Until recently, a complete anterior cruciate ligament rupture on MRI usually led to a familiar conversation about ACL surgery. The ligament was thought to have little meaningful capacity to heal, particularly when the torn ends were separated or the patient was older. For active patients, ACL reconstruction became the accepted way to restore mechanical stability.
That position is now being reconsidered.
ACL reconstruction remains an important and effective treatment. It is often the most appropriate option for young athletes returning to pivoting sport, patients with persistent instability, and injuries accompanied by significant meniscal or cartilage damage. What has changed is the assumption that a complete ACL rupture can never regain continuity.
MRI studies have now documented ACL healing after rehabilitation alone, structured bracing and selected platelet-rich plasma protocols.[1–6] These findings do not establish that every torn ACL can heal without surgery. They do, however, make non-surgical ACL repair a legitimate clinical and research question.
Our most recent publication adds another important observation. Serial MRI documented progressive re-continuity of a complete ACL rupture in a 65-year-old man after treatment began approximately six weeks after injury. The patient did not use a brace. Following five image-guided PRP treatments, MRI demonstrated improved fibre organisation and apparent re-continuity at 14 weeks, followed by further maturation of a continuous ACL-like structure at 50 weeks.[6]
A single case report cannot prove that PRP caused the ligament to repair. Spontaneous healing cannot be excluded, and MRI continuity does not automatically establish normal strength or stability. The significance of the case is more measured: it shows that an older patient with delayed treatment may still demonstrate structural ACL re-continuity under biologically supported conservative care.
That possibility deserves careful investigation.
Can an ACL Heal Without Surgery?
Yes. In some patients, MRI evidence proves that it can.
The strongest evidence that ACL healing is biologically possible did not initially come from PRP treatment. It came from patients managed with rehabilitation.
A secondary analysis of the KANON trial found MRI evidence of ACL healing at two years in 30% of participants initially allocated to rehabilitation with optional delayed reconstruction. Among those who remained in the rehabilitation-only pathway, 53% demonstrated MRI evidence of healing.[1]
Patients whose ACL appeared healed on MRI also reported more favourable sport, recreation and quality-of-life outcomes than participants whose ligament remained non-healed or who underwent early or delayed reconstruction.[1]
These results do not mean that rehabilitation reliably repairs every ACL. They show that the traditional statement that a ruptured ACL cannot heal is too absolute.
Once healing is accepted as biologically possible, several practical questions follow:
- Which tear patterns have the best chance of regaining continuity?
- Does the distance between the torn ends matter?
- How important are age and timing?
- Can early protection improve the healing environment?
- Can PRP support ligament repair?
- How should healing be monitored?
- Does continuity on MRI translate into durable mechanical stability?
These questions are now more useful than treating every complete ACL rupture as biologically identical.
Why ACL Reconstruction Became the Standard Treatment
ACL reconstruction became standard treatment for good reasons. The ACL is an important stabiliser of the knee, particularly during rotation, sudden deceleration and changes of direction. A functionally unstable ACL-deficient knee may give way repeatedly, increasing the risk of meniscal injury, cartilage damage and loss of confidence during sport. ACL reconstruction provides a reproducible way to restore stability by replacing the damaged ligament with a graft. Depending on the surgical technique, this may involve tissue taken from the patient’s hamstring, quadriceps tendon or patellar tendon, or occasionally donor tissue.
For many patients, this remains an appropriate treatment.
The emerging evidence for non-surgical ACL healing should not be used to dismiss the value of ACL surgery. It should be used to improve patient selection and sequencing. The relevant question is not whether ACL reconstruction works. It clearly can. The question is whether every patient should commit immediately to graft reconstruction before the healing potential of the native ligament has been assessed.
ACL Surgery Is Effective, but It Is Not a Neutral Intervention
ACL reconstruction involves an operation, graft selection, bone tunnels and a substantial period of rehabilitation.
Where an autograft is used, tissue must be harvested from another part of the patient’s knee or leg. The consequences differ according to graft choice.
A network meta-analysis of randomised trials found lower donor-site morbidity with hamstring and quadriceps tendon grafts than with bone–patellar tendon–bone grafts.[9] A separate systematic review of Level I studies found that after bone–patellar tendon–bone ACL reconstruction, reported anterior knee pain ranged from 5.4% to 48.4%, while kneeling pain ranged from 4.0% to 75.6%.[10]
These ranges are broad because surgical methods, patient groups and outcome definitions vary. They nevertheless illustrate that graft harvest is not biologically free.
