ACL reconstruction surgery alternatives and regenerative treatment options

Ross A. Hauser, MD, Danielle R. Steilen-Matias, MMS, PA-C.

ACL reconstruction surgery alternatives and regenerative treatment options

Is ACL reconstruction surgical repair the right option for every patient? In this article, we review the latest medical research that can help the patient/athlete understand their ACL pre and post-surgery challenges. If you are reading this article you may be debating whether to have surgery or not or that you are on the waiting list to get surgery. One option for treatment we will explore is regenerative medicine, non-surgical treatment options, and the realistic assessment of whether or not this can help you.

People who get ACL reconstruction surgery can have excellent results. These are not the people we see in our office. We see the people for whom the promise of ACL reconstructive surgery did not offer the same excellent results. We see the people who have had an ACL reconstruction, ACL reconstruction with meniscus repair, and second or revision ACL surgery for a rupture of the “fixed” ACL. We see the people for whom ACL surgery was not the answer and they need help. Now they are exploring options to either get them back to sports or to try to avoid what they were told was the inevitable advancement of osteoarthritis.

We also see the people who have to decide should they have the surgery or not. These are people who debate whether or not the surgery will be worth it for them and the long rehabilitation it implies. These may be people who have an urgency to return to sport before academic eligibility expires or the people who do a physically demanding line of work and have to way surgery versus other options to keep them on the job.

Summary points of this article:

For many people, the hardest part of their injury is the decision as to what to do about it and waiting for a surgery date. Many ask: “Is ACL reconstruction really necessary?” “Can I get by without an ACL?”

For the young athlete who has an aspiration for a college athletic career, seemingly there is no choice but surgery. For the high school sophomore who wants to play their senior year and finish their youth sports career on the field, there seems to be only one choice, surgery. But what about the older recreational athlete, what about the person who works at a physically demanding job? What about the older patient? Is ACL reconstruction really necessary?

Someone who is debating surgery or no surgery will come into our clinics and tell a story that sounds like this:

My MRI confirmed that I have a torn ACL and a meniscus tear. My surgeon wants me to try Physical Therapy first as she suggested people can live without an ACL and do so happily. If my knee felt unstable, not right, or caused me any functional problems and/or I had to alter my lifestyle, then the ACL reconstruction surgery should be performed and the meniscus should be dealt with.

The PT seemed to go very well, I was fitted with a large brace, had a three a week schedule of PT, and felt really good. While I felt my leg getting stronger, I realized that my knee remained unstable. I was fitted for a “better brace.” Now here I am looking for a non-surgical answer to my knee instability if one exists. (A person like this is seeking stability treatment for the whole knee, this means an examination of all the existing ligaments and a plan to strengthen those – see below).


Surgery or no surgery? First, let’s assess an ACL tear

You may have an ACL tear and this tear may be one aspect of a significant knee injury including the PCL. The posterior cruciate ligament (PCL) is one of four ligaments of the knee. The primary purpose of the PCL is to hold the shin bone in its proper alignment to the knee. As the PCL is a strong ligament, it would take a lot of impacts to injure it. Therefore it is usually not injured in isolation, it is usually injured when the knee has taken a significant impact blow and other ligaments are torn such as the more famous ACL, and there is damage to the meniscus.

ACL and PCL injuries frequently involve other knee structures. Ligament ruptures and meniscal tears often occur in combination when forced medial (knee forced inward towards the other) or lateral  rotatory motion (whichever way the knee was moving suddenly the knee went in a different direction – a cutting move for example or the knee suddenly moved in a way while your foot remained fixed or stationary.) To reiterate: Ligament and meniscal tears occur from sudden changes in direction, placing excessive forces on the intra-articular structures of the knee. The menisci and the anterior cruciate ligament are the most frequently injured structures, but the PCL may also tear, with a 10:1 ratio in favor of the ACL over the PCL.

In a substance tear (where the ACL is still attached to the thigh and shin bones and the tear is through the ligament itself) of the ACL, the blood supply is usually permanently disrupted, resulting in poor healing potential. Injury to the ACL of the knee has a poor prognosis for healing, a predisposition for a recurrent knee injury, concurrent intra-articular meniscal and hyaline cartilage damage, progressive joint instability, and a propensity toward the development of osteoarthritis. Unlike the ACL, because of the association, the PCL has with the posterior capsule, its blood supply is not permanently lost when a substance tear occurs, resulting in a more favorable prospect for healing from injuries to the PCL.

