The results of total meniscectomy have led to a more cautious approach to meniscal excision, particularly with surgical techniques removing only the damaged portion of the meniscus.85-88 The thought is that if a portion of the meniscus is preserved, then meniscal function will be more normal as well. Studies have confirmed that removing only the torn portion of a meniscus lowers the severity of postoperative complications, shortens the length of hospital recovery and therapy, and reduces overall pain levels, but the nature of postoperative complications remains the same. These risks include degenerative osteoarthritis, joint instability, femoral and tibial surface damage, and risk of re-injury requiring re-operation.87, 88 Partial meniscectomy, like total meniscectomy, was found via MRI volume measurement to cause cartilage loss at a rate of 4.1% per year; a rate that is 78% faster than controls.89 Other researchers noted when meniscal integrity is compromised, such as with partial meniscectomy, the likelihood of developing degenerative arthritis is large.90, 91 One of the main reasons for this, is that partial meniscectomy by definition puts additional strain on the ligamentous support of the knee to provide stability. Follow-up studies, show that ligament laxity in the medial and lateral collateral ligaments and anterior cruciate ligaments is increased with meniscectomies.92-94 In regard to degenerative symptoms, one study reported that one year after undergoing an operation, 9% of partial meniscectomy patients experienced functional impairment, versus 28% of total meniscectomy patients. Almost seven years later, these numbers had increased to 62% in partial meniscectomy patients and 52% in total meniscectomy patients.95 McGinity et al. documented in his study of post surgical function that “athletes who have undergone partial meniscectomy and total meniscectomy were equally likely to give up sports altogether as a direct result of the operation.”96
As the importance of maintaining complete intact menisci has become more widely recognized, the desire for a less invasive and more curative treatment has been sought out for meniscal injuries. For this reason, many have turned to meniscal repair as their treatment of choice. Meniscal repair utilizes one of several suturing techniques to reattach a torn flap of the meniscus, rather than removing it. In preparation for meniscal repair, the meniscus is generally debrided to remove any tissue that is rendered too loose or “contaminated” to heal, and then the procedure is performed either open or through incision under arthroscopy.97 Meniscal repair is generally reserved for peripheral tears that extend into the red zone, because the likelihood of healing is greater in that region.97, 98
The short-term results of meniscal repair have varied significantly, with a range of both promising and disappointing outcomes.99, 100 As the ability to track long-term results has become possible, repair failures and associated symptoms have been observed in large numbers, proving the effectiveness of this treatment to be questionable at best. Preoperative symptoms have been shown to resurface as early as six months following meniscal repair, and can lead to long-term joint damage prevalent decades later.101, 102 Specifically, as documented by CT arthrogram, completely healing from meniscal repair was found in only 58% of the menisci.101 After a 13 year follow-up the failure rate in one Swedish study was 29%.102 In this same study, knee function showed a statistically significant decline in the meniscal-repaired knee compared to the non-operated knee. The authors noted, “We conclude that 13 years after repair, knee function is good but not better than after meniscectomy and not as good as in an uninjured knee.”
A failed meniscal repair is generally defined as lack of improvement after operation or, more specifically, any re-injury and subsequent re-operation. Re-injury after meniscal repair is not uncommon, affecting the original site of injury as well as new areas of the meniscus. Six independently performed studies, conducted an average of eight years after a repair, found that 10% to 38% of all meniscal repairs were considered failures.103-108 The 38% failure rate was in patients under the age of 18. It is also worth noting that these injuries were not isolated, but in many cases occurred in addition to the return of multiple preoperative symptoms, such as joint pain, instability, weakness, and swelling. In summary, it can be concluded that about 25% of all meniscal repairs are failures. In more practical terms, for 25% of all patients undergoing meniscal repair, the surgery will either not relieve their symptoms or the repair will fail and their symptoms will again return and need another operation or some other form of therapy. For instance, in one study, meniscectomy was needed in 10% of the patients after meniscal repair.109 Considering the average follow-up for these groups of studies was eight years, imagine what the failure rate of meniscal repairs would be at 16 or 24 years!