ACL reconstruction also does not remove the possibility of another ACL injury. A systematic review of younger athletes found an overall second ACL injury rate of 15% after reconstruction. This increased to 21% in patients younger than 25 and 23% in younger athletes who returned to sport.[11]
Those figures should not be interpreted as an argument against ACL surgery. Younger athletes participating in high-risk sports are already a particularly vulnerable group. The figures do show why preserving the native ligament, when it is genuinely possible and functionally successful, may have value.
ACL Healing on MRI: What the Cross Bracing Research Showed
The Cross Bracing Protocol provided some of the most striking early imaging evidence that a completely ruptured ACL could regain continuity.
In the original cohort, 80 patients who presented within four weeks of ACL rupture had the knee immobilised at 90 degrees of flexion for four weeks. Range of motion was then progressively increased, with brace removal at 12 weeks and supervised rehabilitation continuing throughout the protocol.[2]
At three months, 90% of participants demonstrated some evidence of ACL continuity on MRI. Patients with the most favourable MRI healing grade also had better knee laxity measurements, patient-reported outcomes and return-to-sport results. Eleven patients, or 14% of the cohort, sustained another ACL injury.[2]
The study changed the discussion around ACL biology. It supported the principle that bringing the torn ligament ends into a favourable mechanical position may allow repair to occur.
However, the protocol is demanding. Four weeks fixed at 90 degrees is uncomfortable and may contribute to muscle loss, stiffness and a substantial interruption to normal life.
More importantly, MRI continuity does not guarantee durable stability in every patient group.
A 2026 controlled cohort study compared the Cross Bracing Protocol with surgical stabilisation in patients aged 16 to 40 who intended to return to pivoting sport. At two years, recurrent instability occurred in 70% of the cross-bracing group compared with 2.5% of the surgical group. Medial meniscal tears were also substantially more frequent in the cross-bracing group.[3]
That study examined a specific high-risk population and a specific bracing protocol. Its findings should not be applied indiscriminately to every older patient, low-demand patient or biologically supported non-surgical pathway.
It does provide an important warning: healing on MRI cannot be treated as the only outcome that matters. The ligament must also provide functional stability.
PRP for ACL Tears: What Does the Evidence Show?
Platelet-rich plasma is prepared from the patient’s own blood. Centrifugation is used to concentrate platelets and selected cellular components into a smaller volume of plasma.
Platelets are not simply involved in clotting. When activated, they release growth factors, cytokines and signalling proteins involved in angiogenesis, cell migration, collagen production, inflammation and extracellular matrix remodelling.[19,20]
These mechanisms create a biological rationale for using PRP around damaged ligament tissue.
The rationale is particularly relevant to the ACL because the ligament sits inside the knee joint. Synovial fluid interferes with formation of the stable fibrin-platelet bridge that would ordinarily develop between the torn ends of an extra-articular ligament. This is one reason the ACL has historically demonstrated less reliable healing than ligaments such as the medial collateral ligament.[20]
PRP may provide a concentrated biological signal and a temporary matrix around the damaged tissue. Whether this is sufficient to improve the frequency, speed or durability of ACL repair remains under investigation.
The current human evidence includes a small retrospective series and individual case reports. These are useful for identifying what may be possible, but they do not have the evidentiary strength of large randomised trials.
PRP Treatment for Acute ACL Injuries
In 2024, Hada and colleagues reported a retrospective series of 10 highly active patients with acute ACL injuries who underwent conservative treatment centred around PRP.[4]
Patients received an average of 2.8 PRP treatments. A simple brace was used to restrict deep flexion, but weight bearing was not restricted in the same way as in the Cross Bracing Protocol.
MRI demonstrated regained ACL continuity in all 10 patients. All returned to their pre-injury activity level at an average of 139.5 days, or approximately 4.6 months. One patient sustained a re-rupture after returning to sport.[4]
The study is small and has no untreated control group. It cannot determine how many ligaments would have regained continuity through natural healing and rehabilitation alone.
Its importance lies in showing that MRI-documented ACL re-continuity may occur within a structured PRP-based pathway without prolonged fixed-angle cross bracing.
Rapid MRI Re-Continuity After Acute PRP Treatment
A 2025 case report from our clinic described a 38-year-old man with a complete ACL rupture and an approximately 13.6 mm gap between the torn ligament ends on baseline 3T MRI.[5]
The patient underwent a series of image-guided treatments using a high-platelet-dose, leukocyte-rich PRP preparation, combined with temporary protection and structured rehabilitation.