As you may have been told by your doctors: Ligament reconstruction is the usual management technique for significant ACL and PCL injuries, using replacement auto- or allografts, however, have less than satisfactory outcomes, including instability that could progressively damage other knee structures.

Does the MRI correctly see the ligament damage? Does it see “too much?”

What does it mean when we suggest the MRI is seeing too much? It means that the MRI took a picture and the radiologist’s interpretation suggests a full-blown tear when a full-blown tear may not be there.

In January 2022, doctors writing in the journal BioMed Central Musculoskeletal Disorders (32) assessed the accuracy of MRI in diagnosing and classifying acute traumatic multiple ligament knee injuries. Here is what they wrote:

“Magnetic resonance imaging (MRI) is widely used for the evaluation of knee injuries, however, the accuracy of MRI in classifying multiple ligament knee injuries remains unknown.” (In other words the study’s authors are saying, we do not know how accurate this is).

Therefore, their study’s goals aimed to investigate the accuracy of MRI in diagnosing and classifying acute traumatic multiple ligament knee injuries. The study authors noted that they are going into this study believing that the MRI had high accuracy in detecting and classifying multiple ligament knee injuries. Let’s see if those beliefs are founded.

The doctors looked at 97 patients who were diagnosed with acute traumatic multiple ligament knee injuries and managed by multi-ligament reconstruction. The MR images were read by two experienced radiologists and results were compared with intraoperative findings, which were considered as the reference for the identification of injured structures.

Results: For detecting the specific injured structures in multiple ligament knee injuries, MRI had high sensitivity (90.7% for ACL, 90.4% for PCL, and moderate specificity (63.6% for ACL, 50% for PCL).

What does this mean?

Sensitivity for MR imaging to identify something that MAY be a tear was at 90%. Meaning that the MRI interpretation was correct in seeing a tear 90% of the time. The significance of the tear, full or partial, then because less odds-worthy. Moderate specificity for the ACL tear means that when these 90% of people were separated into probable and non-probable (specific to the type of tear, hence the word specificity) 63.6% of the time the tear was correctly identified. About two out of three times.

Some people do not need ACL reconstruction surgery to return to play. “Whether surgical or conservative treatment is more effective in allowing patients to return to physical activity after anterior cruciate ligament (ACL) injury is controversial.”

A paper published in December 2017 (1) weighed in on the ACL Surgery or Not Debate.

The doctors of this study noted: “Whether surgical or conservative treatment is more effective in allowing patients to return to physical activity after anterior cruciate ligament (ACL) injury is controversial. We sought to compare mid-term outcome measures between isolated ACL tear patients who underwent reconstruction followed by closed kinetic chain exercises and those who underwent neuromuscular training only.”

Okay so in this study, what was the outcome? No statistical difference was observed.

“No statistical difference was observed between the groups for any of the parameters evaluated, including assessment of subjective knee function, one-leg hop test, assessment of joint position sense, muscle strength, and the health profile.”

The conclusion?

“Our data suggest that early surgical reconstruction may not be a prerequisite to returning to recreational physical activities after injury in patients with ACL tears.”

For some people, you do not need ACL reconstruction surgery to return to play. We do realize that this is a hot-button suggestion and that many people will point to professional athletes as proof of the need for an ACL reconstruction surgery. Please keep reading, there is so much more to discuss.

Complete or a partial ACL tear, is ACL surgery is necessary? Some patients exhibit little or no symptoms when they play low-demanding sports or activities.

Generally, with a documented complete rupture, the patient has a choice of reconstruction surgery or non-surgical options. The non-surgical options would include first: A realistic assessment of future activities on an ACL-deficient knee. Some patients exhibit little or no symptoms when they play low-demanding sports or activities.

Here are the arguments for operating on a partial ACL tear:

Research from a combined team at Rush University Medical Center, Columbia University Medical Center, and the Hospital for Special Surgery:

This is what doctors at Oxford University asked: They suggest that patients should always take caution when any type of joint surgery is recommended, and reconstruction of the anterior cruciate ligament (ACL) is no different. It is widely known that many patients who undergo ACL reconstruction experience a chronic “giving way” feeling after the surgery and some encounter a re-rupture of the tendon. (19)

When do conservatively treated partial ACL tears progress to full-blown ruptures?

A 2019 study in the Orthopaedic Journal of Sports Medicine (20) assessed the incidence and risk factors for the progression of partial ACL tears to complete ruptures after nonoperative treatment in active patients younger than 30 years old. Here are the observations and learning points of this study:

The initial finding is that about four out 10 ten younger patients with a partial ACL tear would eventually see that tear progress to a full rupture on average about 3.5 years after the partial tear diagnosis.

