lysholm score was 75 and the VAS (visual analogue score) was 8. The functional scores were fair to good and were significantly better than the pre-operatively scores. The final Tegner score was 5.7. The functional results were significantly better in patients with no cartilage damage at the time of surgery and in those who underwent surgery within 1 year post injury.

Jackson et al (10) evaluated the long term outcome of PCL reconstruction in 26 patients after failed conservative treatment. At 10 years follow-up the IKDC score was 87 and the Lysholm score improved from 60 to 90 post-operatively. Twenty two patients had radiological examination and 18% of the patients had grade II OA changes and another 18% had grade III OA changes.
A careful analysis of the subjective outcome reported by Shelbourne (7) and Patel (1) for non-operative treatment and that by Herman (9) and Jackson (10) for surgical treatment of PCL injuries appears to be very similar.

Complications of PCL surgery

PCL injuries are rare and the indications for surgery of the PCL are limited since conservative treatment has good outcome, therefore the number of PCL surgeries carried out by surgeons per year are small. This limited experience with such complex surgery can lead to a higher incidence of complications especially when there are vital neurovascular structures at the back of the knee. Furthermore catastrophic complications usually never get reported which can give surgeons a false sense of relative risks involved when undertaking such procedures.

Besides the standard complications, such as those associated with anaesthesia and complication of surgery such as infections and thromboembolic complications which can occur with any orthopaedic procedure, there are specific complications associated with PCL surgery, some of which includes neurovascular injury, osteonecrosis, fractures, stiffness, residual laxity and anterior knee pain.
A survey of frequency of complications associated with arthroscopic surgical procedures of the knee reported by Salzler et al (11), where the data was obtained from the ABOS (American Board of Orthopaedic Surgery) data base, showed that the complication rate was the highest for PCL surgery as compared with other arthroscopic procedures. The complication rate for PCL surgery was 20.1%, ACL surgery 9.7%, meniscal repair 7.7%, menisectomy 2.8% and chondroplasty 3.5%. The overall pulmonary embolism rate was 0.11% and the infection rate 0.84%. These were self-reported complication rates and the authors believe that the actual rates may be higher.

Conclusion

The outcome of non-operative treatment for isolated mid-substance PCL injuries is good as has been revealed by long term studies of the natural history of such injuries. The results of surgical reconstruction of the PCL are not superior to that of non-operative treatment and PCL surgery can be associated with complications which would not be seen with conservative treatment. Hence there appears to be no indication for PCL reconstruction for intra-substance tears of the PCL.

References

1. Patel DV, Allen AA, Warren RF, Wickiewicz TL, Simonian PT. The Nonoperative Treatment of Acute, Isolated (Partial or Complete) Posterior Cruciate Ligament-Deficient Knees: An Intermediate-term Follow-up Study. HSS J. 2007 Sep; 3(2): 137–146.

2. Clancy WG Jr, Sutherland TB. Combined posterior cruciate ligament injuries. Clin Sports Med 1994; 13(3):629–647.

3. Montgomery SR, Johnson JS, McAllister DR, Petrigliano FA. Surgical management of PCL injuries: indications, techniques, and outcomes. Curr Rev Musculoskelet Med. 2013 Jun; 6(2): 115–123.

4. Dowd GSE. Reconstruction of the posterior cruciate ligament: Indications and results. J Bone Joint Surg [Br] 2004; 86-B: 480-91.

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

6. Parolie JM, Bergfeld JA: Long-term results of nonoperative treatment of isolated posterior cruciate ligament injuries in the athlete. Am J Sports Med 1986; 14:35-38.

7. 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.

8. Shelbourne KD, Clark M, and Gray T. Minimum 10-Year Follow-up of Patients after an Acute, Isolated Posterior Cruciate Ligament Injury Treated Nonoperatively. Am J Sports Med July 2013 vol. 41 no. 7 1526-1533.

9. Hermans S, Corten K, Bellemans J. Long-term results of isolated anterolateral bundle reconstructions of the posterior cruciate ligament: a 6- to 12-year follow-up study. Am J Sports Med. Aug 2009; 37(8):1499-507.

10. Jackson WF, van der Tempel WM, Salmon LJ, Williams HA, Pinczewski LA. Endoscopically-assisted single-bundle posterior cruciate ligament reconstruction: results at minimum ten-year follow-up. J Bone Joint Surg Br. 2008 Oct; 90(10):1328-33.

11. Salzler MJ, Miller CD, Lin A, Irrgang JJ, Harner CD. Complications Following Arthroscopic Knee Surgery. Orthopaedic Journal of Sports Medicine, September 2013 vol. 1 no. 4 suppl 2325967113S00044.