Serial 3T MRI demonstrated early fibre bridging by day 10, more robust continuity by day 33 and continued structural maturation by day 52.[5]
The value of this case was the timing and frequency of the MRI examinations. Rather than comparing only an initial scan with an examination months later, the serial imaging showed that morphological change could begin within the first few weeks.
The report cannot establish that the same result will occur in other patients. It does suggest that the early post-injury period may contain an important biological opportunity.
New Publication: Delayed PRP Treatment in a 65-Year-Old Man
Our latest publication extends the ACL healing discussion beyond the young, acute and athletic populations that dominate much of the existing literature.[6]
The patient was 65 years old and underwent MRI one day after injury. The examination demonstrated a complete rupture of the ACL with loss of normal fibre continuity. PRP did not begin immediately. A second MRI was performed 43 days after injury, on the day treatment commenced. It continued to show severe ACL abnormality without a mature, organised ligamentous band. This pretreatment examination is important because structural re-continuity was not clearly established before PRP began.
The patient then received five image-guided autologous PRP treatments between approximately six and 14 weeks after injury. No brace or Cross Bracing Protocol was used.
By 14 weeks after injury, following completion of the PRP series, MRI demonstrated improved fibre organisation and apparent re-continuity along the expected course of the ACL. The patient reported restored movement and a return to normal everyday function at approximately the same time.[6]
A final MRI at 50 weeks demonstrated further maturation of a continuous low-signal ACL-like structure.[6]
The value of this Case to our ongoing World-First Research
Age is relevant to ligament healing. Laboratory evidence suggests that ACL remnant cells and vascular-derived progenitor populations generally demonstrate reduced activity with increasing age. Healing potential may also decline as the injury becomes more chronic.[6,20]
The case therefore sits outside the population in which ACL healing would usually be considered most likely:
- the patient was 65 years old;
- treatment began approximately six weeks after injury;
- the ACL remained severely abnormal on MRI immediately before treatment;
- no bracing protocol was used;
- treatment consisted of five image-guided PRP procedures;
- MRI demonstrated subsequent re-continuity and longer-term maturation.
The case does not establish that age is irrelevant or that delayed treatment is equivalent to early treatment. It suggests that age and a six-week delay may not automatically eliminate the possibility of structural repair.
What the Case Does Not Prove
The limitations are equally important. This was one patient. There was no control group, and spontaneous healing cannot be excluded. The contributions of PRP, natural healing and rehabilitation cannot be separated.
Formal contemporary laxity measurements, validated patient-reported outcome scores and objective return-to-sport testing were not available for publication. MRI continuity does not necessarily mean the ligament has normal tensile strength, proprioception or rotational stability.
Individual platelet counts and total platelet doses were also not available for every treatment session. The PRP was classified according to the preparation protocol, but more complete cellular reporting would strengthen future research.[6,18]
The report should therefore be regarded as hypothesis-generating evidence. It does not justify promising non-surgical repair to every older patient with an ACL rupture.
It does justify asking whether biologically supported ACL healing should be studied beyond the usual acute young-athlete population.
What Is the Sherif ACL Protocol?
The Sherif ACL Protocol is a structured, diagnosis-led pathway for selected patients who wish to explore non-surgical ACL repair before committing to reconstruction.
It is not simply an injection into a painful knee.
The protocol is built around four elements:
1. Detailed 3T MRI Assessment
The first requirement is accurate characterisation of the ACL injury.
The MRI provides a baseline to quantify the efficacy of the treatment and is reviewed for:
- complete or partial rupture;
- tear location;
- separation of the torn ends;
- orientation of the ACL remnants;
- associated meniscal injury;
- cartilage damage;
- bone bruising;
- collateral ligament injury;
- joint effusion;
- features that may influence mechanical stability or healing.
The decision is not based only on the words “complete ACL tear” in a report. Two complete ruptures may have very different morphology and different potential for native-ligament preservation.
2. Image-Guided PRP Delivery
The PRP is delivered under image guidance, targeting the injured ACL region and remnant tissue according to the MRI-defined anatomy.
This differs from placing a routine PRP injection somewhere within the general knee joint and assuming that it will reach the ligament in a meaningful concentration and importantly you have a digital record of exactly where the final needle placement was.
Image guidance allows the treating radiologist to plan the needle pathway and direct the biological preparation towards the relevant ACL tissue.
3. Appropriate Protection and Rehabilitation
Biological treatment cannot overcome repeated mechanical disruption.