Patients under 20 who participated in pivoting contact sports (soccer, basketball) were at higher risk and when they ruptured their ACL, meniscus damage was discovered that occurred previous to the rupture injury or was part of the rupture impact.

Returning to the research:

“Despite common misconceptions to the contrary, research suggests that it is possible for an individual who suffers an ACL rupture to return to sport following management with rehabilitation alone”

Here is a 2019 study from the University of Oxford, Oxford, and the Norwegian School of Sport Sciences. (10) the question being asked is “Do the outcomes of ACL rupture differ depending on management strategy?” Here are the learning points of this research:

Here the researchers go further in the surgery or no-surgery debate.

“Despite common misconceptions to the contrary, research suggests that it is possible for an individual who suffers an ACL rupture to return to sport following management with rehabilitation alone. Several studies have found no difference in physical activity levels or return to sport rates between patients managed with ACL reconstruction surgery and those managed with rehabilitation.”

A functional knee – does ACL reconstruction restore it?

Building on the 2017 study above is an August 2021 paper that looked at knee function after ACL reconstruction. (31) The keywords here are “proprioceptive deficits.” In short proprioceptive deficits are troubles standing on one foot, knee giving way, balance issues, falling over, clumsiness, a sense of loss of coordination.

The researchers here wrote: “Anterior cruciate ligament (ACL) injuries cause mechanoreceptor loss in the joint; (Explanatory note: mechanoreceptors sense things around them such as “the ground is hard,” “the ground is soft” and helps the knee and brain make adjustments). Therefore, proprioceptive deficits are observed after injury. (The knee sensors are not sure if the ground is hard or soft if the ground is at an incline or not, you become clumsy).

The researchers then set out to evaluate proprioception (sense of position) in patients who had undergone ACL reconstruction in functional positions used in daily life according to joint angles where ACL injuries occur more frequently, in comparison with healthy controls.

The researchers used “closed kinetic chain position.” Mainly your feet are fixed in position on the floor. So in this exercise, patients were asked to squat to the thirty-degree angle. What the researchers found was the ACL reconstructed knee was confused and it was confusing the patient’s “healthy” non-operated other knees. How?

Conclusion:  (This research showed) that proprioceptive sense was still poor in patients with ACLR compared with the control group, even if an average of 24 months have elapsed since surgery. 

Early Return to Play Not Recommended for Student-Athletes – More damage to meniscus and cartilage

A November 2021 study in the Progress in Rehabilitation Medicine (2) investigated whether student-athletes with anterior cruciate ligament (ACL) injuries who returned to sports without reconstruction could continue their sporting activities until the end of the season and whether there was an increase in secondary damage associated with knee instability.

How was the study done?



Is ACL reconstruction surgery a guarantee to return to play? Hardly. Research: “some athletes still fail to return to play”

Again, we point out that some people do great with ACL reconstruction surgery. These are, however, not the people we see in our offices.

Research from Brown University (3) presents the return to play reality:

ACL reconstruction does provide remarkable short-term knee stability.  Unfortunately, the stability doesn’t last because no matter how hard the surgeons try, they can not simulate exactly the same biology pre-injury. If a patient has a grade 3 ligament tear, and the patient deems the ACL necessary, surgery is indicated. The cadaver or tendon graft that is replacing the torn ligament, however, will not function long-term like the original ACL.

Research: Doctors and patients should abandon “time frames” as a reason to get surgery.

A patient or a patient’s parents may make the decision to proceed with ACL reconstruction surgery because “the season starts in March or the season starts in September.” Therefore the decision to surgery is based on a pre-determined time when the surgery must be completed and the rehabilitation and recovery are completed.

A June 2020 paper in the Orthopaedic Journal of Sports Medicine (11) dispels this type of thinking. This study investigation was performed at the University of Pittsburgh Medical Center. Here are the summary learning points

“A precise and consistent definition of return to sport after anterior cruciate ligament (ACL) injury is lacking, and there is controversy surrounding the process of returning patients to sport and their previous activity level.”

(the) Key points include that return to sport is characterized by the achievement of the preinjury level of sport and involves a criteria-based progression from a return to participation to return to sport and, ultimately, return to performance.”

What the doctors are looking for is a consensus as to what constitutes a return to sport “success.”

“Purely time-based return to sport decision-making should be abandoned.”