Treatment of ACL injuries: Unsettled controversies

                             Treatment of ACL injuries: Unsettled controversies

                                               DR KS Dhillon, FRCS, LLM

Conflicts of interests in medicine and healthcare have over the last few decades become universal with ‘undue influence distorting healthcare services, strategy, expenditure and practice’ and there is an ‘urgent need for regulation and other action towards redefining the mission of medicine towards a more objective and patient-, population- and society-benefit direction that is free from conflict of interests’ (1).

Conflicts of interest prevent many from changing their standard of care for patients even when high level well designed randomised trials are published. They ‘continue to write rebuttal and editorials in defence of their specialities instead of doing the right thing which would be to ‘abandon ship’’ (2).

In 2010 Frobell et al published (New England Journal of medicine) a well conducted level I randomised study comparing conservative with surgical treatment of ACL injuries in a young Swedish population. The conclusion of study was ‘in young, active adults with acute ACL tears, a strategy of rehabilitation plus early ACL reconstruction was not superior to a strategy of rehabilitation plus optional delayed ACL reconstruction. The latter strategy substantially reduced the frequency of surgical reconstructions’ (3).

This article in July 2010 was followed by two correspondences in the Nov issue of the same journal questioning the validity of the conclusions (4). In the Feb 2011issue of Arthroscopy Journal the editors of the journal in an editorial entitled ‘Prompt operative intervention reduces long-term osteoarthritis after knee anterior cruciate ligament tear’ in which the editors labelled the conclusions as a ‘spin’ (5).

 Does ACL reconstruction reduce the incidence of OA and what is the outcome of treatment of ACL injuries is the real question.

Outcome of treatment

Does reconstruction of the ACL minimise the risk of future complication and improve quality of life? Dunn et al (6) in a study involving 6,576 active-duty army personnel showed that ACL reconstruction was protective against meniscal and cartilage injury. The study group had 3,795 subjects (58%) who had an ACL reconstruction and 2,781 subjects (42%) who were treated conservatively. Of those treated conservatively 32.6% underwent reoperations (meniscal, cartilage, ACL reconstruction surgery) as compared 12.7% reoperations (meniscal and chondral surgery) in the ACL reconstruction group. Subsequent ACL reconstruction was done in 26% of the patients who were initially treated conservatively. This retrospective follow up study as the authors admit has a selection bias. The authors were of the opinion that a randomised clinical trial to study the preventive benefits of ACL reconstruction would not be feasible ‘because of lack of equipoise’ but now they have been proven wrong.

Frobell et al (7) have now published a five year outcome of a randomised trial for the treatment of acute anterior cruciate ligament tear. This level 1 scientific study compared the mid-term (5years) patient reported and radiographic outcomes between those patients treated with rehabilitation plus early ACL reconstruction and those treated with rehabilitation and optional delayed ACL reconstruction. The cohort was 121 young active adults with a mean age of 26 years who had an acute ACL injury to a previously uninjured knee. All patients had similar structured rehabilitation and 62 patients were assigned to early ACL reconstruction while 59 were assigned to an option of having a delayed ACL reconstruction if the need arises. One patient was lost to follow-up at 5 years. They studied the 5 year outcome from baseline of the mean value of four out of five subscales of the knee injury and osteoarthritis outcome score (KOOS), the absolute KOOS (all five subscales), SF-36, Tegner activity scale, meniscal surgery, and radiographic osteoarthritis.

 In the group of patients treated conservatively 51% of the patients needed a delayed ACL reconstruction. However all the outcome measurements were the same in the group treated conservatively and the group treated with ACL reconstruction. The meniscal surgeries rates, radiographic osteoarthritis and all functional scores were the same in both groups. The results were hence the same in patients treated conservatively, and those treated with early or delayed reconstruction of the ACL. The authors concluded that these results should encourage clinicians and young active adults to consider rehabilitation as the primary mode of treatment for an acute ACL tear. In other words about 50% of the patients will not need an ACL reconstruction if they are treated with structured rehabilitation. If we follow the prevailing advice that all young active patients should have reconstruction of the ACL (8), about 50% would be having unnecessary surgery. This study however does not apply to professional athletes as well as to patients who are involved in less than moderate activity.

The outcome of the findings in this first ever level 1 study has not got everyone taking solace in the fact that 50% of the patient did not need a reconstruction of the ACL, since a commentary in the Journal of Bone and Joint Surgery (9) suggest that the results are open to interpretation and that some may ask if 50% of the patients will need subsequent surgery, ‘why wait’. The logical answer would be that waiting will prevent unnecessary surgery and possible complications in 50% of the patients and not to mention the financial savings which would substantially be more now than the figure of $ 1 billon going by the year 2000 estimate in the US (8).