The knee must be protected during the early healing phase, but the form and duration of protection may vary according to the tear, the patient and the treatment stage. The Sherif ACL Protocol does not require every patient to remain fixed at 90 degrees for four weeks.
Rehabilitation is then progressed according to symptoms, stability, muscle control and imaging.
The purpose is to create a favourable balance: enough protection to avoid disrupting early repair, while avoiding unnecessary prolonged immobilisation and muscle loss.
4. Serial MRI Confirmation
Repeat MRI is central to the protocol because symptoms alone cannot confirm whether the ACL has reconnected. In acute cases, early interval MRI may be performed approximately two to three weeks after treatment begins to look for bridging, fibre organisation and early continuity. Later imaging evaluates maturation.
The timing is individualised in delayed presentations and more complex injuries.
MRI findings are interpreted alongside:
- clinical stability;
- episodes of giving way;
- range of motion;
- strength;
- rehabilitation progress;
- functional goals;
- orthopaedic assessment where indicated.
A continuous-looking ACL on MRI is encouraging, but it is not permission to return immediately to pivoting sport.
Why PRP Quality Matters in Non-Surgical ACL Treatment
PRP is not one standard product.
Different preparation systems can produce substantially different platelet concentrations, total platelet doses, leukocyte profiles, red blood cell contamination and final volumes. The term “PRP” does not tell the clinician how many platelets were delivered or what other cells were present.[18]
This variation may help explain why PRP studies often produce inconsistent results.
Relevant characteristics include:
- the patient’s baseline platelet count;
- the volume of blood collected;
- platelet recovery efficiency;
- final platelet concentration;
- injected volume;
- total platelet dose;
- neutrophil content;
- monocyte and lymphocyte content;
- red blood cell contamination;
- whether the platelets were activated before injection;
- whether the preparation was delivered directly to the target.
The ideal PRP composition for ACL repair has not been established. Evidence from other musculoskeletal applications suggests that dose and composition can affect biological activity, but results from knee osteoarthritis or tendon treatment cannot simply be transferred to an ACL rupture. Our preference for a ultra high cell count preparation is based on avoiding obvious biological underdosing. It should not be interpreted as proof that the highest possible platelet number guarantees ACL healing.
Future ACL studies need to report the actual product in far greater detail.
A PRP-First ACL Pathway Is Not the Same as Simply Waiting
Some patients understandably worry that attempting non-surgical ACL treatment will delay necessary surgery and allow further damage to occur.
That risk needs to be taken seriously.
A structured non-surgical pathway is different from returning to sport with an unstable knee and waiting to see what happens.
The patient should have:
- an accurate diagnosis;
- appropriate protection;
- activity modification;
- targeted rehabilitation;
- monitoring for instability;
- planned interval imaging;
- access to orthopaedic review;
- clear criteria for progressing to surgery if repair is not occurring.
The interval before ACL reconstruction is often used to allow swelling to settle, restore range of motion and improve quadriceps control. The optimal timing of reconstruction remains patient-specific, and unmanaged delay should not be confused with deliberate prehabilitation or a monitored native-healing trial.[12]
The important principle is that a non-surgical attempt must remain measurable and reversible.
If MRI does not show a favourable repair trajectory, or the knee remains functionally unstable, ACL reconstruction remains available.
Could PRP Still Be Useful If ACL Surgery Is Ultimately Required?
Possibly, although the evidence is not yet definitive.
A 2025 pilot randomised trial studied two leukocyte-poor PRP injections before ACL reconstruction. The investigators found a broader reduction in inflammatory markers within the joint fluid of PRP-treated patients than in aspiration-only controls.[13]
This does not prove that preoperative PRP improves long-term surgical outcomes. It shows that early PRP can alter aspects of the inflammatory environment of the acutely injured knee.
In practical terms, a carefully monitored PRP-first pathway may have two possible outcomes:
- The native ACL demonstrates progressive re-continuity, allowing the patient to continue with a preservation-based pathway.
- Re-continuity does not occur or the knee remains unstable, and the patient proceeds to ACL reconstruction.
The second outcome should not automatically be regarded as a failed or wasted period, particularly if range of motion, muscle control and the intra-articular inflammatory environment have improved before surgery.
That remains a biologically plausible position rather than a proven long-term advantage.
Does PRP Improve Recovery After ACL Reconstruction?
PRP has also been studied as an adjunct during or after ACL surgery.
The results are mixed.