“Purely time-based return to sport decision-making should be abandoned.”

What the doctors are saying is that “The season starts in March, the season starts in September” as a means for surgery and subsequent treatment should be abandoned as a means to guide the patient’s decision-making process to have surgery or not.

“Progression occurs along with a return to sport continuum, with decision-making by a multidisciplinary group that incorporates objective physical examination data and validated and peer-reviewed return to sport tests, which should involve functional assessment as well as psychological readiness. Consideration should be given to biological healing, contextual factors, and concomitant injuries.”

Simply, you cannot put a time frame on recovery, ACL repair is a long journey with many peaks and valleys.

This situation does describe someone we would see in our office, the patient who had successful ACL reconstruction but their knee is “still not right.” Why does the knee not feel right?

Instability due to an ACL injury or as a product of surgery will precipitate the eventual breakdown of proper knee function, rotatory instability, meniscal tears, degenerated cartilage, and osteoarthritis. The disruption that occurs from changes in the normal motion and mechanics of the knee joint due to joint instability furthermore leads to, or is associated with, the development of a host of secondary pathophysiologic conditions of the knee. Injury to one knee structure frequently affects other elements of the knee, causing ligament ruptures and meniscal tears, which often occur in combination.

Above we touched on the sense that the knee was having “proprioceptive deficits” that is balance and coordination issues. In this study from the Hospital of Special Surgery published in Current Reviews in Musculoskeletal Medicine, September 2017 (4) we will get a further sense of when the knee is not right even after successful ACL repair.

These deficits may not only negatively impact sports performance but also raise the risk of re-injury.

People are in our office because they also want to explore non-surgical regenerative medicine. Here we may be able to address knee instability by examining and strengthening the weakened and damaged ligaments in the operated knee, and now, the knee weakened by compensating for the other side injury.

The return to play protocol is controversial

The above 2017 study was cited in a 2020 paper in the Orthopaedic journal of sports medicine (33) which followed along with the guidelines that “a precise and consistent definition of return to sport after anterior cruciate ligament (ACL) injury is lacking, and there is controversy surrounding the process of returning patients to sport and their previous activity level.”

The long-term results from many studies demonstrate that untreated joint instability remains.

Doctors from the Hospital for Special Surgery and Cornell Medical Center Program in New York reported in the Orthopaedic Journal of Sports Medicine (5) of the over 23,000 pediatric patients who underwent ACL reconstruction:

The median time lapse between the first and second surgeries was 1.4 and 1.6 years, respectively.

Failure of primary ACL reconstruction can be attributed to:

This is pointed out by Italian researchers who in part blame the ACL failure on compromised ligaments and the meniscus of one or both knees. Published in the Sports Medicine and Arthroscopy Review, (6) here are the highlights of this research:

Now let’s look again at knee instability and the failed ACL graft

In December 2021 in the journal Arthroscopy (8) orthopedic surgeons created a comprehensive list of degenerative knee issues that could cause increased ACL forces and pathologic knee kinematics (wobbly, loose, unstable knee) to evaluate what could cause an ACL graft overload in primary and revision ACL reconstruction. What they found was a whole knee problem.

In examining 43 previously published cadaver studies, the authors found that the studies reported that high volume medial and lateral meniscectomies, peripheral meniscus tears, medial meniscus ramp tears, lateral meniscus root tears, posterolateral corner injuries, medial collateral ligament tears, increased tibial slope, and valgus and varus alignment were reported to have a significant impact on ACL (graft) force and related knee kinematics.

Lateral Posterior Tibial Slope

Lateral Posterior (backside) Tibial Slope (Angle of the top of the tibial or larger shin bone). The greater the angle or slant of the slope, the more likely anterior cruciate ligament reconstruction can fail.

Doctors have noted this. A December 2020 study from the University Hospital of Udine in Italy (9) recognized the role of the lateral posterior tibial slope as a potential risk factor for ACL reconstruction failure.

In this study, 47 patients who underwent second or revision ACL surgery were examined, in particular for Lateral Posterior Tibial Slope angles. What was found was that patients getting a second ACL reconstruction or revision surgery had significantly higher than the normal angles.  Furthermore, females show a Lateral Posterior Tibial Slope significantly higher than males.

Conclusion: Doctors should examine the posterior lateral tibial slope as this higher slope can be a factor in a higher risk of ACL reconstruction failure.