The frequency of delayed reconstruction of ACL after initial conservative treatment in this study of young active individuals by Frobell et al is high compared to other studies (10). Other studies have reported frequencies that range from 16% to 35% but these studies are not comparable because of the nature of the study, patient selection, criteria for surgery, the nature of surgery and treatment.

A reflection of the number of patients who will need a delayed reconstruction of the ACL in a general population is provided by a level 2 study by Neuman et al (11). They followed up 100 consecutive patients with a complete tear of the ACL, which was confirmed by arthroscopy, for 15 years. All patients were treated conservatively with rehabilitation. The study excluded those who participated in professional sports and were unwilling to reduce their activity level. They found that 23% of the patients required a delayed reconstruction of the ACL between 6 months and 11 years. This would translate to 77% of patients not requiring an ACL reconstruction at 15 years follow-up.

Return to sports

In the past reconstruction of ACL has been advocated as a requirement for return to competitive sports after a tear of the ACL. Ardern et al (12) have done a systematic review and meta-analysis to determine post-operative return to sports outcomes after ACL reconstruction surgery. Their review found that although 90% of the patients achieved successful surgical outcome in terms of impairment based measurement of knee function and a 85% successful activity based outcome, only 44% of patients returned to competitive sport and approximately 63% of patients returned to pre-injury level of sports participation.

Swirtun et al (13) in a study involving 46 patients aged between 18 and 50 years, with an acute unilateral ACL tear, where the treatment was self- selected by the patient to have conservative treatment or reconstruction of the ACL, found no difference in activity level at a 5.6 years follow up. In this study 24 patients had conservative treatment and 22 had an ACL reconstruction. In fact the conservative group had a significantly better outcome in the knee related QOL domain of the KOOS than the patients with ACL reconstruction.

The study by Frobell et al (7) showed a modest return to pre-injury activity level at 5 years after a tear of the ACL and there was no difference between the groups treated with early ACL reconstruction, delayed ACL reconstruction or those treated with rehabilitation alone.

Secondary meniscus injury

Early ACL reconstruction is recommended to minimise the risk of meniscal tears. Church et al (14) in a retrospective review of 183 patients compared the incidence of meniscal tears in patients who underwent ACL reconstruction early (within 12 months of injury) and those who underwent reconstruction late (after 12 months). They showed that the incidence of meniscal tear was higher in the late reconstruction group (71.2 % versus 41.7%). They recommended early surgery to prevent meniscal injury. This study was not a randomised study comparing early with late reconstruction and the numbers in each subgroup were small for statistical comparison.

A level 4 case series by Yoo et al (15) also showed an increased likelihood of medial meniscus tear when ACL reconstruction was delayed. This study involved a highly selected group of patients. They selected 31 patients from among 311 patients who had concurrent meniscal repair and ACL reconstruction. The selection criteria was availability of two MRI studies, one at the time of injury and another at a later date when the patient opted for a delayed ACL reconstruction. They showed that the incidence of medial meniscus injury in patients with chronic ACL deficiency increased from 55% at the first MRI studies to 84% at the second MRI studies. The mean between-study time was 36.8 months. Papastergiou et al (16) in retrospective study of 451 patients showed that the prevalence of meniscal tears is significantly higher if ACL reconstruction is delayed for more than 3 months.

These are retrospective observational studies with compromising interpretation of their findings (7). The real frequency of secondary meniscal injury or meniscal surgery is not known. The first and only high quality randomised control trial done by Frobell et al (7) showed that there was no statistically significant difference in the number of knees having meniscus surgery over a 5 years follow up after an ACL injury, between groups treated with rehabilitation, early ACL reconstruction or delayed reconstruction. Time to event analysis of proportion of meniscus treated with surgery also did not show any difference between the groups. In the past it was believed that reconstruction of the ACL reduces the risk of meniscal tears but this study did not show that reconstruction of the ACL reduces the risk of meniscal tears or not reconstructing the ligament increases the prevalence of meniscal tears.

Complications and long term failures of ACL surgery

As with any surgery complications can and do occur in patients undergoing ACL surgery. Some of the complications reported include, infection, graft failure, loss of knee motion, patellar pain, patella fractures and thromboembolic events. However the complication rates are low. Wound complications within 30 days occur in about 0.75%, readmission within 30 days in 1.36%, VTE in about 0.44% and PTE in about 0.18% of the patients (17). 