Another concern associated with meniscal repair is, not surprisingly, long-term degenerative osteoarthritis.109-112 This makes sense since a great percentage of meniscal repairs do not heal completely. One study found that only 30% of patients after meniscal repair showed no signs of osteoarthritis, whereas 83% of patients exhibited no signs of osteoarthritis before the treatment.109 Although meniscal repair is most frequently performed in regions of greater vascularity, the treatment does not actually stimulate meniscal healing through vascular supply.110 There was a 12% re-injury rate after meniscal repair in this study.
The most recent contribution to surgical treatment of meniscus injuries has been the advent of the meniscal transplant. Transplantation can be performed either with human allograft or artificial collagen implants, with the majority utilizing deep-frozen cryopreserved allografts extracted from human cadaver knees. Before a transplant can be conducted, the patient must undergo arthroscopic removal of any remaining meniscal tissue to prepare for the new implant. Using one of two techniques, a bone plug or a bridge, the implant is then placed inside the knee in alignment with the femur and tibia, and then sutured into place. This procedure requires careful measurement of the meniscus and precision in matching the size and placement of a new meniscus, as even the slightest error in measurement could cause improper tracking and damage to the knee.113
This method has been monitored closely for short-term results, but because it is a relatively new treatment and methods between studies have varied, long-term results are difficult to assess. Based on what information we do have, however, hope for long-term relief remains questionable. In a number of studies spanning from two to seven years after allograft transplantation, failure rates ranged from 28% to 58%, where symptoms such as allograft deterioration, new tears, and unresolved pain symptoms resulted in premature removal of allografts or additional arthroscopic surgeries.113-115 As one study states, “[patients] should be advised that the procedure is not curative in the long term, and additional surgery will most likely be required.”113 (See Figure 12.) Recovery time is another important issue in assessing any treatment, and transplants have a longer rehabilitation time than other meniscal operations. In documented transplantation cases, patients did not begin physical rehabilitation until eight weeks post operation, at which time they were started on non-strenuous activities such as cycling, followed by swimming and walking, between nine and 12 weeks post operation. Even in the most successful knees, patients were informed that they should never return to arduous physical activity, including athletics.114 Meniscal transplantation with such a high failure rate, diminishes the hope that anyone, especially athletes, would have for maintaining an active lifestyle.
Although there is some short term improvement in aspects such as pain control, the long term effects of meniscectomy, meniscal repair, and meniscal allograft transplantation reveal that symptoms, such as pain and instability, will persist for years afterward. The main reason that these and other treatments are ineffective in healing the meniscus can simply be attributed to the fact that, regardless of what is done to structurally repair the meniscus, it is still primarily an avascular cartilaginous structure which cannot heal without a sufficient supply of nutrition. The poor healing potential of meniscal tears has led to the investigation of methods to provide blood supply to the injured area. The methods include vascular access channels and synovial pedicale flaps. Unfortunately, no surgical treatment to date has been shown to stimulate healing of the meniscus. On the contrary, surgeries often have the opposite effect. They initiate additional damage to the joint, further decreasing the probability of healing. Current surgical techniques for meniscal injuries accelerate menisci and joint degeneration. Perhaps Lohmander et al. in their comprehensive review of surgical procedures for meniscal pathology said it best, “there is a lack of evidence to support a protective role of repair or reconstructive surgery of the anterior cruciate ligament or meniscus against osteoarthritis development…Osteoarthritis developed in the injured joints is caused by intraarticular pathogenic processes initiated at the time of injury, combined with long-term changes in dynamic joint loading.”116 The bottom line is surgical procedures do not initiate the regenerative process needed in these traumatized knee joints. Left alone or treated by the surgery, the degenerative process initiated by the initial trauma continues, unless something is done to initiate regeneration. The reverse of degeneration is simply regeneration. In other words, a degenerative process can only be reversed when stimulated to repair itself. Degeneration of the meniscus is initiated by a damaged meniscus’ inability to repair itself, and the surgical procedures themselves accelerate the degenerative process. The ideal treatment for the damaged meniscus is one that can stimulate regeneration of the degenerated or torn meniscus. The injection technique whereby the proliferation of cells is stimulated via growth factor production is called Prolotherapy. (See Figure 13.)
| Figure 12. Arthroscopy of the knee. Arthroscopy of the knee for meniscal injury is often non-curative and can lead to long term problems, including degenerative arthritis. |
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| Figure 13. Effects of treatments for meniscal tears. Only Prolotherapy stimulates the repair of injured meniscal tissue. |
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