One in four patients will have THREE ACL surgeries on the same knee within 2 – 9 years

Continuing with this study, the researchers found: “Subsequent knee injury is common following ACL reconstruction; one-third of young individuals who undergo ACL reconstruction experience a second ACL tear and 27% experienced a third within 2–9 years after revision ACL reconstruction.”

Studies do not support that early ACL reconstruction prevents additional meniscus and cartilage injury

A common belief is that early ACLR prevents additional meniscus and cartilage injury. However, studies referenced to support this belief are typically retrospective reviews of surgical records, and show more severe joint injury in patients presenting for ACL reconstruction months or years after ACL rupture. . . On the other hand, evidence from prospective studies does not suggest management with rehabilitation as the first-line treatment results in more joint injury compared with management with early ACL reconstruction. . . In summary, the best available evidence does not indicate that an individual is at greater risk of subsequent injury if they are managed with rehabilitation as the first-line treatment as opposed to ACL reconstruction.

A father tells the story of his daughter, a High School age softball player who had attracted college attention.
She tore her ACL

While this is a typical case history, the results may not be typical for everyone.

Where is the role of knee instability in ACL repair? April 2018, 20 years follow-up. Patients who had ACL reconstructive surgery were more likely to have knee osteoarthritis than those who did not.

Doctors at Erasmus University Medical Center, Rotterdam, the Netherlands looked at fifty patients who had an ACL rupture from the 1990s. (12) Twenty-five patients were treated nonoperatively in 1992, consisting of structured rehabilitation and lifestyle adjustments. Twenty-five were surgically treated between 1994 and 1996 with ACL reconstruction featuring a patella tendon.

What this research suggests is that ACL reconstruction therapy may not provide the overall knee stability needed to prevent degenerative knee disease.

Knee instability and multiple ACL surgeries

It makes no sense that a person is subjected to multiple surgeries when it is obvious that joint instability is the cause of the problem. Joint instability is the missing diagnosis for athletes with ACL tears, and additional surgeries, no matter how sophisticated, are not the answer to the problem of joint instability. Pain, swelling, weakness, popping, grinding, and other symptoms associated with ACL tears can be addressed not with surgery, but with Prolotherapy.

We see many patients following ACL reconstruction surgery for Prolotherapy. They come in once their knee feels unstable and weak. As extensive independent research points out, the long-term results of initial ACL reconstruction demonstrate that untreated joint instability remains. After an examination, we recommend patients consider comprehensive Prolotherapy to treat the whole knee complex to help prevent the need for secondary surgery and to accelerate ACL reconstruction surgery recovery time. We discuss these points further below.

What are the excellent results in ACL reconstruction surgery? That is hard to say. The problem is that orthopedic surgeons’ perspectives of excellent results are different than athletes’ perspectives.

How soft tissue heals. Following an ACL trauma, the knee ligaments, even if pronounced "uninjured," can still be sprained, stretched,  and loose. If these ligaments are not treated or strengthened, chronic knee instability and a continuous, abnormal, destructive knee motion ensues. This is the origins of knee traumatic osteoarthritis. This destructive joint motion and the degeneative process it causes can be treatment, in many cases, healed, with Prolotherapy and Platelet Rich Plasma injections. 

Following an ACL trauma, the knee ligaments, even if pronounced “uninjured,” can still be sprained, stretched,  and loose. If these ligaments are not treated or strengthened, chronic knee instability and a continuous, abnormal, destructive knee motion ensue. This is the origin of knee traumatic osteoarthritis. This destructive joint motion and the degenerative process it causes can be treated, in many cases, healed, with Prolotherapy and Platelet Rich Plasma injections. 

Patients’ expectations of excellent results in ACL reconstruction surgery not met

What are excellent results in ACL reconstruction surgery? That is hard to say. The problem is that orthopedic surgeons’ perspectives of excellent results are different than athletes’ perspectives.

As mentioned above, one of the main reasons for having the ACL surgery was the ability to return to sports. For many, this was not achieved.

Doctors from the Karolinska Institutet in Sweden found that patients saw no real choice between operative and non-operative treatment. Athletes perceived surgery as the only way to fully return to the pre-injury level of sports, and surgery was understood as the only way to become a completely restored “functional human being”.(13)

A major source of frustration to the patients was that the progress during the ACL rehabilitation process did not match their expectations, fear of re-injury became common.

Some participants because the expectation of surgical success was not met decided not to return to their sports.