Long term failures of ACL reconstruction

Crawford et al (18) did a systematic review of long term failures of ACL reconstruction in 2013 and found that at 10 years follow-up, there was graft rupture rate of 6.2% (0 to 13.4%) and a clinical failure rate of 10.3% (1.9 to 25.6%). The overall cumulative failure rate of ACL reconstruction was 11.9% (3.2 to 27%). Hence 1 in 9 ACL reconstructions fail at 10 years follow-up.

Secondary osteoarthritis

ACL deficiency and partial or total meniscectomy are well known risk factors for post-traumatic OA. Ajuied et al (19) has recently reported the first meta-analysis on the development and progression of OA after an ACL injury at a minimum of 10 years follow-up using Kellgren-Lawrence (K-L) classification of radiographic OA. Their systemic review and meta-analysis showed a 20.3% prevalence of grade 3 and 4 OA in patients with ACL deficiency as compared to 4.9% in the contralateral ACL intact uninjured injured knee.

The study also showed that the relative risk (RR) of developing even minimal (grade 1 and 2) OA was 3.89 and the relative risk of moderate to severe (grade 3 and 4) OA was 3.84 after an ACL injury irrespective of whether the treatment was surgical or conservative. The nonoperatively treated knees had a higher relative risk of developing any grade of OA as compared to those knees which had reconstructive surgery. However the progression of OA to moderate and severe OA after 10 years was significantly higher in the reconstructed knees (RR 4.71). 

Porat et al (20) studied the prevalence of radiologic OA in a group 205 male league soccer players and found that, at 14 years after the initial ACL injury 78% of the injured knees had radiologic evidence of OA. Grade 2 or more K-L radiographic changes were seen in 41% of the injured knees and 4% of the uninjured knees. There was no difference in the prevalence of radiologic OA between knees treated conservatively or with reconstruction. The patient relevant outcome was affected with 80% of the subjects reporting a reduced level of activity after the injury. However the level of activity was the same in patients with and without OA. Fifty-five percent of the subjects reported participation in a level 5-6 activity (high level recreational activity) and 53% reported a level 2-4 activity participation (easy to moderate load at work). In fact 7.8% were still involved in organised soccer 14 years after the ACL injury. The study found no difference in the prevalence of OA or symptoms in subjects treated conservatively or surgically.

Although the meta-analysis by Ajuied et al (19) showed a higher relative risk of OA in patients treated without reconstruction, the study by Porat et al (20) in soccer players showed no difference in the prevalence of radiographic OA in those treated conservatively or with surgery. This could partly be due to the knee protective neuromuscular rehabilitation that soccer players go through before resuming sports as compared to others who are not involved in competitive sports. 

Neuman et al (11) showed in a prospective level 2 study involving 100 consecutive patients, who were treated by neuromuscular rehabilitation and activity modification after an ACL injury, that it is possible to achieve a good knee function with a low prevalence of post-traumatic OA at 15 years follow-up. In this study the attrition rate was low with 6 patients lost during follow-up. A delay ACL reconstruction was necessary in 22 patients (23%) at between 6 months and 11 years. Tibiofemoral OA of K-L grade 2 or more was present in 16% of the patients and all these patients belonged to the group who had menisectomy done. None of the patients with an intact meniscus had OA. The OA occurred in the same compartment as the menisectomy. Thirty-five percent of the patients with ACL reconstruction had tibiofemoral OA whereas 11.2% of the patients without reconstruction had tibiofemoral OA.

As far as symptoms were concerned 67% of the patients were asymptomatic at 15 years. Of these 67%, OA was absent in 59% and present in 8%. Thirty-three percent of the patients were symptomatic, of whom 24% had no OA and 8% had OA. Patients with ACL reconstruction complained of more knee pain than those without reconstruction and patients with major meniscal tear had more knee pain than those with intact menisci. Patients with radiographic tibiofemoral OA scored lower in all subscales of KOOS as compared to those without OA. The authors concluded that in patients willing to moderate their activity level, initial treatment without ACL reconstruction should be considered because favourable outcome in terms of knee function, symptoms and radiographic OA can be obtained in the long term with nonoperative treatment.

The study by Ajuied et al (19) showed a higher risk of OA in patient treated conservatively as compared to those treated surgically while the study by Neuman et al (11) showed that the patients treated by reconstruction of the ligament had a higher prevalence of OA. The study by Porat et al (20) on the other hand showed that there was no difference in the prevalence between the two groups. These differences in different studies may be due to inconsistences in the acquisition and interpretation of radiographs as well as inconsistences in definition of OA and variation of the cohort of patients studied.