A 2024 randomised clinical trial compared three monthly postoperative intra-articular PRP injections with no PRP after ACL reconstruction. PRP did not produce a superior improvement in overall knee symptoms or function at 12 months. Some differences were observed in sport and recreation scores and graft maturity at six months, but these did not establish a durable overall advantage.[14]
Reviews of PRP augmentation during ACL reconstruction have identified substantial variation in:
- PRP preparation;
- platelet concentration;
- leukocyte content;
- activation;
- liquid or clot form;
- application to the graft, tunnels or joint;
- number and timing of treatments;
- graft choice;
- surgical method;
- imaging assessment;
- length of follow-up.[15]
Recent meta-analyses have reached somewhat different conclusions. Some report modest improvements in early pain, selected functional measures or stability, while others find that any benefits are small, short-lived or below clinically meaningful thresholds.[16,17]
The fairest current conclusion is that PRP after ACL reconstruction remains an adjunct, not a proven replacement for good surgery and rehabilitation. It is also possible that major variation in PRP dose and delivery has obscured whether a more consistent protocol would perform better. That possibility remains unproven.
Native ACL Preservation Is Becoming a Broader Surgical Priority
The move towards ACL preservation is not limited to non-surgical PRP treatment. Bridge-enhanced ACL repair, known as BEAR, is a surgical strategy designed to preserve the torn native ACL rather than replace it with a graft. A scaffold is placed between the torn ligament ends to support healing. In a randomised trial, BEAR produced non-inferior patient-reported outcomes and anteroposterior knee laxity compared with autograft reconstruction at two years. Hamstring strength was better in the BEAR group, although second procedures were numerically more frequent.[7]
Modern primary ACL repair has also re-emerged for selected tear patterns, particularly proximal tears with good tissue quality. Selection remains critical. A systematic review found that skeletally mature patients aged 21 or younger had a substantially higher revision risk after primary ACL repair than after reconstruction. In adults older than 21, the difference was not statistically significant.[8] These findings reinforce a broader direction in ACL care: preservation may be valuable, but not every patient is an appropriate preservation candidate. Age, tear location, tissue quality, instability, sport, timing and patient goals all matter.
Who May Be Considered for Non-Surgical ACL Repair?
There is not yet a universally accepted selection algorithm for PRP-assisted ACL healing.
Potential candidates may include patients who:
- have a recent complete or high-grade ACL tear;
- can begin treatment and protection early;
- have favourable remnant orientation or tear morphology;
- are willing to comply with activity restriction and rehabilitation;
- can undergo serial MRI follow-up;
- do not have repeated uncontrolled giving-way episodes;
- understand that ACL reconstruction may still be required;
- accept that the treatment remains evidence-evolving.
The latest 65-year-old case suggests that older age and treatment beginning at approximately six weeks should not automatically exclude a patient.[6]
It does not establish that all chronic ACL ruptures are treatable. Longer delays may allow retraction, scarring, remnant resorption and biological decline.
Each case requires individual MRI review.
When ACL Surgery May Still Be the Better Treatment
ACL reconstruction should remain a serious early consideration where there is:
- persistent clinical instability;
- recurrent giving way;
- a high-risk return to pivoting or contact sport;
- unfavourable ACL remnant morphology;
- failure to demonstrate reconnection;
- failure of rehabilitation;
- inability to comply with a protected non-surgical pathway;
- patient preference for reconstruction after informed discussion.
Young athletes returning to pivoting sport require particular caution. Both reconstructed and preserved ACLs may fail, but the consequences of recurrent instability can be substantial.[3,8,11]
The role of a regenerative medicine clinic is not to keep every patient away from surgery. It is to identify the patients in whom native-ligament preservation may be reasonable and recognise promptly when surgical treatment is the safer pathway.
How to Choose the Best Regenerative Medicine Clinic in Australia for an ACL Tear
Patients searching for the best regenerative medicine clinic, best PRP clinic or non-surgical ACL repair on the Gold Coast should look beyond general claims about regeneration.
An appropriate ACL program should be able to answer several practical questions.
1- Is the ACL tear properly characterised?
A diagnosis of “ACL rupture” is not enough. The clinic should assess the tear location, gap, remnant orientation, associated meniscal damage and other factors that may influence healing.
2- Can the clinic demonstrate that they have achieved non-surgical ACL repair previously?
A clinic should be able to demonstrate through publications or anonymised imaging that they have achieved successful non-surgical ACL repair with patient return to full function.
3- Is treatment delivered to the ACL under image guidance with patient records for final needle placement?
A generic intra-articular injection is not the same as targeted treatment of the damaged ACL tissue.