Revision ACL Reconstruction will likely fail AGAIN because of knee instability

In July 2020, a team of researchers from Germany’s leading sports medicine hospitals and universities published a study in the journal Knee Surgery, Sports Traumatology, Arthroscopy (14) to “carefully analyze the reasons for revision ACL revision failure to optimize the surgical revision technique and minimize the risk of recurrent re-rupture.”

The results of their research:

So there is a question as to whether or not ACL reconstruction surgery is the best option. Here is a study on high school and college football players.

Football Hall of Famer Joe Namath is believed to have played his entire NFL career without an ACL. However the damage to his knees were legendary and resulted in knee replacements. The brace on his right knee is clearly visible.

Football Hall of Famer Joe Namath is believed to have played his entire NFL career without an ACL. However, the damage to his knees was legendary and resulted in knee replacements. The brace on his right knee is clearly visible.

Football Hall of Famer John Elway played his entire career without an ACL in his left knee. (The one that is very bent above.) Like Namath, Elway suffered his injury at a time when ACL injuries were career-ending.

Football Hall of Famer John Elway played his entire career without an ACL in his left knee. (The one that is very bent above.) Like Namath, Elway suffered his injury at a time when ACL injuries were career-ending.

This question, whether or not ACL reconstruction is the best option, was further raised by researchers at Vanderbilt University Medical Center. Doctors there noted the lack of data regarding the effect of anterior cruciate ligament reconstruction on the ability of American high school and collegiate football players to return to play at the same level of competition as before their injury or to progress to play at the next level of competition.

Although two-thirds of players reported some “other interest” contributing to their decision not to return, at both levels of competition, fear of reinjury or further damage was cited by approximately 50% of the players who did not return to play.”(15Results that mimic those cited above.

Recently researchers in the United Kingdom put together a paper on best practices of when and type of ACL surgery to consider.

Here is a summary: (16) The aim of ACL surgery is to restore functional stability to the ACL deficient knee. ACL reconstruction can be performed using a variety of different surgical techniques as well as different graft materials.

Timing of any ACL reconstruction is also crucial, it is commonplace to allow the acutely injured knee to settle, giving time for resolution of swelling, restoration of range of motion, and recovery from concomitant ligament injuries. (I discussed this above in regard to meniscus injury).

Furthermore, a delayed reconstruction allows patients to try conservative therapy to see if surgery is indicated. (This is discussed at length below)

The three categories of commonly used grafts are:

The surgical technique used during ACL reconstruction varies widely. Different techniques include arthroscopic vs open surgery, intra vs extra-articular reconstruction, femoral tunnel placement, number of graft strands, single vs double bundle, and fixation method.

July 2021: What are the surgeon’s preferences?

A July 2021 survey of surgeons (17) looked to find the current global trends in anterior cruciate ligament reconstruction amongst surgeons. The paper was co-authored by doctors at the Departments of Orthopaedic Surgery at Stanford University, University Hospitals of Cleveland, The Ohio State University, the University of Pittsburgh Medical Center, and The Cleveland Clinic Foundation among others.

In this next section, we will discuss conservative, non-surgical treatments not discussed in routine studies of ACL conservative care treatment. We will also revisit the partial vs. full rupture ACL tear and its accurate diagnosis and assessment.

Five years later – reconstructive surgery and physical therapy offer the same chances of developing posttraumatic osteoarthritis

In this August 2021 study published in the Orthopaedic Journal of Sports Medicine (30) researchers wrote: “Patients and clinicians often struggle to choose the optimal management strategy for posttraumatic knee osteoarthritis after an anterior cruciate ligament (ACL) injury. An evaluation of radiographic outcomes after a decision-making and treatment algorithm applicable in clinical practice can help to inform future recommendations and treatment choices.” In other words, dividing patients up into the treatments they received after the ACL rupture and then assessing their MRI five years later can help guide patients into deciding to get surgery or pursue conservative care treatments.

In a group of patients, five years after ACL rupture, doctors identified that:

Conclusion: There were no statistically significant differences in any 5-year radiographic outcomes or knee pain among the 3 management groups. Very few of the patients who participated in our decision-making and treatment algorithm had knee osteoarthritis or knee pain at 5 years.

Biomaterials Prolotherapy, PRP and stem cells in partial ACL tears

When discussing non-surgical applications of regenerative medicine such as stem cell therapy, Platelet-rich Plasma therapy, or Prolotherapy, discussions must be tempered with the realistic indications and outcomes that may be expected from these treatments.

What is Prolotherapy and where is the research? Please visit our Prolotherapy research page for extensive and detailed information.