There is a wide variation in the incidence of OA reported after ACL injuries and it is difficult to make firm conclusion about the prevalence OA after ACL injuries because no universal methodological radiologic classification method exists. Different studies use different classification methods. Oiestad et al (21) in a systematic review of incidence OA after ACL injury where the patients were followed-up for more than 10 years found that the highest rated studies reported lower rates of OA. In the highest rated studies they found that the incidence of OA with isolated ACL injuries was between 0 to 13% and in patients with combined injuries (ACL/Meniscus) was between 21% to 48%. 

 The level 1 high quality study by Frobell et al (11) has showed that there is no difference in the prevalence of OA in patients treated with rehabilitation, early ACL reconstruction or delayed ACL reconstruction. However in this study they found that the prevalence of patellofemoral OA was higher at 20% as compared to the tibiofemoral OA which was 12%. They also found that the prevalence of patellofemoral OA was higher in patients who had reconstruction with patellar tendon grafts as compared to hamstring tendon grafts. It is believed that shortening of the patella tendon after harvesting of the graft may increase the biomechanical loading of the patellofemoral joint leading to OA, as well as due to osteophyte formation that occurs due bone remodelling after the graft is harvested. The conclusion from this study is that reconstruction of the ACL does not protect the knee from OA.

Risk of arthroplasty after ACL injury

Studies evaluating the risk of knee replacement after ACL injuries is lacking probably because the incidence is very low. Leroux et al (22) did a population-based matched cohort study to evaluate the risk of arthroplasty following ACL reconstruction. They obtained administrative databases of patients who had ACL reconstruction in Ontario, Canada, from 1993 to 2008. They identified 30,301 patients who had ACL reconstruction and 151,362 individuals from the general population with similar demographic variables. They found that 209 patients with ACL reconstruction and 125 patients from the general population had knee arthroplasty. The cumulative incidence of knee arthroplasty following ACL reconstruction after 15 years was low at 1.4% and in the general population it was 0.2%. Age of 50 years or more, female sex, comorbidity, surgeon annual volume of ACL reconstruction of 12 or less per year and reconstruction of the ACL done at university affiliated hospital, increased the odds of knee arthroplasty. Male sex and an age of 20 years or less were protective indicators. Meniscal tears, however, were not associated with increased risk of knee arthroplasty.

The limitations of this level 3 study was that it is not known how many of these patients had OA at the time of ACL reconstruction and neither was information about concomitant PCL injury and revision reconstructions available.

Conclusion

Level I scientific evidence shows that only about 50% of young active individuals will need an ACL reconstruction after an ACL injury. Level II scientific evidence shows that if professional sport individuals and those not willing to reduce their activity level are excluded then only about 25% of individuals will require an ACL reconstruction after an ACL injury.

After ACL reconstruction about 90% of patients will have a successful surgical outcome and about 63% can return to preinjury level sports participation. Only 44% can return to competitive sports. Cumulative failure rates can be as high as 27% though the mean is about 12%.The figures would probably higher when surgery is performed by low annual volume surgeons.

Though it is commonly believed that ACL laxity predisposes the patient to meniscal injury but the study by Frobell did not show any difference in meniscal injury rates in patients treated surgical and in those treated conservatively. 

The incidence OA after ACL injuries is not as high as is commonly believed. High rated studies report a 0 to 13% incidence of OA in patients with isolated ACL injuries and a 21% to 48% incidence in patients with combined ACL and meniscal injuries. There is no evidence that ACL reconstruction reduces the incidence of post-traumatic OA of the knee.

Though there is lack of good evidence on the risk of knee arthroplasty after ACL injuries, one level III study suggests that about 1.4% of patients with ACL reconstruction run a risk of needing an arthroplasty of the knee after 15 years.

References

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11.   Neuman P, Englund M, Kistogiannis J, Friden T, Ross H, Dahlberg LE. Prevalence of tibio-femoral osteoarthritis 15 years after nonoperative treatment of anterior cruciate ligament injury: A prospective cohort study. Am J Sports Med 2008; 36(9):1717-1725

12. Ardern CL, Webster KE, Taylor NF, Feller JA. Return to sport following anterior cruciate ligament reconstruction surgery: a systematic review and meta-analysis of the state of play. Br J Sports Med 2011; 45:596-606.

13. Swirtun LR, Renstrom P. Factors affecting outcome after anterior cruciate ligament injury: a prospective study with a six-year follow-up. Scand J Med Sci Sports 2008: 18: 318–324.

14. Church S, Keating JF. Reconstruction of the anterior cruciate ligament: Timing of surgery and the incidence of meniscal tears and degenerative changes. J Bone Joint Surg (Br) 2005; 87B:1639-42.

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