4- Does the clinic know what PRP it is using?
The clinician should understand the preparation system, starting blood volume, platelet recovery, cellular composition and approximate biological dose.
5- Is there a structured protection and rehabilitation pathway?
PRP cannot substitute for mechanical protection, muscle recovery and progressive rehabilitation.
6- Is repeat MRI part of the plan?
A clinic claiming to repair a complete ACL should be prepared to demonstrate whether structural reconnection has occurred.
7- Are surgical pathways still respected?
A responsible regenerative medicine clinic should maintain a low threshold for orthopaedic review where the knee remains unstable, MRI is unfavourable or associated injuries require surgery.
8- Are the limitations explained?
Case reports and small series are encouraging but remain early evidence. No clinic should guarantee that PRP will repair every torn ACL.
The best regenerative clinic is not the one that promises the most. It is the one that diagnoses carefully, treats precisely, measures the outcome and changes course when the evidence in that patient is not favourable.
What the Current Evidence Really Means
The ACL can no longer be described as a ligament that is biologically incapable of healing. MRI has documented continuity after rehabilitation, cross bracing and PRP-centred conservative care.[1–6] That does not settle the treatment question. The field now needs to determine which forms of MRI healing produce a mechanically stable, durable ligament and which patients remain at unacceptable risk of giving way, meniscal damage or re-rupture.
The new 65-year-old case expands the boundaries of the discussion. It suggests that structural re-continuity may remain possible after delayed treatment and in an older patient without bracing.[6] It does not prove causation, replace ACL reconstruction or establish a standard treatment protocol. It gives us another reason not to make irreversible assumptions before the individual injury has been properly assessed.
For selected patients, the most appropriate early pathway may be image-guided PRP, temporary protection, structured rehabilitation and repeat MRI. Where reconnection occurs and the knee becomes functionally stable, native ACL preservation may be possible. Where reconnection does not occur, or instability persists, ACL surgery remains available.
That is not an argument against reconstruction. It is an argument for measuring whether the native ligament has a realistic chance to heal before it is replaced.
Author: Dr Kirralee Sherif (PhD)
Frequently Asked Questions About Non-Surgical ACL Repair
Should you have any further questions please visit our FAQs page.
Can a complete ACL tear heal without surgery?
MRI studies have demonstrated regained ACL continuity in some patients managed with rehabilitation, structured bracing or PRP-centred conservative treatment.[1–6] This does not mean every complete ACL rupture will heal or regain adequate mechanical stability.
Can PRP repair a torn ACL?
PRP may support the biological environment for ligament repair, and small clinical series and case reports have documented ACL re-continuity after PRP treatment.[4–6] There are not yet large randomised trials proving that PRP reliably causes complete ACL repair.
Is PRP an alternative to ACL reconstruction?
For selected patients, PRP may provide an opportunity to explore native ACL healing before reconstruction. It is not a universal replacement for ACL surgery. Patients with persistent instability, high-risk sporting goals or significant associated injuries may still be better treated surgically.
How soon should PRP be considered after an ACL tear?
The biological rationale favours early assessment and treatment, before the torn remnants become chronically retracted or scarred. The most recent case report documented re-continuity even though PRP commenced approximately six weeks after injury.[6] The optimal treatment window has not yet been defined.
Can an ACL heal in an older patient?
The new publication documents MRI re-continuity in a 65-year-old man after delayed PRP-based conservative treatment.[6] This is one case and does not establish a general success rate for older patients. It suggests that age alone may not make repair biologically impossible.
Does MRI continuity mean the ACL is completely normal?
No. MRI continuity is an important structural finding, but it does not automatically establish normal tensile strength, rotational control, proprioception or suitability for pivoting sport. Clinical stability and functional testing remain essential.
How long does non-surgical ACL repair take?
Timelines vary. Early bridging has been observed within weeks in an acute published case, while the delayed 65-year-old case demonstrated apparent re-continuity at 14 weeks and continued maturation at 50 weeks.[5,6] Rehabilitation continues beyond the first appearance of continuity.
What happens if the ACL does not reconnect?
ACL reconstruction remains an option. A structured non-surgical pathway should include predetermined review points and should not allow a patient to continue indefinitely with an unstable knee.
Is cross bracing the same as the Sherif ACL Protocol?
No. The Cross Bracing Protocol uses prolonged positioning of the knee at 90 degrees to approximate the torn ligament ends.[2] The Sherif ACL Protocol uses MRI-defined patient selection, image-guided ultra high dose PRP, individualised protection, rehabilitation and serial MRI. It does not routinely require four weeks immobilised at 90 degrees.