Prolotherapy is a “new” old treatment that has been utilized in clinical practices for over 80 years. Standardized and reviewed in clinical application by Dr. George Hackett in the 1950s, Prolotherapy has been shown to be an effective treatment in patients who suffer from joint instability due to ligament damage and overuse and related musculoskeletal and osteoarthritis. Prolotherapy’s popularity as a treatment for chronic pain has intensified over the past two decades among both physicians and patients as clinical and anecdotal observations have proved in many cases its reliance as a non-surgical option for joint and back pain.

Irritant solutions most often contain dextrose (d-glucose), a natural form of glucose normally found in the body.

In January 2017, doctors writing in the Orthopedic Journal of Sports Medicine wrote of the controversies surrounding the repair of partial ACL tears. One of the controversies was reconstructive surgery. In this study, the researchers found that biologically augmented ACL-repair techniques (PRP and stem cells) improve healing and outcomes of both the native ACL (non-surgery) and the reconstructed graft tissue (surgery). (21)

In 2003, K. Dean Reeves, MD published in the journal Alternative Therapies in Health and Medicine (22) these findings:

PRP injections or ACL Surgery in older patients? As we have seen being ACL deficient can reduce knee stability.

An August 2022 study in the European journal of translational myology (34) a publication dedicated to the study of joints and muscles, writes: “In old patients with ACL rupture, surgery is not recommended due to the person’s low level of activity and knee osteoarthritis. Platelet-rich plasma (PRP) is a good treatment option in inflammatory cases in orthopedics. Hence, the aim of this study was to assess and comparison of the effect of PRP and arthroscopic surgery on anterior cruciate ligament rupture.

How we examine for knee instability under ultrasound. Here we discuss the meniscus which is commonly injured in ACL tears.

The realities of non-surgical ACL regeneration
Stem Cell Therapy and Prolotherapy  – Non-surgical ACL reconstruction?

Stem Cell Therapy involves direct bone marrow aspiration (or also concentrated) to get the stem cells to the site of the injury. We use bone marrow stem cells in conjunction with other Prolotherapy solutions to treat large articular defects in the meniscus areas. Typically, patients are seen every two months. Most patients need 3-6 visits. The good news is during the time of healing, the patient can exercise and start getting back into great shape.

Doctors at the Department of Trauma Surgery and Sports Injuries, University Hospital of Salzburg wrote in the Archives of Orthopaedic and Trauma Surgery:

“The ACL has the potential to heal upon intensive non-surgical rehabilitation procedures. Several biological factors influence this healing process as local intraligamentous cytokines (messengers that call for more inflammation (healing)) and mainly cell repair mechanisms controlled by stem cells or progenitor (creator) cells. Understanding the mechanisms of this regeneration process and the cells involved may pave the way for novel, less invasive and biology-based strategies for ACL repair.”(23)

In 2015, doctors in China excitedly published research in the Chinese Journal of Reparative and Reconstructive Surgery which said: “Enormous progress has been made in tissue-engineered ligament for repair and regeneration of ACL. With the development of biochemistry and scaffold materials, the tissue-engineered ligament will be used in clinics in the near future.”(24)

This research suggests that one day doctors will be able to grow a new ACL in the laboratory and implant it into a knee. That is fantastic news for the people of the future but what about today? Is there a way today to non-surgically repair a damaged ACL? Do you even need to replace the ACL?

Another team of Chinese researchers writing in the medical journal International Orthopaedics noted that the ACL has certain self-healing abilities after acute injury. These self-healing abilities have to do with stem cells (for a detailed discussion on how stem cells work please see my article on stem cell therapy). The Chinese team suggested that leaving behind part of the ruptured ACL remnant would release native stem cells into the new graft and augment healing. In addition, taking stem cells from the remnant ACL may be a potential source of seeding cells for ligament regeneration. (25)

This research found agreement in the work of Korean doctors who wrote in the medical journal Current Stem Cell Research and Therapy of recent developments in mesenchymal stem cell (MSC)-based approaches for enhancing healing after ACL injuries. They suggest that stem cells are a promising treatment option for enhancing biologic healing of ACL grafts and restoring the functional properties to the levels of the native ACL, and ultimately improving clinical outcomes. (26)

What this research suggests is stem cell augmentation for the ACL graft to prevent ACL complications.

The complexity of an ACL tear – Is it full? Partial? Can it regenerate on its own in the proper circumstance?

In 2009, Prolotherapy doctors led by Walter Grote MD published a case history of an 18-year old female patient who returned to sports after a high-grade partial (possibly complete) ACL rupture.