Does PRP improve ACL surgery recovery?
PRP may provide modest early benefits in selected studies, but long-term results after ACL reconstruction remain inconsistent.[14–17] It should currently be considered a possible adjunct rather than a routine requirement.
References
1. Filbay SR, Roemer FW, Lohmander LS, Turkiewicz A, Roos EM, Frobell R, Englund M. Evidence of ACL healing on MRI following ACL rupture treated with rehabilitation alone may be associated with better patient-reported outcomes: a secondary analysis from the KANON trial. Br J Sports Med. 2023 Jan;57(2):91-98. doi: 10.1136/bjsports-2022-105473. Epub 2022 Nov 3. PMID: 36328403; PMCID: PMC9872245.
2. , et al Healing of acute anterior cruciate ligament rupture on MRI and outcomes following non-surgical management with the Cross Bracing Protocol
3. Porter MD, Shadbolt B. Cross Bracing Protocol for Anterior Cruciate Ligament (ACL) Rupture Has Unacceptably High Failure Rate Relative to Surgical Stabilization: A 2-year Controlled Cohort Study. Clin J Sport Med. 2026 Jul 1;36(4):444-450. doi: 10.1097/JSM.0000000000001416. Epub 2026 Feb 2. PMID: 41622530.
4. Hada S, Hada M, Yoshida K, Kaneko H, Saita Y, Kubota M, Ishijima M. Conservative Treatment Using Platelet-Rich Plasma for Acute Anterior Cruciate Ligament Injuries in Highly Active Patients: A Retrospective Survey. Cureus. 2024 Jan 28;16(1):e53102. doi: 10.7759/cureus.53102. PMID: 38414705; PMCID: PMC10898500.
5. Sherif Z, Sherif K, Forbes A, Kennedy B, Allen B. Case study of rapid recovery of a complete anterior cruciate ligament rupture through orthobiologic-driven regeneration: magnetic resonance imaging validation. Journal of Orthopaedic Science and Research. 2025;6(3):1–5.
6. Sherif Z, Sherif K, Forbes A. Magnetic resonance imaging-documented re-continuity of a complete anterior cruciate ligament rupture after delayed platelet-rich plasma treatment in a 65-year-old male: a case report. Journal of Orthopaedic Science and Research. 2026;7(2):1–8. doi:10.46889/JOSR.2026.7208.
7. Murray MM, Fleming BC, Badger GJ; BEAR Trial Team; Freiberger C, Henderson R, Barnett S, Kiapour A, Ecklund K, Proffen B, Sant N, Kramer DE, Micheli LJ, Yen YM. Bridge-Enhanced Anterior Cruciate Ligament Repair Is Not Inferior to Autograft Anterior Cruciate Ligament Reconstruction at 2 Years: Results of a Prospective Randomized Clinical Trial. Am J Sports Med. 2020 May;48(6):1305-1315. doi: 10.1177/0363546520913532. Epub 2020 Apr 16. PMID: 32298131; PMCID: PMC7227128.
8. Rilk S, Goodhart GC, van der List JP, Von Rehlingen-Prinz F, Vermeijden HD, O’Brien R, DiFelice GS. Anterior cruciate ligament primary repair revision rates are increased in skeletally mature patients under the age of 21 compared to reconstruction, while adults (>21 years) show no significant difference: A systematic review and meta-analysis. Knee Surg Sports Traumatol Arthrosc. 2025 Jan;33(1):29-58. doi: 10.1002/ksa.12239. Epub 2024 Jul 5. PMID: 38967267; PMCID: PMC11716360.
9. Kunze KN, Moran J, Polce EM, Pareek A, Strickland SM, Williams RJ 3rd. Lower donor site morbidity with hamstring and quadriceps tendon autograft compared with bone-patellar tendon-bone autograft after anterior cruciate ligament reconstruction: a systematic review and network meta-analysis of randomized controlled trials. Knee Surg Sports Traumatol Arthrosc. 2023 Aug;31(8):3339-3352. doi: 10.1007/s00167-023-07402-2. Epub 2023 Mar 31. PMID: 37000243.