This case report, published in the medical journal International Musculoskeletal Medicine, documented the successful non-surgical repair of an MRI-confirmed high grade or total ACL tear in an 18-year-old female with knee laxity and instability using Prolotherapy and at-home exercise. After treatment, the patient regained full knee function, resumed normal activity, and returned to recreational sport. Post-treatment MRI revealed a healing chronic ACL tear. These findings are notable given that surgical ACL reconstruction is the conventional treatment for ACL tears with such clinical presentation.

As exciting as this sounds, Dr. Grote and colleagues noted that there were too many factors in this ACL healing to confirm it was caused by Prolotherapy treatment alone. Listen carefully to what this case history presented:

Was the MRI of a complete ACL rupture even accurate?

The conclusion: The limitations above prevent a categorical conclusion that Prolotherapy alone contributed to or restored pain-free function and improved the appearance of the MRI. However, the facts of this case and the context provided by prior clinical trials suggest that Prolotherapy at least augmented the healing of a high grade or total ACL tear. These findings further suggest that Prolotherapy may be an alternative treatment to surgery for carefully selected patients and should be assessed as a treatment of ligamentous tears, especially in patients who are unwilling or unable to undergo surgical intervention.” (27)

So what to do with an ACL tear?

We believe the best treatment for a grade 1 or grade 2 tear is Prolotherapy. If someone has a complete ACL tear they should get a consultation with a doctor who specializes in regenerative medicine to decide if surgery or a non-surgical option is the way to go. If surgery is the route to take, based on the patient’s desire to return to high-level competitive sport, then after surgery, Comprehensive Prolotherapy to help provide strengthened stability to the whole knee.

The ACL and degenerative meniscus disease

Patients who have ACL reconstructive surgery and those who forgo ACL reconstructive surgery are both at high risk for osteoarthritis of the knee. This was demonstrated in the research above and in new research from a team of Chinese researchers who published in the April 2018 edition of the American Journal of Sports Medicine found that the deterioration of meniscus was more extensive than that of articular cartilage and subchondral bone in animal studies. Partly due to chronic inflammation and osteoarthritic changes to the extracellular matrix (the healing soup of cells). The fascinating subject of how Extracellular Matrix repairs cartilage is explained in our article. The researchers of this study noted that rupture of the ACL induced changes that not only could explain the contribution of the meniscus to the progress of osteoarthritis but also could provide a cue for initiation of preventive treatments in the early stages of osteoarthritis. (28)

The ACL and PCL (posterior cruciate ligament). The problems of identifying the source of ligament laxity and knee instability

The anterior cruciate ligament sits in front of the PCL and together the ACL and PCL  keep the tibia (shin bone) from sliding too far forward and the tibia in the position below the femur (thigh bone). The PCL is the knee’s basic stabilizer and is almost twice as strong as the ACL.

This illustration describes the interaction between the various knee ligaments and how together they provide stability or instability to the knee.

This illustration describes the interaction between the various knee ligaments and how together they provide stability or instability to the knee.

A 2018 study in the Journal of Surgery discusses the problems of identifying the true nature of knee instability causes and this research surrounds the PCL (29).

The researchers noted that “ACL tear in concomitant chronic ACL and posterior cruciate ligament (PCL) deficient knees may produce knee laxity, which is more difficult to assess on clinical examination, which in turn may affect the management algorithm of the patient.”

In our article Posterior Cruciate Ligament Injury and Treatments, we identify this problem and discuss the treatment of PCL damage. Briefly, we suggest: “Posterior cruciate ligament (PCL) injuries make up between 3 and 20 percent of all knee ligament injuries. However, PCL injuries are often left diagnosed. Why it is left undiagnosed and untreated is because the PCL is not well understood.”

Understanding and strengthening the PCL is an important factor in ACL injured knees.

All the ligaments of the knee work to stabilize an ACL injury and ACL deficient knee

The ACL’s job is to prevent the tibia and the femur from moving excessively on each other. When it is injured or not there, it puts stress on the other ligaments to prevent this excessive motion.

If you are debating ACL reconstruction because of long rehabilitation, unsureness that the surgery will be successful, already had one ACL reconstruction. Please consider a consultation. What we will discuss with you is:

Summary and contact us. Can we help you?

We hope you found this article informative and it helped answer many of the questions you may have surrounding your knee problems.  If you would like to get more information specific to your challenges please email us: Get help and information from our Caring Medical staff


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This article was updated February 16, 2022




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