10. Peebles LA, Akamefula RA, Aman ZS, Verma A, Scillia AJ, Mulcahey MK, Kraeutler MJ. Following Anterior Cruciate Ligament Reconstruction With Bone-Patellar Tendon-Bone Autograft, the Incidence of Anterior Knee Pain Ranges From 5.4% to 48.4% and the Incidence of Kneeling Pain Ranges From 4.0% to 75.6%: A Systematic Review of Level I Studies. Arthrosc Sports Med Rehabil. 2024 Feb 2;6(2):100902. doi: 10.1016/j.asmr.2024.100902. PMID: 38562662; PMCID: PMC10982565.
11. Wiggins AJ, Grandhi RK, Schneider DK, Stanfield D, Webster KE, Myer GD. Risk of Secondary Injury in Younger Athletes After Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-analysis. Am J Sports Med. 2016 Jul;44(7):1861-76. doi: 10.1177/0363546515621554. Epub 2016 Jan 15. PMID: 26772611; PMCID: PMC5501245.
12. Shen X, Liu T, Xu S, Chen B, Tang X, Xiao J, Qin Y. Optimal Timing of Anterior Cruciate Ligament Reconstruction in Patients With Anterior Cruciate Ligament Tear: A Systematic Review and Meta-analysis. JAMA Netw Open. 2022 Nov 1;5(11):e2242742. doi: 10.1001/jamanetworkopen.2022.42742. PMID: 36394870; PMCID: PMC9672975.
13. Anz AW, Branch EA, Jordan SE, Ostrander RV 3rd, Kindle BJ, Presley JC, Hackel JG, Maggi E, Plummer HA. Preoperative Platelet-Rich Plasma Injections Decrease Inflammatory and Chondrodegenerative Biomarkers in Patients With Acute Anterior Cruciate Ligament Tears: A Pilot Randomized Controlled Trial. Orthop J Sports Med. 2025 Mar 3;13(3):23259671241312754. doi: 10.1177/23259671241312754. PMID: 40052182; PMCID: PMC11881934.
14. Ye Z, Chen H, Qiao Y, Wu C, Cho E, Wu X, Li Z, Wu J, Lu S, Xie G, Dong S, Xu J, Zhao J. Intra-Articular Platelet-Rich Plasma Injection After Anterior Cruciate Ligament Reconstruction: A Randomized Clinical Trial. JAMA Netw Open. 2024 May 1;7(5):e2410134. doi: 10.1001/jamanetworkopen.2024.10134. PMID: 38728032; PMCID: PMC11087838.
15. Delcogliano M, Sangiorgio A, Bensa A, Andriolo L, Boffa A, Filardo G. Platelet-rich plasma augmentation in anterior cruciate ligament reconstruction: Evidence is still too scattered. A scoping review of randomised controlled trials. Knee Surg Sports Traumatol Arthrosc. 2024 May;32(5):1143-1159. doi: 10.1002/ksa.12127. Epub 2024 Mar 15. PMID: 38488226.
16. Serag I, Abouzid M, Hikal H, Abdelhadi A, Abdelaal MN, Mohamed AG, Moawad MHED. Platelet-rich plasma in anterior cruciate ligament reconstruction: An updated systematic review and quantitative meta-analysis of randomized controlled trials. Chin J Traumatol. 2025 Jul 23:S1008-1275(25)00086-0. doi: 10.1016/j.cjtee.2025.02.008. Epub ahead of print. PMID: 40744844.
17. Tayyab M, Ahmad Z, Akbar R, Ahmad M, Shah S, Khan S, Hussain I, Khan AA, Syed R, Khan A, Ali M. Efficacy of Platelet-Rich Plasma Augmentation in Anterior Cruciate Ligament Reconstruction: An Updated Systematic Review and Meta-Analysis of Clinical Trials. Cureus. 2025 Oct 9;17(10):e94181. doi: 10.7759/cureus.94181. PMID: 41210065; PMCID: PMC12595583.
18. Mautner K, Malanga GA, Smith J, Shiple B, Ibrahim V, Sampson S, Bowen JE. A call for a standard classification system for future biologic research: the rationale for new PRP nomenclature. PM R. 2015 Apr;7(4 Suppl):S53-S59. doi: 10.1016/j.pmrj.2015.02.005. PMID: 25864661.
19. Andia, Isabel & Abate, Michele. (2013). Platelet-rich plasma: underlying biology and clinical correlates. Andia I, Abate M. Regen Med. 2013 Sep;8(5):645-58.. Regenerative Medicine. 8. 645-658.
20. Kiapour AM, Murray MM. Basic science of anterior cruciate ligament injury and repair. Bone Joint Res. 2014 Feb 4;3(2):20-31. doi: 10.1302/2046-3758.32.2000241. PMID: 24497504; PMCID: PMC3922117.
